The water companies have large storage a_The filtration of public water-supplies Third edition, revised and enlarged.

an aggregate capacity equal to nine days’ supply, but the proportion

varies widely with the different companies. It is desired that the

water held in reserve shall be alone used while the river is in flood,

as, owing to its increased pollution, it is regarded as far more

dangerous than the water at other times; but as no record is kept of

the times when raw sewage is discharged, and no exact information is

available in regard to the times when the companies do not take in

raw water, it can safely be assumed that a considerable amount of raw

sewage does become mixed with the water which is drawn by the companies.

The water drawn from the river is filtered through 113 filters having

an area of 116 acres. None of the filters are covered, and with an

average January temperature of 39° but little trouble with ice is

experienced. A few new filters are provided with appliances for

regulating the rate on each filter separately and securing regular and

determined rates of filtration, but nearly all of the filters are of

the simple type described on page 48, and the rates of filtration are

subject to more or less violent fluctuation, the extent of which cannot

be determined.

The area of filters is being continually increased to meet increasing

consumption; the approximate areas of filters in use having been as

follows:

1839 First filters built

1855 37 acres

1866 47 acres

1876 77 acres

1886 104 acres

1894 116 acres

There has been a tendency to reduce somewhat the rate of filtration. In

1868, with 51 acres of filters, the average daily quantity of water

filtered was 111,000,000 gallons, or 2,180,000 gallons per acre. In

1884, with 97 acres of filter surface, the daily quantity filtered was

157,000,000 gallons, or 1,620,000 gallons per acre; and in 1893, with

116 acres of filter surface and 195,000,000 gallons daily, the yield

per acre was 1,680,000 gallons.

Owing to the area of filter surface out of use while being cleaned,

the variations in consumption of water, and the imperfections of the

regulating apparatus, the actual rates of filtration are often very

much higher and at times may easily be double the figures given.

Evidence regarding the healthfulness of the filtered river-water was

collected and examined in a most exhaustive manner in 1893 by a Royal

Commission appointed to consider the water-supply of the metropolis in

all its aspects with reference to future needs. This commission was

unable to obtain any evidence whatever that the water as then supplied

was unhealthy or likely to become so, and they report that the rivers

can safely be depended upon for many years to come.

The numbers of deaths from all causes and from typhoid fever annually

per million of inhabitants for the years 1885-1891 in the populations

receiving their waters from different sources in London were as follows:

Water used. Deaths from Deaths from

All Causes. Typhoid Fever.

Filtered Thames water only 19,501 125

Filtered Lea water only 21,334 167

Kent wells only 18,001 123

Thames and Lea jointly 18,945 138

Thames and Kent jointly 18,577 133

The population supplied exclusively from the Lea by the East London

Company is of a poorer class than that of the rest of London, and this

may account for the slightly higher death-rate in this section. Aside

from this the rate is remarkably uniform and shows no great difference

between the section drinking ground-water only and those drinking

filtered river-waters. The death-rate from typhoid fever is also very

uniform and, although higher than that of some Continental cities with

excellent water-supplies (Berlin, Vienna, Munich, Dresden), is very

low—lower than in any American city of which I have records.

In this connection, it was shown by the Registrar-General that there

is only a very small amount of typhoid fever on the watersheds of

the Thames and Lea, so that the danger of infection of the water as

distinct from pollution is less than would otherwise be the case. Thus

for the seven years above mentioned the numbers of deaths from typhoid

fever per million of population were only 105 and 120 on the watersheds

of the Thames and the Lea respectively, as against 176 for the whole of

England and Wales.

LONDON FILTERS, 1896.

Twenty-sixth Annual Report of the Local Government Board, pages 206-213.

--------------+-------+---------+-----------------+--------------------------

|Amount |Average | Average Rate | Bacterial Efficiency.

| of |Thickness| of Filtration. |

|Storage| of +--------+--------+--------+--------+--------

--------------+-------+---------+--------+--------+--------+--------+--------

Chelsea | 12.0 | 4.0 | 1.75 | 2.19 | 99.92 | 99.62 | 99.86

West Middlesex| 5.6 | 2.75 | 1.25 | 1.56 | 99.94 | 91.48 | 99.79

Vauxhall | 4.1 | 2.5 | 1.5 | 1.88 | 100.00 | 84.33 | 97.77

Grand Junction| 3.3 | 2.25 | 1.63 | 2.05 | 99.98 | 84.03 | 99.31

Lambeth | 6.0 | 2.8 | 2.08 | 2.60 | 99.97 | 96.45 | 99.81

New River | 2.2 | 4.4 | 1.89 | 2.37 | 100.00 | 77.14 | 99.07

East London | 15.0 | 2.0 | 1.33 | 1.67 | 99.93 | 97.03 | 99.56

--------------+-------+---------+--------+--------+--------+--------+--------

APPENDIX VI.

THE BERLIN WATER-WORKS.

The original works were built by an English company in 1856, and were

sold to the city in 1873 for $7,200,000.

The water was taken from the river Spree at the Stralau Gate, which

was then above, but is now surrounded by, the growing city. The water

was always filtered, and the original filters remained in use until

1893, when they were supplanted by the new works at Lake Müggel. Soon

after acquiring the works the city introduced water from wells by Lake

Tegel as a supplementary supply, but much trouble was experienced from

crenothrix, an organism growing in ground-waters containing iron, and

in 1883 this supply was replaced by filtered water from Lake Tegel.

With rapidly-increasing pollution of the Spree at Stralau the purity

of this source was questioned, and in 1893 it was abandoned (although

still held as a reserve in case of urgent necessity), the supply now

being taken from the river ten miles higher up, at Müggel.

The watershed of the Spree above Stralau, as I found by map

measurement, is about 3800 square miles; the average rainfall is about

25 inches yearly. At extreme low water the river discharges 457 cubic

feet per second, or 295 million gallons daily, and when in flood 5700

cubic feet per second may be discharged. The city is allowed by law to

take 46 million gallons daily for water-supply, and this quantity can

be drawn either at Stralau or at Müggel.

Above Stralau the river is polluted by numerous manufactories and

washing establishments, and by the effluent from a considerable part

of the city’s extensive sewage farms. The shipping on this part of the

river also is heavy, and sewage from the boats is discharged directly

into the river. The average number of bacteria in the Spree at this

point is something over ten thousand per cubic centimeter, and 99.6 per

cent of them were removed by the filters in 1893.

The watershed of the Spree above the new water-works at Müggel I found

by map measurement to be 2800 square miles, and the low water-discharge

is said to be 269 million gallons daily. The river at this point flows

through Lake Müggel, which forms a natural sedimentation-basin, and the

raw water is quite clear except in windy weather.

There were 16 towns on the watershed with populations above 2000 each

in 1890, and an aggregate population of 132,000, which does not include

the population of the smaller places or country districts. None of

these places purify their sewage so far as they have any. Fürstenwalde

with a population of 12,935, and 22 miles above Müggel, has surface

sewers discharging directly into the river. Above Fürstenwalde the

river runs through numerous lakes which probably remove the effect

of the pollution from the more distant cities. There is considerable

shipping on the river for some miles above Fürstenwalde (which forms a

section of the Friedrich Wilhelm Canal), but hardly any between Müggel

and Fürstenwalde. The raw water at Müggel contains two or three hundred

bacteria per cubic centimeter, and is thus a comparatively pure water

before filtration. It is slightly peaty and the filtered water has a

light straw color.

Lake Tegel, which supplies the other part of the city’s supply, is an

enlargement of the river Havel. The watershed above Tegel I find to be

about 1350 square miles, and the annual rainfall is about 22 inches.

The low water-discharge is said to be 182 million gallons daily, and

the city is allowed by law to take 23 million gallons for water-supply.

There were ten towns upon the watershed with populations above 2000

each in 1890, and with an aggregate population of 44,000. Of these

Tegel is directly upon the lake with a population of 3000, and

Oranienburg, 14 miles above, has a population of 6000 and is rapidly

increasing. The shipping on the lake and river is heavy. The lake water

ordinarily contains two or three hundred bacteria per cubic centimeter.

The lake is shallow and becomes turbid in windy weather.

There are 21 filter-beds at Tegel with a combined area of 12.40 acres

to furnish a maximum of 23 million gallons of water daily, and 22

filters at Müggel with a combined area of 12.7 acres to deliver the

same quantity. Twenty-two more filters will be built at Müggel within

a few years to purify the full quantity which can be taken from the

river. All of these filters are covered with brick arches supported by

pillars about 16 feet apart from centre to centre in each direction,

and the whole is covered by nearly 3 feet of earth, making them quite

frost-proof. The original filters at Stralau were open, but much

difficulty was experienced with them in winter.

The bottom of the filters at Tegel consists of 8 inches of concrete

above 20 inches of packed clay and with 2 inches of cement above, and

slopes slightly from each side to the centre. The central drain goes

the whole length of the filters and has a uniform cross-section of

about 1/7300 of the area of the whole bed. There are no lateral drains,

but the water is brought to the central drain by a twelve-inch layer

of stones as large as a man’s fist; above this there is another foot

of gravel of graded sizes supporting two feet of fine sand, which is

reduced by scraping to half its thickness before the sand is replaced.

The average depth of water above the sand is nearly 5 feet. The filters

are not allowed to filter at a rate above 2.57 million gallons per

acre daily, and at this rate with 70 per cent of the area in service

the whole legal quantity of water can be filtered. The filters work

at precisely the same rate day and night, and the filtered water

is continuously pumped as filtered to ample storage reservoirs at

Charlottenburg. The pumps which lift the water from the lake to the

filters work against a head of 14 feet. The apparatus for regulating

the rate of filtration was described on page 51.

As yet no full description of the Müggel works has been published, but

they resemble closely the Tegel works. Both were designed by or under

the direction of the late director of the water-works, Mr. Henry Gill.

The average daily quantity of water supplied for the fiscal year ending

March 31, 1893, was 29,000,000 gallons daily, which estimate allows

10 percent for the slip of the pumps. Of this quantity 9,650,000 was

furnished by Stralau and 19,350,000 by Tegel. The greatest consumption

in a single day was 43,300,000 gallons, or 26.6 gallons per head,

while the average quantity for the year was 18.4 gallons per head. All

water without exception is sold by meter, the prices ranging from 27.2

cents a thousand gallons for small consumers to 13.6 cents for large

consumers and manufacturers. The average receipts for all water pumped,

including that used for public purposes and not paid for, were 15.4

cents a thousand gallons, against the cost of production, 9.8 cents,

which covers operating expenses, interest on capital, and provision for

sinking fund. This leaves a handsome net profit to the city. On account

of the comparatively high price of the city water and the ease with

which well-water is obtained, the latter is almost exclusively used

for running engines, manufacturing purposes, etc., and this in part

explains the very low per-capita consumption.

The volume of sewage, however, for the same year, including rain-water,

except during heavy showers, was only 29 gallons per head, showing even

with the private water-supplies an extraordinarily low consumption.

The friction of the water in the 4.75 miles of 3-foot pipe between

Tegel and the reservoir at Charlottenburg presents an interesting

point. When well-water with crenothrix was pumped, the friction rose

to 34.5 feet, when the velocity was 2.46 feet per second. According to

Herr Anklamm, who had charge of the works at the time, the friction was

reduced to 19.7 feet when filtered water was used and after the pipe

had been flushed, and this has not increased with continued use. He

calculated the friction for the velocity according to Darcy 15.0 feet,

Lampe 17.8 feet, Weisbach 18.7 feet, and Prony 21.5 feet.

APPENDIX VII.

ALTONA WATER-WORKS.

The Altona water-works are specially interesting as an example of

a water drawn from a source polluted to a most unusual extent: the

sewage from cities with a population of 770,000, including its own, is

discharged into the river Elbe within ten miles above the intake and

upon the same side.

The area of the watershed of the Elbe above Altona is about 52,000

square miles, and the average rainfall is estimated to be about

28 inches, varying from 24 or less near its mouth to much higher

quantities in the mountains far to the south. On this watershed there

are 46 cities, which in 1890 had populations of over 20,000 each,

and in addition there is a permanent population upon the river-boats

estimated at 20,000, making in all 5,894,000 inhabitants, without

including either country districts or the numberless cities with less

than 20,000 inhabitants each. The sewage from about 1,700,000 of these

people is purified before being discharged; and assuming that as many

people living in cities smaller than 20,000 are connected with sewers

as live in larger places without being so connected, the sewage of

over four million people is discharged untreated into the Elbe and its

tributaries.

The more important of these sources of pollution are the following:

City Population On what Approximate

in 1890. River. Distance, Miles.

Shipping 20,000

Altona 143,353 Elbe 6

Hamburg 570,534 Elbe 7

Wandsbeck 20,586 Elbe 8

Harburg 35,101 Elbe 11

Magdeburg 202,325 Elbe 185

Dresden 276,085 Elbe 354

Berlin and suburbs 1,787,859 Havel 243

Halle 101,401 Saale 272

Leipzig 355,485 Elster 305

Chemnitz 138,955 Mulde 340

Prague 310,483 Moldau 500

The sewage of Berlin and of most of its suburbs is treated before being

discharged, and in addition the Havel flows through a series of lakes

below the city, allowing better opportunities for natural purification

than in the case of any of the other cities. Halle treats less than a

tenth of its sewage. Magdeburg will treat its sewage in the course of

a few years. Leipzig, Chemnitz, and other places are thinking more or

less seriously of purification.

The number of bacteria in the raw water at Altona fluctuates with the

tide and is extremely variable; numbers of 50,000 and 100,000 are not

infrequent, but 10,000 to 40,000 is perhaps about the usual range.

The works were originally built by an English company in 1860, and have

since been greatly extended. They were bought by the city some years

ago. The water is pumped directly from the river to a settling-basin

upon a hill 280 feet above the river. From this it flows by gravity

through the filters to the slightly lower pure-water reservoir and

to the city without further pumping. The filters are open, with

nearly vertical masonry walls, as described in Kirkwood’s report. The

cross-section of the main underdrain is 1/2800 of the area of the beds.

Considerable trouble has been experienced from frost. With continued

cold weather it is extremely difficult to satisfactorily scrape the

filters, and very irregular rates of filtration may result at such

times. In the last few years, with systematic bacterial investigation,

it has been found that greatly decreased efficiency frequently follows

continued cold weather, and the mild epidemics of typhoid fever

from which the city has long suffered have generally occurred after

these times. Thus a light epidemic of typhoid in 1886 came in March,

following a light epidemic in Hamburg. In 1887 a severe epidemic in

February followed a severe epidemic in Hamburg in December and January.

In 1888 a severe epidemic in March followed an epidemic in Hamburg

lasting from November to January. Hamburg’s epidemic of 1889, coming in

warm weather, September and October, was followed by only a very slight

increase in Altona. In 1891 Altona suffered again in February from a

severe epidemic, although very little typhoid had been in Hamburg. A

less severe outbreak also came in February, 1892, and a still slighter

one in February, 1893. In the ten years 1882-1892, of five well-marked

epidemics, three broke out in February and two in March, while two

smaller outbreaks came in December and January. No important outbreak

has ever occurred in summer or in the fall months, when typhoid

is usually most prevalent, thus showing clearly the bad effect of

frost upon open filters (see Appendix II). With steadily increasing

consumption the sedimentation-basin capacity of late years has become

insufficient as well as the filtering area, and it is not unlikely that

with better conditions a much better result could be obtained in winter

even with open filters.[63]

The brilliant achievement of the Altona filters was in the summer of

1892, when they protected the city from the cholera which

so ravaged Hamburg, although the raw water at Altona must have

contained a vastly greater quantity of infectious matter than that

which worked such havoc in Hamburg.

From these records it appears that for about nine months of the year

the Altona filters protect the city from the impurities of the Elbe

water, but that during cold weather, with continued mean temperatures

below the freezing-point, such protection is not completely afforded,

and bad effects have occasionally resulted. Notwithstanding the recent

construction of open filters in Hamburg it appears to me that there

must always be more or less danger from open filters in such a climate.

Hamburg’s danger, however, will be much less than Altona’s on account

of its better intake above the outlets of the sewers of Hamburg and

Altona, which are the most important points of pollution at Altona.

APPENDIX VIII.

HAMBURG WATER-WORKS.

The source and quality of the water previously supplied has been

sufficiently indicated in Appendix II. It was originally intended to

filter the water, but the construction of filters was postponed from

time to time until the fall of 1890, when the project was seriously

taken up, and work was commenced in the spring of 1891. Three years

were allowed for construction. In 1892, however, the epidemic of

cholera came, killing 8605 residents and doing incalculable damage to

the business interests of the city. The health authorities found that

the principal cause of this epidemic was the polluted water-supply.

To prevent a possible recurrence of cholera in 1893, the work of

construction of the filters was pressed forward much more rapidly than

had been intended. Electric lights were provided to allow the work to

proceed nights as well as days, and as a result the plant was put in

operation May 27, 1893, a full year before the intended time. Owing to

the forced construction the cost was materially increased.

The new works take the raw water from a point one and a half miles

farther up-stream, where it is believed the tide can never carry the

city’s own sewage, as it did frequently to the old intake. The water

is pumped from the river to settling-basins against heads varying with

tide and the water-level in the basins from 8 to 22 feet. Each of the

four settling-basins has an area of about 10 acres, and, with the water

6.56 feet deep, holds 20,500,000 gallons, or 82,000,000 gallons in

all. The works are intended to supply a maximum of 48,000,000 gallons

daily, but the present average consumption is only about 35,000,000

gallons (1892), or 59 gallons per head for 600,000 population.

This consumption is regarded as excessive, and it is hoped that it

will be reduced materially by the more general use of meters. The

sedimentation-basins are surrounded by earthen embankments with slopes

of 1:3, the inner sides being paved with brick above a clay layer. The

water flows by gravity from these basins to the filters, a distance

of 1-1/2 miles, through a conduit 8-1/2 feet in diameter. The flow of

the water out of the basins and from the lower end of the conduit is

regulated by automatic gates connected with floats, shown by Fig. 11,

page 60.

The filters are 18 in number, and each has an effective area of 1.89,

or 34 acres in all. They are planned to filter at a rate of 1.60

million gallons per acre daily, which with 16 filters in use gives a

daily quantity of 48,000,000 gallons as the present limit of the works.

The sides of the filters are embankments with 1:2 slopes. Both sides

and bottoms have 20 inches of packed clay, above which are 4 inches of

puddle, supporting a brick pavement laid in cement. The bricks are laid

flat on the bottom, but edge-wise on the sides where they will come in

contact with ice.

The main effluent-drain has a cross-section for the whole length of

the filter of 4.73 square feet, or 1/17000 of the area of the filter;

and even at the low rate of filtration proposed, the velocity in the

drain will reach 0.97 foot. The drain has brick sides, 1.80 feet

high, covered with granite slabs. The lateral drains are all of brick

with numerous large openings for admission of water. They are not

ventilated, and I am unable to learn that any bad results follow this

omission.

The filling of the filters consists of 2 feet of gravel, the top being

of course finer than the bottom layers, above which are 40 inches of

sand, which are to be reduced to 24 inches by scraping before being

refilled. The water over the sand, when the latter is of full depth,

is 43 inches deep, and will be increased to 59 inches with the minimum

sand-thickness. The apparatus for regulating the rate of filtration was

described page 52. The cost of the entire plant, including 34 acres

effective filter-surface, 40 acres of sedimentation-basins, over 2

miles of 8-1/2-foot conduit, pumping-machinery, sand-washing apparatus,

laboratory, etc., was about 9,500,000 marks, or $2,280,000. This all

reckoned on the effective filter area is $67,000 per acre, or $3.80 per

head for a population of 600,000.

The death-rate since the introduction of filtered water has been lower

than ever before in the history of the city, but as it is thought that

other conditions may help to this result, no conclusions are as yet

drawn.

DEATHS IN HAMBURG FROM ALL CAUSES, AND FROM TYPHOID FEVER, BEFORE AND

AFTER THE INTRODUCTION OF FILTERS.

--------------------+-----------+-----------+--------------

|Deaths from|Deaths from|

|all Causes | Typhoid |

Year. | per 1000 | Fever per |

| Living. | 100,000 |

| | Living. |

--------------------+-----------+-----------+--------------

1880 | 24.9 | 26 |

1881 | 24.1 | 30 |

1882 | 23.7 | 27 |

1883 | 25.2 | 25 |

1884 | 25.1 | 26 |

1885 | 25.3 | 42 |

1886 | 29.0 | 71 |

1887 | 26.6 | 88 |

1888 | 24.5 | 54 |

1889 | 23.5 | 43 |

1890 | 22.0 | 27 |

1891 | 23.4 | 24 |

1892 | 41.1 | 34 |Cholera year.

1893 | 20.2 | 18 |Filtered water

| | | from May 28.

1894 | 17.9 | 7 |

1895 | 19.0 | 11 |

1896 | 17.3 | 6 |

1897 | 17.0 | 7 |

1898 | 17.5 | 5 |

Average for 5 years,| | |

excluding cholera | | |

year, before | | |

filtration, | | |

1887 to 1891 | 24.0 | 47.2 |

Average for 5 years | | |

with filtration, | | |

1894 to 1898 | 17.7 | 7.2 |

--------------------+-----------+-----------+--------------

APPENDIX IX.

NOTES ON SOME OTHER EUROPEAN WATER-SUPPLIES.

=Amsterdam.=—The water is derived from open canals in the dunes. These

canals have an aggregate length of about 15 miles, and drain about 6200

acres. The water, as it enters the canals from the fine dune-sand,

contains iron, but this is oxidized and deposited in the canals. The

water after collection is filtered. It has been suggested that by using

covered drains instead of open canals for collecting the water, the

filtration would be unnecessary; but, on the other hand, the cost of

building and maintaining covered drains in the very fine sand would be

much greater than that of the canals, and it is believed, also, that

the water so collected would contain iron, the removal of which might

prove as expensive as the present filtration. In 1887 filters were

built to take water from the river Vecht, but the city has refused to

allow the English company which owns the water-works to sell this water

for domestic purposes, and it is only used for public and manufacturing

purposes, only a fraction of the available supply being required.

Leyden, the Hague, and some other Dutch cities have supplies like the

dune supply of Amsterdam, and they are invariably filtered.

=Antwerp= is also supplied by an English company. The raw water is

drawn from a small tidal river, which at times is polluted by the

sewage of Brussels. It is treated by metallic iron in Anderson revolver

purifiers, and is afterward filtered at a rather low average rate. The

hygienic results are closely watched by the city authorities, and are

said to be satisfactory.

=Rotterdam.=—The raw water is drawn from the Maas, as the Dutch

call the main stream of the Rhine after it crosses their border. The

population upon the river and its tributaries in Switzerland, Germany,

Holland, France, and Belgium is very great; but the flow is also great,

and the low water flow is exceptionally large in proportion to the

average flow, on account of the melting snow in summer in Switzerland,

where it has its origin.

The original filters had wooden under-drains, and there was constant

trouble with crenothrix until the filters were reconstructed without

wood, since which time there has been no farther trouble. The present

filters are large and well managed. There is ample preliminary

sedimentation.

=Schiedam.=—The filters at Schiedam are comparatively small, but are

of unusual interest on account of the way in which they are operated.

The intake is from the Maas just below Rotterdam. The city was unable

to raise the money to seek a more distant source of supply, and the

engineer, H. P. N. Halbertsma, was unwilling to recommend a supply

from so doubtful a source without more thorough treatment than simple

sand-filtration was then thought to be. The plan adopted is to filter

the supply after preliminary sedimentation through two filters of 0.265

acre each, and the resulting effluent is then passed through three

other filters of the same size. River sand is used for the first, and

the very fine dune sand for the second filtration. The cost both of

construction and operation was satisfactory to the city, and much below

that of any other available source; and the hygienic results have been

equally satisfactory, notwithstanding the unfavorable position of the

intake.

=Magdeburg.=—The supply is drawn from the Elbe, and is filtered through

vaulted filters after preliminary sedimentation. The pollution of

the river is considerable, although less than at Altona or even at

Hamburg. The city has been troubled at times by enormous discharges of

salt solution from salt-works farther up, which at extreme low water

have sometimes rendered the whole river brackish and unpleasant to the

taste; but arrangements have now been made which, it is hoped, will

prevent the recurrence of this trouble.

=Breslau= is supplied with filtered water from the river Oder,

which has a watershed of 8200 square miles above the intake, and is

polluted by the sewage from cities with an aggregate population of

about 200,000, some of which are in Galicia, where cholera is often

prevalent. In recent years the city has been free from cholera, and

from more than a very limited number of typhoid-fever cases; but the

pollution is so great as to cause some anxiety, notwithstanding the

favorable record of the filters, and there is talk of the desirability

of securing another supply. Until 1893 there were four filter-beds,

with areas of 1.03 acres each, and not covered. In 1893 a fifth bed was

added. This is covered by vaulting and is divided into four sections,

which are separately operated, so that it is really four beds of 0.25

acre each. The vaulting is concrete arches, supported by steel I beams

in one direction.

=Budapest.=—A great variety of temporary water-supplies have at

different times been used by this rapidly growing city. The filters

which for some years have supplied a portion of the supply have not

been altogether satisfactory; but perhaps this was due to lack of

preliminary sedimentation for the extremely turbid Danube water, and

also to inadequate filter-area. The city is rapidly building and

extending works for a supply of ground-water, and in 1894 the filters

were only used as was necessary to supplement this supply, and it was

hoped that enough well-water would be obtained to allow the filters to

be abandoned in the near future. The Danube above the intake receives

the sewage of Vienna and innumerable smaller cities, but the volume of

the river is very great compared to other European streams, so that the

relative pollution is not so great as in many other places.

=Zürich.=—The raw water is drawn by the city from the Lake of Zürich

near its outlet, and but a few hundred feet from the heart of the city.

Although no public sewers discharge into the lake, there is some

pollution from boats and bathers and other sources, and, judging by

the number of bacteria in the raw water, this pollution is increasing.

The raw water is extremely free from sediment, and the filters only

become clogged very slowly. The rate of filtration is high, habitually

reaching 7,000,000 gallons per acre daily; but, with the clear lake

water and long periods between scrapings, the results are excellent

even at this rate. The filters are all covered with concrete groined

arches.

Filtration was commenced in 1886, and was followed by a sharp decline

in the amount of typhoid fever, which, up to that time, had been rather

increasing; for the six years before the change there were sixty-nine

deaths from this cause annually per 100,000 living, and for the six

years after only ten, or one seventh as many; and this reduction is

attributed by the local authorities to the filtration.[64]

=St. Petersburg.=—The supply is drawn from the Neva River by an English

company, and is filtered through vaulted filters at a very high rate.

=Warsaw.=—The supply is drawn from the Weichsel River by the city, and

is filtered through vaulted filters after preliminary sedimentation at

a rate never exceeding 2,570,000 gallons per acre daily.

THE USE OF UNFILTERED SURFACE-WATERS.

The use of surface-water without filtration in Europe is comparatively

limited. In Germany this use is now prohibited by the Imperial Board

of Health. In Great Britain, Glasgow draws its supply unfiltered from

Loch Katrine; and Manchester and some other towns use unfiltered

waters from lakes or impounding reservoirs the watersheds of which are

entirely free from population. The best English practice, however, as

in Germany, requires the filtration of such waters even if they are not

known to receive sewage, and the

unpolluted supplies of Liverpool, Bradford, Dublin, and many other

cities are filtered before use.

THE USE OF GROUND-WATER.[65]

Ground-waters are extensively used in Europe, and apparently in

some localities the geological formations are unusually favorable

to this kind of supply. Paris derives all the water it now uses for

domestic purposes from springs, but has a supplementary supply from

the river for other purposes. Vienna and Munich also obtain their

entire supplies from springs, while Budapest, Cologne, Leipzig,

Dresden, Frankfurt, many of the great French cities, Brussels, a part

of London, and many other English cities derive their supplies from

wells or filter-galleries, and among the smaller cities all over Europe

ground-water supplies are more numerous than other kinds.

APPENDIX X.

LITERATURE OF FILTRATION.

The following is a list of a number of articles on filtration. The

list is not complete, but it is believed that it contains the greater

part of articles upon slow sand-filtration, and that it will prove

serviceable to those who wish to study the subject more in detail.

ANKLAMM. Glasers Annalen, 1886, p. 48.

A description of the Tegel filters at Berlin, with excellent plans.

BAKER. Engineering News.

Water purification in America: a series of descriptions of filters, as

follows: Aug. 3, 1893, Lawrence filter and description of apparatus of

screening sand and gravel; Apr. 26, 1894, filter at Nantucket, Mass.;

June 7, 1894, filters at Ilion, N. Y., plans; June 14, 1894, filters

at Hudson, N. Y.; July 12, 1894, filters at Zürich, Switzerland,

plans; Aug. 23, 1894, filters at Mt. Vernon, N. Y., plans.

BERTSCHINGER. Journal für Gas- und Wasserversorgung, 1889, p. 1126.

A record of experiments made at Zürich upon the effect of rate of

filtration, scraping, and the influence of vaulting. Rate and vaulting

were found to be without effect, but poorer results followed scraping.

The numbers of bacteria in the lake-water were too low to allow

conclusive results.

—— Journal für Gas- und Wasserversorgung, 1891, p. 684.

A farther account of the Zürich results, with full analyses and a

criticism of Fränkel and Piefke’s experiments.

BOLTON. Pamphlet, 1884.

Descriptions and statistics of London filters.

BÖTTCHER and OHNESORGE. Zeitschrift für Bauwesen, 1876, p. 343.

A description of the Bremen works, with full plans.

BURTON. Water-supply of Towns. London, 1894.

Pages 94-115 are upon filtration and mention a novel method of

regulating the rate.

CODD. Engineering News, Apr. 26, 1894.

A description of a filter at Nantucket, Mass.

CRAMER. Centralblatt für Bauwesen, 1886, p. 42.

A description of filters built at Brieg, Germany.

CROOK. London Water-supply. London, 1883.

DELBRUCK. Allgemeine Bauzeitung, 1853, p. 103.

A general article on filtration; particularly valuable for notices of

early attempts at filtration and of the use of alum.

Deutsche Verein von Gas- und Wasserfachmänner.

Stenographic reports of the proceedings of this society are printed

regularly in the _Journal für Gas- und Wasserversorgung_, and the

discussions of papers are often most interesting.

DROWN. Journal Association Eng. Societies, 1890, p. 356.

Filtration of natural waters.

FISCHER. Vierteljahresschrift für Gesundheitspflege, 1891, p. 82.

Discussion of papers on water-filtration.

FRÄNKEL. Vierteljahresschrift für Gesundheitspflege, 1891, p. 38.

On filters for city water-works.

FRÄNKEL and PIEFKE. Zeitschrift für Hygiene, 1891, p. 38, Leistungen

der Sandfiltern.

E. FRANKLAND. Report in regard to the London filters for 1893

in the Annual Summary of Births, Deaths, and Causes of Death in

London and Other Great Towns, 1893. Published by authority of the

Registrar-General.

P. FRANKLAND. Proc. Royal Society, 1885, p. 379.

The removal of micro-organisms from water.

—— Proceedings Inst. Civil Engineers, 1886, lxxxv. p. 197.

Water-purification; its biological and chemical basis.

—— Trans. of Sanitary Institute of Great Britain, 1886.

Filtration of water for town supply.

FRÜHLING. Handbuch der Ingenieurwissenschaften, vol. ii.

Chapter on water-filtration gives general account of filtration, with

details of Königsberg filters built by the author and not elsewhere

published.

FULLER. Report Mass. State Board of Health, 1892, p. 449.

Report Mass. State Board of Health, 1893, p. 453.

Accounts of the Lawrence experiments upon water-filtration for 1892

and 1893.

—— American Public Health Association, 1893, p. 152.

On the removal of pathogenic bacteria from water by sand filtration.

—— American Public Health Association, 1894, p. 64.

Sand filtration of water with special reference to results obtained at

Lawrence, Mass.

GILL. Deutsche Bauzeitung, 1881, p. 567.

On American rapid filters. The author shows that they are not to be

thought of for Berlin, as they would be more expensive as well as

probably less efficient than the usual procedure.

—— Journal für Gas- und Wasserversorgung, 1892, p. 596.

A general account of the extension of the Berlin filters at Müggel. No

drawings.

GRAHN. Journal für Gas- und Wasserversorgung, 1877, p. 543.

On the filtration of river-waters.

—— Journal für Gas- und Wasserversorgung, 1890, p. 511.

Filters for city water-works.

—— Vierteljahresschrift für Gesundsheitpflege, 1891, p. 76.

Discussion of papers presented on filtration.

—— Journal für Gas- und Wasserversorgung, 1894, p. 185.

A history of the “Rules for Water-filtration” (Appendix I), with some

discussion of them.

GRAHN and MEYER. Reiseberichte über künstliche central Sandfiltration.

Hamburg, 1876.

An account of the observations of the authors in numerous cities,

especially in England.

GRENZMER. Centralblatt der Bauverwaltung, 1888, p. 148.

A description of new filters at Amsterdam, with plans.

GRUBER. Centralblatt für Bakteriologie, 1893, p. 488.

Salient points in judging of the work of sand-filters.

HALBERTSMA. Journal für Gas- und Wasserversorgung, 1892, p. 43.

Filter-works in Holland. Gives sand, gravel, and water thickness, with

diagrams.

—— Journal für Gas- und Wasserversorgung, 1892, p. 686.

Description of filters built by the author at Leeuwarden, Holland,

with plans.

HART. Proceedings Inst. of Civil Engineers, 1890, c. p. 217.

Description of filters at Shanghai.

HAUSEN. Journal für Gas- und Wasserversorgung, 1892, p. 332.

An account of experiments made for one year with three 16-inch filters

at Helsingfors, Finland, with weekly analyses of effluents.

HAZEN. Report of Mass. State Board of Health, 1891, p. 601.

Experiments upon the filtration of water.

—— Report of Mass. State Board of Health, 1892, p. 539.

Physical properties of sands and gravels with reference to their use

in filtration. (Appendix III.)

HUNTER. Engineering, 1892, vol. 53, p. 621.

Description of author’s sand-washing apparatus.

KIRKWOOD. Filtration of River-waters. New York, 1869.

A report upon European filters for the St. Louis Water Board in 1866.

Contains a full account of thirteen filtration-works visited by the

author, and of a number of filter-galleries, with a project for

filters for St. Louis. This project was never executed, but the report

is a wonderful work which appeared a generation before the American

public was able to appreciate it. It was translated into German, and

the German edition was widely circulated and known.

KOCH. Zeitschrift für Hygiene, 1893.

Water-filtration and Cholera: a discussion of the Hamburg epidemic of

1892 in reference to the effect of filtration.

KRÖHNKE. Journal für Gas- und Wasserversorgung, 1893, p. 513.

An account of experiments made at Hamburg, as a result of which the

author recommends the addition of cuprous chloride to the water before

filtration to secure greater bacterial efficiency.

KÜMMEL. Journal für Gas- und Wasserversorgung, 1877, p. 452.

Operation of the Altona filters, with analyses.

—— Vierteljahresschrift für Gesundheitspflege, 1881, p. 92.

The water-works of the city of Altona.

—— Journal für Gas- und Wasserversorgung, 1887, p. 522.

An article opposing the use of rapid filters (David’s process).

—— Journal für Gas- und Wasserversorgung, 1890, p. 531.

A criticism of Fränkel and Piefke’s results, with some statistics of

German and English filters. (The English results are taken without

credit from Kirkwood.)

—— Vierteljahresschrift für Gesundheitspflege, 1891, p. 87.

Discussion of papers on filtration, with some statistics.

—— Vierteljahresschrift für Gesundheitspflege, 1892, p. 385.

The epidemic of typhoid-fever in Altona in 1891.

—— Journal für Gas- und Wasserversorgung, 1893, p. 161.

Results of experiments upon filtration made at Altona, and bacterial

results of the Altona filters in connection with typhoid death-rates.

—— Trans. Am. Society of Civil Engineers, 1893, xxx. p. 330.

Questions of water-filtration.

LESLIE. Trans. Inst. Civil Engineers, 1883, lxxiv. p. 110.

A short description of filters at Edinburgh.

LINDLEY. A report for the commissioners of the Paris Exposition of

1889 upon the purification of river-waters, and published in French

or German in a number of journals, among them _Journal für Gas- und

Wasserversorgung_, 1890, p. 501.

This is a most satisfactory discussion of the conditions which modern

experience has shown to be essential to successful filtration.

MASON. Engineering News, Dec. 7, 1893.

Filters at Stuttgart, Germany, with plans.

MEYER and SAMUELSON. Deutsche Bauzeitung, 1881, p. 340.

Project for filters for Hamburg, with diagrams. Except in detail, this

project is the same as that executed twelve years later.

MEYER. Deutsche Bauzeitung, 1892, p. 519.

Description of the proposed Hamburg filters, with diagrams.

—— The Water-works of Hamburg.

A paper presented to the International Health Congress at Rome, March

1894, and published as a monograph. It contains a full description of

the filters as built, with drawings and views in greater detail than

the preceding paper.

MILLS. Special Report Mass. State Board of Health on the Purification

of Sewage and Water, 1890, p. 601.

An account of the Lawrence experiments, 1888-1890.

—— Report Mass. State Board of Health, 1893, p. 543.

The Filter of the Water-supply of the City of Lawrence and its Results.

—— Trans. Am. Society of Civil Engineers, 1893, xxx. p. 350.

Purification of Sewage and Water by Filtration.

NEVILLE. Engineering, 1878, xxvi. p. 324.

A description of the Dublin filters, with plans.

NICHOLS. Report Mass. State Board of Health, 1878, p. 137.

The filtration of potable water.

OESTER. Gesundheits-Ingenieur, 1893, p. 505.

What is the Rate of Filtration? A purely theoretical discussion.

ORANGE. Trans. Inst. Civil Engineers, 1890, c. p. 268.

Filters at Hong Kong.

PFEFFER. Deutsche Bauzeitung, 1880, p. 399.

A description of filters at Liegnitz, Germany.

PIEFKE. Results of Natural and Artificial Filtration. Berlin, 1881.

Pamphlet.

—— Journal für Gas- und Wasserversorgung, 1887, p. 595. Die Principien

der Reinwassergewinnung vermittelst Filtration.

A sketch of the theory and practical application of filtration.

—— Zeitschrift für Hygiene, 1889, p. 128. Aphorismen über

Wasserversorgung.

A discussion of the theory of filtration, with a number of experiments

on the thickness of sand-layers, etc.

PIEFKE. Vierteljahresschrift für Gesundheitspflege, 1891, p. 59.

On filters for city water-works.

FRÄNKEL and PIEFKE. Zeitschrift für Hygiene, 1891, p. 38.

Leistungen der Sandfiltern. An account of the partial obstruction of

the Stralau filters by ice, and a typhoid epidemic which followed.

Experiments were then made upon the passage of cholera and typhoid

germs through small filters.

PIEFKE. Journal für Gas- und Wasserversorgung, 1891, p. 208. Neue

Ermittelungen über Sandfiltration.

The above mentioned experiments being objected to on certain

grounds, they were repeated by Piefke alone, confirming the previous

observations on the passage of bacteria through filters, but under

other conditions.

—— Zeitschrift für Hygiene, 1894, p. 151, Über Betriebsführung von

Sandfiltern.

A full account of the operation of the Stralau filters in 1893, with

discussion of the efficiency of filtration, etc.

PLAGGE AND PROSKAUER. Zeitschrift für Hygiene, 11. p. 403.

Examination of water before and after filtration at Berlin, with

theory of filtration.

REINCKE. Bericht über die Medicinische Statistik des Hamburgischen

Staates für 1892.

Contains a most valuable discussion of the relations of filtration to

cholera, typhoid fever, and diarrhœa, with numerous tables and charts.

(Abstract in Appendix II.)

REINSCH. Centralblatt für Bakteriologie, 1895, p. 881.

An account of the operation of the Altona filters. High numbers of

bacteria in the effluents have often resulted from the discharge of

sludge from the sedimentation-basins onto the filters, due to the

interference of ice on the action of the floating outlet for the

basins, and this, rather than the direct effect of cold, is believed

to be the direct cause of the low winter efficiency. The author urges

the necessity of a deeper sand-layers in no case less than 18 inches

thick.

RENK. Gesundheits-Ingenieur, 1886, p. 54.

—— Über die Ziele der künstliche Wasserfiltration.

RUHLMANN. Wochenblatt für Baukunde, 1887, p. 409.

A description of filters at Zürich.

SALBACH. Glaser’s Annalen, 1882.

Filters at Groningen, Holland, built in 1880. Alum used.

SAMUELSON. Translation of Kirkwood’s “Filtration of River-waters” into

German, with additional notes especially on the theory of filtration

and the sand to be employed. Hamburg, 1876.

SAMUELSON. Filtration and constant water-supply. Pamphlet. Hamburg,

1882.

—— Journal f. Gas- und Wasserversorgung, 1892, p. 660.

A discussion of the best materials and arrangement for sand-filters.

SCHMETZEN. Deutsche Bauzeitung, 1878, p. 314.

Notice and extended criticism of Samuelson’s translation of Kirkwood.

SEDDEN. Jour. Asso. Eng. Soc., 1889, p. 477.

In regard to the sedimentation of river-waters.

SEDGWICK. New England Water-works Association, 1892, p. 103.

European methods of Filtration with Reference to American Needs.

SOKAL. Wochenschrift der östreichen Ingenieur-Verein, 1890, p. 386.

A short description of the filters at St. Petersburg, and a comparison

with those at Warsaw.

STURMHÖFEL. Zeitschrift f. Bauwesen, 1880, p. 34.

A description of the Magdeburg filters, with plans.

TOMLINSON. American Water-works Association, 1888.

A paper on filters at Bombay and elsewhere.

TURNER. Proc. Inst. Civil Engineers, 1890, c. p. 285.

Filters at Yokohama.

VAN DER TAK. Tijdschrift van de Maatschapping van Bouwkunde, 1875(?).

A description (in Dutch) of the Rotterdam water-works, including the

wooden drains which caused the trouble with crenothrix, and which have

since been removed. Diagrams.

VAN IJSSELSTEYN. Tijdschrift van het Koninklijk Instituut van

Ingenieurs, 1892-5, p. 173.

A description of the new Rotterdam filters, with full drawings.

VEITMEYER. Verhandlungen d. polyt. Gesell. zu Berlin, April, 1880.

Filtration and purification of water.

WOLFFHÜGEL. Arbeiten aus dem Kaiserliche Gesundheitsamt, 1886, p. 1.

Examinations of Berlin water for 1884-5, with remarks showing superior

bacterial efficiency with open filters.

—— Journal für Gas- u. Wasserversorgung, 1890, p. 516.

On the bacterial efficiency of the Berlin filters, with diagrams.

ZOBEL. Zeitschrift des Vereins deutsche Ingenieure, 1884, p. 537.

Description of filters at Stuttgart.

OTHER LITERATURE.

Many scientific and engineering journals publish from time to time

short articles or notices on filtration which are not included in the

above list. Among such journals none gives more attention to filtration

than the _Journal für Gasbeleuchtung und Wasserversorgung_, which

publishes regularly reports upon the operation of many German filters,

and gives short notices of new construction. The first articles upon

filtration in this journal were a series of descriptions of German

water-works in 1870-73, including descriptions of filters at Altona,

Brunswick, Lübeck, etc. Stenographic reports of many scientific

meetings have been published, particularly since 1890, and since 1892

there has been much discussion in regard to the “Rules for Filtration”

given in Appendix I.

A Report of a Royal Commission to inquire into the water-supply of the

metropolis, with minutes of evidence, appendices, and maps (London,

1893-4), contains much valuable material in regard to filtration.

The monthly reports of the water examiner, and other papers published

by the Local Government Board, London, are often of interest.

The German “Verein von Gas- u. Wasserfachmänner” prints without

publishing a most useful annual summary of German water-works

statistics for distribution to members. Many of the statistics given in

this volume are from this source.

Description of the filters at Worms was given in the _Deutsche

Bauzeitung_, 1892, p. 508; of the filters at Liverpool in

_Engineering_, 1889, p. 152, and 1892, p. 739. The latter journal also

has given a number of descriptions of filters built in various parts of

the world by English engineers, but, excepting the articles mentioned

in the above list, the descriptions are not given in detail.

The water companies have large storage and sedimentation basins with