WATER-SUPPLY FROM WELLS AND TANKS.
[Sidenote: Registering wells.]
[Sidenote: Cleaning and repairing wells.]
In order to obtain a comparatively pure water-supply, under
circumstances existent in most bazaars, it is essential that the spill
water from wells be led away by properly constructed drains beyond what
is known as the cone of filtration; this may be described as a circle
drawn round the mouth of the well, the radius being equal to the depth
of it. Owing to Indian customs, there is always a considerable quantity
of spill water in the vicinity of a well, and this, when proper
platforms and drains are not constructed, finds its way back, after
contamination, by the line of least resistance, either down the sides of
the masonry lining, or by cracks and fissures in the ground. For water
supplies from wells and tanks the main object is to prevent any water
once drawn out, again, after probable contamination, flowing back into
the source of supply. Arrangements should be made for registering every
well in a municipality where this has not already been done, and for
taking over, or closing all those the owners refuse, or fail to put in a
proper sanitary state. In Bengal this can be enforced under section 200
of the Bengal Municipal Act (1894). A copy of the map of a ward showing
the position of all wells and tanks therein is given in Fig. 3. The Well
Register, which should be corrected yearly, is given in Appendix C, page
62. It is impossible in most cases, owing to large numbers, for a
Municipality to take over, repair, and conserve all the wells (in the
town of Muzaffarpur, there were 718 wells) but much good can be done by
acquiring a certain number of the most useful unowned ones, and making
the owners of others, when in a position to do so, put and maintain them
in a sanitary state. When new wells are sunk, the owner must be made to
construct them according to a standard design. Fig. 4 shows an
inexpensive and good form of open well, top, and platform. From the
experience of ten years in the Muzaffarpur District (from 1891 to 1901),
where wells on the sides of main roads were so treated, this is
possible. Some 400 wells on 725 miles of road were taken over by the
District Board, put in a proper state of repair, suitable platforms and
spill-water drains constructed, and arrangements made for annual
cleaning out and disinfecting with permanganate of potash during the hot
weather months. These were eventually greatly appreciated, and, whereas
in the first instance difficulties were experienced in getting hold of
suitable ones, it was of late years necessary to make careful selections
from the applications received. In addition to this, the owners of
numerous ones, on whom notice was served that if they did not put them
in a sanitary condition, they would be taken over and repaired by the
District Board, elected to do the work on the prescribed lines at their
own expense. It is a notable fact that cholera when prevalent in
villages close by, frequently is not found in those where these wells
are situated. This organization is being extended to villages which have
an especially bad sanitary record. For easy reference the Instructions
for Repairing, Cleaning and Disinfecting Wells are quoted.
[Illustration:
MUZAFFARPUR MUNICIPALITY
WARD Nº 11
FIG. 3.
]
_Repairing._
1. The ground round a well must first be excavated to a depth of at
least 5 feet below surface level, and for a width of 5 feet round the
well and sealed with puddled clay, the well lining being first rebuilt
from this level where necessary, and continued up for a height of 2 feet
6 inches above ground-level; the top of the well must be sloped off to
prevent vessels being placed on it, and consequent splashing getting
back into the well. A properly made platform resting on suitable
foundations, must be built round the well at 1 foot above at its highest
point, and sloping off to ground-level at its lowest, with a ridge round
it to prevent spill-water draining away indiscriminately and an opening
at its lowest point, leading into a pucca drain, constructed with a
suitable fall, and continued until natural drainage is reached, or
outside the cone of filtration, so as to prevent any water lodging in
the vicinity of the well.
2. A closed-in top prevents dust, which may convey pathogenic germs,
gaining access to the water.
_Cleaning._
3. Wells should be dewatered, and cleaned out at least once every year.
The sides must be scraped, and all mud, broken earthen vessels, etc.,
removed; _quicklime_ must then be applied to the sides and bottom of the
wells.
4. The only suitable time to clean out wells is during the hot weather
as the water in them is then at its lowest level.
5. All wells must be cleaned out down to the well-curb or “Jamot.”
_Disinfecting._
6. Permanganate of potassium is a crystalline salt-like substance of a
purple colour, in the preparation of which only mineral substances are
employed.
[Illustration:
FIG. 4.
Well Top
]
[Illustration:
FIG. 5.
]
[Illustration:
FIG. 6.
]
7. Put one or two ounces of the solid substance into a _dol_, or bucket,
which has been filled with water drawn from the well about to be
treated. Stir it up, and pour the red solution thus produced into the
well, leaving the portion of permanganate that is not yet dissolved at
the bottom of the _dol_. Lower the _dol_ into the well, fill it with
water, draw it up, pour back the water as before, and repeat the process
till all the permanganate has been dissolved. In all cases enough
permanganate should be added to produce a faint red colour lasting for
24 hours.
8. If the water in the well is bad, more permanganate will be necessary.
In such a case it will be found that the strong red colour at first
produced quickly changes to brown, and then fades away. This is because
the permanganate destroys dirt and is destroyed by it. Therefore, if the
water in the well is clean, a smaller quantity of permanganate will be
necessary. From one to four ounces of permanganate will be found to be
enough for ordinary wells. If more permanganate is added than is enough
to produce a faint permanent red colour, it is likely that frogs, that
may be in the well, will be killed. This will, in a few days, give the
water a putrid taste. If the quantity of permanganate is not enough to
produce a faint permanent red colour, it is unlikely to do good. If
possible, the permanganate should be added at night, in order to leave
the wells undisturbed as long as possible. The water will be fit to
drink on the following morning. If then a red colour is still present,
the water may have an unpleasant taste, but it is perfectly harmless.
Figure 4 is an illustration of the latest pattern of well adopted.
[Sidenote: New Wells.]
When a new well is proposed, and local conditions are suitable, a safe
form is that designed by Dr. Cameron of Wigton, N. B. This arrangement
is shown in Fig. 5. The well should be in the centre of a reserved area
of at least 20 yards in diameter, and the lead pipe leading from it to
the pump must be fitted by brass screw joinings. This is a suitable
design for the vicinity of cutcherries, where an open space for a
reserved area is generally available.
Another excellent design for a new well, and one more generally
suitable, is shown in Fig. 6. This prevents any danger of the water
being contaminated by dirty vessels being lowered into it for the
purpose of drawing water.
[Illustration:
FIG. 7.
]
[Sidenote: Tube Wells.]
Tube wells answer admirably in many localities; it is, however, always
essential to have a bore hole made first to determine the stratum which
has to be tapped, as the point of the tube may be easily driven through
this. An improved form of pump is shown in Fig. 7; this obviates the
danger of impure water being put in the mouth of the pitcher spout pump
in order to make it draw.
The great advantage of tube wells is that they enable a stratum,
underlying that of impermeable stiff clay which exists in many cases, to
be tapped, thus avoiding the danger of contamination by subsoil water.
The supply from a tube well is, however, limited in quantity.
Where wells are founded on a clay stratum their efficiency can generally
be largely increased at a trifling cost, by driving a pipe lined boring
down until water-borne sand is met. Great care must, however, be taken
that, when the boring is going on, this stratum be not passed through,
and constant tests of the discharge obtained at the various depths are
therefore necessary.
[Sidenote: Water drawing utensils.]
In all cases it is advisable either to provide a pump on a public well,
or iron buckets with light chains and wooden pullies, so that private
water drawing vessels be not lowered into the water. The pump should be
fixed on the platform surrounding the well, and not on the top. A light
corrugated iron roof over the mouth of a well is also useful in
preventing leaves, and other impurities falling in, and also in
affording shelter to the water-drawers.
[Illustration:
PLAN OF DOME FOR WELL
FIG. 8.
]
An effective and economical well cover designed for Ranchi is shown in
Fig. 8, page 11. This, for a 8′ diameter well, costs about Rs. 90.
[Sidenote: Tanks.]
A large proportion of the water-supply of a Municipality is usually
taken from tanks, into most of which the drainage water from the
neighbouring vicinity is washed during the rainy season. This can be
prevented by raising the banks. The sullage water of a bazaar is
indescribably filthy, and if in-drainage is prevented the tanks will
fill up by percolation as the level of the subsoil water rises—a bad
enough source of supply, but infinitely purer than the surface water
combined with filth from a crowded area. The excavation of new tanks in
a Municipality should be discouraged as much as possible, and attention
paid to conserving the existing ones. Small pumps and masonry platforms
for washing purposes draining away from the tanks will improve matters.
In the late Mr. A. E. Silk’s book on “Municipal Engineering in Bengal”
the following classification of comparative purity of water-supply is
adopted:—
1. Deep spring water.
2. Subterranean or deep well water.
3. Upland surface water.
4. Subsoil water. (If distant from any collection of houses).
5. Land springs.
6. River water.
7. Surface water from cultivated land.
8. Subsoil water under villages or towns.
Surface water from a bazaar is classified as sullage.
[Illustration:
FIG. 9.
]
Where tanks are used as a source of drinking water-supply, they should
be properly fenced and conserved, and the water drawn by a pump. Recent
researches have proved that polluted water, if stored in a tank or
reservoir where it can be preserved from subsequent contamination,
rapidly becomes pure. The Type plan, approved by the Sanitary Board of
Behar and Orissa, is shown in Fig. 9, page 13. This for an existing tank
of 100 yards square area is estimated to cost Rs. 2,700. The pumps,
provided in duplicate, are Kite double action pattern and cost about Rs.
425 each. The fencing provided is the Ideal Woven wire fence, 10
strands, 48″ high, and can be fixed at about 12 annas per yard.
Another and a cheaper method is shown in Fig. 10, page 15. Here the tank
is completely fenced in with the exception of an entrance to a platform
which extends towards the centre of the tank from which the water can be
drawn by hand. Model rules for clearing out and re-excavating tanks are
as follows:—
[Sidenote: Excavation.]
1. Tanks should be cleared out and re-excavated during the dry weather
months when the level of the subsoil water is at its lowest. Work should
be commenced in January or February and completed before the middle of
May, but these dates must depend more or less on the locality, as in
some parts of the Province the prevalence of heavy thunderstorms in May
might make it advisable to complete the work before then.
2. The re-excavation, until water-level is reached, should be carried
out in regular layers of 1 foot in depth, an offset of 1 foot being left
on the bank side for each layer. This, when dressed off, will give a
regular side slope of 1 to 1 to the tank. When water-level is reached,
if it be considered necessary to excavate below this, and if pumping
machinery to dewater the tank is unavailable, the area must be divided
up into compartments of suitable size, separated by bunds, one, or more
of which, can be dewatered by bailing into the adjacent ones, when the
excavation can be continued to the required depth, the other
compartments being similarly treated in turn.
[Illustration:
TYPE DESIGN FOR FENCING IN TANKS
FIG. 10.
]
[Sidenote: Disposal of Spoil.]
3. The spoil from the excavations should be placed on the outside of the
embankment formed round the tank when originally made, and should be
deposited in such a position to preclude, as far as possible, its being
washed back again by rain water.
[Sidenote: Dressing and Turfing.]
The crest of the embankment should be dressed off to a slope of 1 in 12
away from the tank, with side slopes on the outside of 2 to 1. This will
prevent direct contamination of the tank by spill water from the crest,
where persons or carts, may have encamped.
All slopes should be neatly dressed off; all those above highest
water-level being turfed during the commencement of the ensuing rainy
season. This is very important as it prevents the chance of a
considerable quantity of the excavated earth being washed back into the
tank.
Water-supply for Municipal and Rural areas is a subject which is, at the
present day, receiving much attention. It is being encouraged by
contributions from Government and from Local Authorities, by gifts from
wealthy Indian gentlemen, and by loans from Government redeemable in a
fixed period. For rules for the preparation of projects in the Province
of Behar and Orissa see Appendix F, page 69, and for the table of
instalments for the repayment of loans, Appendix E, page 68. The
comparative death-rate from Cholera and Intestinal diseases in
Municipalities which possess a pipe water-supply, and those without,
need only be glanced at to prove the vital importance of a pure
water-supply, and even these figures do not adequately indicate the true
position, as further loss of life due to water-borne diseases, cannot be
traced out from the statistics published. Major S. A. Harris, I.M.S.,
Sanitary Commissioner, United Provinces, in his paper on the effect of a
pipe water-supply on the reduction of Cholera in urban areas, read at
the Second All-India Sanitary Conference at Madras, in November 1912,
quotes the reduction of death-rate per mille before and after the
provision of a pipe water-supply for the following places:—
Before. After.
Dehra Dun 10·19 2·25
Meerut 7·49 3·02
Naini Tâl 10·19 2·86
and stated that the number of years in which the Cholera death-rate rose
above 1 per mille is seen to have been reduced by the filtered
water-supply to about ½ in Dehra Dun, Meerut, Benares, Lucknow and Naini
Tâl.
The cost of Water Works must vary considerably according to local
conditions. Where the supply is derived from a source not liable to
contamination, from spring wells, tube wells and infiltration galleries,
where subsequent filtration is unnecessary, the capital expenditure may
vary from Rs. 3 per head for a tube well, Rs. 4–8 from an infiltration
gallery supply, such as Congeeveram (Madras), to Rs. 10 and over for a
filtered water-supply derived from a river. The cost of the distribution
system must necessarily vary according to its size, and the density of
population in the area served, but this, under normal circumstances, may
be assumed at 50 per cent. of that of the Water Works. As each Province
in India has a Sanitary Engineer, and as the subject of the preparation
of a Water Works project is a highly technical one, it is beyond the
scope of this work to go further than to impress its importance. Any
efficient Water Works started means a large saving of human life and of
much misery.