A septic tank when first used does not need starters, such as yeast,
to promote bacterial action. A good septic tank normally requires no
maintenance other than a yearly inspection and an occasional cleaning.
Frequency of cleaning depends on the capacity of the tank and the
quantity and composition of the sewage. Tanks of the size recommended
in this bulletin may require cleaning at intervals of 3 to 5 years.
The tank should be cleaned when 18 to 20 inches of sludge and scum has
accumulated. If a drain has not been provided, sludge may be removed by
bailing or by pumping with a sludge or bilge pump. It is not necessary
to remove the entire liquid contents. Burial in a shallow pit or trench
with at least 18 to 24 inches of earth cover at a point remote from
water sources is the most practical method for disposing of these
wastes.
A septic tank is intended to handle sewage only. Coffee grounds and
ground garbage may be included if there is an ample supply of water for
flushing and the tank is cleaned more frequently than would otherwise
be done. The size of the tank should be increased at least 25 percent
if these materials are included in the sewage.
=_Do not use matches or an open flame to inspect a septic tank, as
the gasses produced by decomposing sewage may explode and cause
serious injury._=