Septic Tanks
A septic tank treats domestic
sewage and discharge, either into a watercourse or into the ground. In septic tanks the solids in the sewage settle to the
bottom. Relatively clear liquid is left which forms a layer of scum on its surface. Bacteria feed on this liquid and digest
some of the matter in it. The liquid then either passes into another settlement tank before passing to a watercourse or is
discharged underground through a network of pipes to filter through the soil. Septic tanks are capable of treating all of
a household's domestic sewage. However, the solids that build up at the bottom of the tank do need to be pumped out about
once a year.
If the tank serves only your
house then you alone are responsible for maintaining and emptying the tank. If several houses share the tank then the responsibility
is normally shared between the owners.
If you rent your house privately,
either you or your landlord may be responsible. We advise you to check your tenancy agreement to see who is responsible.
The process of digestion in
the septic tank is done by bacteria. These bacteria can be killed by certain chemicals. Too much bleach, detergents and other
household chemicals may destroy the useful bacteria. As a result the sewage will not be treated fully and may cause pollution
problems. Emptying the septic tank regularly will ensure the septic tank keeps working properly.
Most companies who will empty
your tank can be found under Waste Disposal Services in the Yellow Pages.
If a septic tank is too small
for the amount of sewage it takes and discharges to a stream or river it may be causing pollution.
Old brick tanks and cracked
glass fibre tanks will sometimes let ground water in. This often happens during the winter when the water table is higher.
The extra water means that the tank will have to be emptied more frequently. The faulty tank will also allow sewage to leak
outwards. It is an offence to allow a tank to overflow and the Environmental Protection Section would require that the tank
be repaired or emptied.
If your tank discharges its final effluent to a watercourse you will need to obtain Consent for Discharge from the Environment
Agency (EA). The EA sets standards for quality of effluent that can be allowed to enter rivers and streams. The quality
of watercourse is monitored by the EA and they may take legal action againist anyone who causes pollution.
