A septic tank if working correctly should not at any anytime overflow. The level should remain constant at the base of the outlet pipe (see The Operation of a Septic Tank) and as shown below in the drawing of a simple septic tank unit.

Septic Tank

If your tank is overflowing you need to check if you have been de-sludging on an annual basis. If you have, then it is likely that there is a problem with the system.

  1. If you are lucky there may be a blockage or build up of debris on the outlet T pipe, a simple de-sludge should solve the problem.
  2. If the soakaway is no longer effective, (see How Does a Soakaway Work) it may have come to the end of it's useful life and a new soakaway will need to be installed.
  3. The septic tank may be undersized for the current usage. If the tank was built in the 1930's then it was not designed for the dishwasher or the en-suite shower! A new septic tank or sewage treatment plant may need to be considered.

Please return to Septic Tank Help Page