A simple septic tank system consists of a tank and a soak away drain. Our septic tank design is a two chamber system which retains sewage from a property for sufficient time to allow the solids to form at the base of the tank, where it is partially broken down. The remaining liquid in the tank then drains from the tank by means of an outlet pipe.

Design Considerations

The tank should be sized sufficiently to ensure that any fluid is retained in the tank for the specified retention period stated under local regulations.

Internal Compartments

The compartment or baffle plate ensures that when the influent enters the tank, solids are dropped as the liquid loses velocity. Secondly it makes certain that the route from inlet to outlet is not direct ensuring that liquid circulates and retention time is increased.

Inlet and outlet pipes

In order to prevent blockages the inlet pipe should be slightly higher than the outlet pipe (approx 50 –100mm or 2 – 4 inches)

Maintenance

One of the most obvious forms of maintenance is the emptying of the tank. In order to get this carried out you need to acquire a Discharge Consent under the Water (Northern Ireland) Order 1999. Contractors carrying out this work have Service Conditions for this service and these can be obtained from the Northern Ireland Water Board Website under publication ‘Septic Tank, Domestic Treatment Plant and Cesspool Services’. It is important to follow these guidelines as a grant to discharge is an important legal document which you will be required to produce if you are selling your property.