If your domestic property has no connection to a foul sewer, and no connection is possible, you will most likely have a septic tank to deal with sewage and wastewater from your premises. This might be a septic tank that deals only with the wastewater from your house, or it might be a septic tank that deals with wastewater from a number of neighbouring properties.

Septic tanks use natural biological processes to break down sewage and wastewater, and produce a discharge that can be made safe and harmless when slowly added to well aerated soil, or by another final treatment.

If the natural processes in the septic tank are stopped, then problems can occur. Non-mains sewerage systems can pollute groundwater (all water lying below the water table or in aquifers) if they are poorly located, built or operated. This can affect water supplies, such as drinking water or water for livestock. It can also pollute surface water in rivers, streams and lochs/loughs.

This guide explains what you should do to look after a septic tank and how to prevent problems arising. It also tells you how to register existing or new septic tanks.

If you are a plumber or builder installing a septic tank there are certain things you must do before installing a tank. This guideline outlines these responsibilities and the authorisation you need before you start work.

NOTE: In England there are new rules that apply to new septic tanks that discharge directly to water (e.g. a river or stream) . These new rules do not apply in Scotland or Northern Ireland.