Septic tanks and off-mains drainage in Wiltshire and Somerset, in numbers

A short history

The Environment Agency’s guide to the general binding rules was first published on 16 June 2015 ¹.

The rules have been updated several times. In 2019 the guide made clear that systems installed before 1983 need not meet the British Standard, but must meet the other rules ¹. On 31 July 2019 it noted that the guide applies only to England ¹. On 2 October 2023 the guide added general binding rules for discharges started on or after that date ¹. A discharge is “new” if it started or changed significantly on or after 2 October 2023 ³. The most recent change, on 23 July 2026, added requirements for discharges to ground engineered to reduce the percolation rate ¹.

If you connect to the mains sewer, you do not need a permit ³.

What it costs

The Environment Agency publishes charging guidance, last updated on 1 April 2026. It says the Agency does not recover the full cost of processing applications for sewage discharges of up to 5 cubic metres a day from domestic households and charities ². A “domestic household” here means premises exempt from business rates ².

If a mix of households, charities and other applicants make one discharge, the full application cost applies ². No annual charge applies when the permit allows 5 cubic metres a day or less and the holder is a householder or a charity ². The guidance says charges increase each 1 April by no more than the CPI inflation rate for the 12 months to September of the previous year ².

We found no published price for emptying, installing or servicing a system. Prices vary by firm.

Who checks the trade

• The Environment Agency. It regularly checks surface and groundwater quality and permit compliance. It grants or refuses permits, and may take enforcement action if pollution continues ¹.
• Building regulations and planning. The guide says you must have building regulations approval for a new septic tank and may also need planning permission. It does not say which body handles them ¹.
• Accredited service engineers. The guide refers to British Water’s list of approved equipment and its list of accredited service engineers ¹.
• Operator duties. You are the operator if you own the property using the system, or you share it with other properties (in which case you are jointly responsible), or you have an agreement with the owner such as a tenancy ³. The operator is responsible for meeting the rules ³.