If you have a septic tank that discharges into a stream or river you will have to replace or upgrade your treatment system as soon as possible.

In England, this obligation applies to residential properties and also to small businesses such as pubs, hotels and offices.

What types of septic tank are affected?

This requirement affects septic tanks dealing with small domestic sewage that discharge to surface water. In other words:

  • Domestic sewage means sewage from, for example, a toilet, bathroom, shower or kitchen but must not contain any trade effluent. It can also include discharges from some small businesses such as a pub, small hotel or small office premises, provided that they do not include trade effluent.
  • Surface water includes a stream, river, lake or estuary.

Where has the requirement come from?

This requirement has come from the Environment Agency (EA). Its guidance on small sewage discharge to surface water (link provided below) imposes the requirement where you have a septic tank that discharges directly to surface water. The guidance used to stipulate a date of 1 January 2020 but that deadline was removed in updated guidance published on 25 October 2019. It provides that property owners must have plans in place to carry out the work within a reasonable time, typically 12 months.

What can you do to comply with the EA septic tank requirement?

The EA guidance suggests the following options:

  • Connect to a public sewer where available (there may be a public sewer in the vicinity of the property that has been laid since the septic tank was installed).
  • Install a ‘drainage field’ (also known as an infiltration system) so that the septic tank can discharge to the ground instead – but note that other rules apply to this option.
  • Replace your septic tank with a small sewage treatment plant.  You must have building regulations approval if you want to install one of these and you may also need planning permission.

Can you apply for a permit to discharge to surface water instead?

The EA guidance indicates that you can apply for a permit but it is only granted in exceptional circumstances and you should contact them to discuss.

Where can you find out more about the EA guidelines?

The EA has guidance on small sewage discharge to surface water: https://www.gov.uk/guidance/general-binding-rules-small-sewage-discharge-to-a-surface-water and suggests that advice is obtained from an accredited service engineer.

What should you do if your property is not in England?

If your property is not in England, it is advised that you contact the EA for further information. There are different rules for septic tanks and treatment plants in Northern Ireland, Scotland and Wales.

Who is responsible for the cost of replacement or upgrading?

The EA guidance says that if you are buying or selling a property with this type of septic tank, you should agree with the buyer or seller who will be responsible for the replacement or upgrade and it should be addressed in the sale contract. It is recommended that you should therefore discuss this with your conveyancer.

Implications of not complying with the EA septic tank requirement

If your septic tank causes pollution at any time to the surface water, the EA has a range of enforcement measures at its disposal.