Septic tanks – digesting the new rules

23 December 2019

If you own or are buying (or selling) a property with a septic tank you need to be aware of what the rules mean for you.

What is changing and might it affect me?

Under the Environmental Permitting (England and Wales) Regulations 2016 (the Regulations), it is an offence to release (discharge) liquid into surface waters (e.g. a river, stream or lake) or to the ground without an environmental permit or exemption. In England, small domestic sewage discharges can qualify for an exemption. This exemption used to cover both septic tanks which discharged to the ground and into surface waters. However, since 1 January 2015, the Environmental Agency (EA) has not allowed new septic tanks to discharge into surface waters. Therefore, septic tanks which discharge directly into surface waters no longer qualify for an exemption. Conversely, if a septic tank discharges to the ground it could still qualify for an exemption. This is provided it meets all other requirements under the Regulations. Under the Regulations, a septic tank must also meet all rules specified in the document entitled “General binding rules for small sewage discharges” issued by the EA (the General Binding Rules).

You are responsible to upgrade your system as soon as possible if you are an operator of a septic tank which discharges directly into a surface water. You are an ‘operator’ if you own property that uses such a septic tank, shares it with another property (e.g. a neighbour), or are responsible for it under a written agreement (e.g. a tenancy). Under the EA guidance, if you are buying or selling a property with a septic tank, this responsibility should be addressed between the buyer and seller in the sale contract.

What can I do to make sure I am compliant?

If you have a septic tank that discharges directly into a surface water you must upgrade or replace it as soon as possible. You must have plans in place to carry out this work within a reasonable timescale, typically 12 months. The EA guidance outlines potential options. You may be able to:

  • connect to a mains sewer, where this is available; or
  • install a drainage field, so the septic tank discharges to the ground instead; or
  • replace the septic tank with a small sewage treatment plant; or
  • apply for an environmental permit. However, the EA guidance warns that a permit is only granted in exceptional circumstances.

For clarity, you cannot use a septic tank conversion unit or a reed bed for discharging effluent to a watercourse under the General Binding Rules. 

Once the septic tank has been upgraded or replaced, it must be compliant with both the Regulations and the General Binding Rules. It is worth noting the following key points in relation to all septic tanks.

  • The sewage must only be domestic.
  • It must not cause pollution. 
  • The treatment system must meet the relevant British Standards in force at the time of installation.
  • It must be installed correctly, be regularly maintained and have the right capacity. Note that you must apply for a permit if you are discharging more than 5 cubic metres (5,000 litres) per day.
  • If the property is sold or let, you must give the new operator written notice that a small sewage discharge is being carried out, along with a description of the system.

However if a new septic tank or treatment plant is installed and in use on or after 1 January 2015, there are additional rules to follow. These include the following important points.

  • For a single dwelling, the septic tank (or any part of the property) should not be within 30 metres of a public sewer. However for multiple dwellings, this distance must be multiplied by the number of properties.
  • All the necessary planning permissions and building regulations should be in place.
  • The discharge point must not be within or near a designated sensitive area (e.g. special areas of conservation or special protection areas). 
  • The discharge (permitted only in the case of a treatment plant) must be made into surface waters that normally have flow throughout the whole year.

If a septic tank meets all requirements under the Regulations and the General Binding Rules, it should qualify for an exemption. 

This article does not cover the requirements of other sewage systems, such as small sewage treatment plants or septic tanks that discharge to the ground. The content of this article is for general information only. For specific advice please contact a member of Birketts' Agriculture and Estates team

This article is an updated version of our original article (published on 3 October 2019), following an update of the Environment Agency guidance on 25 October 2019.


Faye Milton

Trainee Solicitor

+44 (0)1603 756552


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