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2020 septic tank regulations – England and Wales

Septic tank regulations for both England and Wales are set to change as of January 1, 2020.
All septic tank types that discharge to surface water will require either upgrading or replacement with a sewage treatment plant.

Current general binding rules: small sewage discharge to a surface water explained

As of January 1, 2015, new rules relating to sewage treatment discharge came into effect. If your system was installed and discharging prior this date, you have what is called an ‘existing discharge’. If it was installed and discharging after this date, you have a ‘new discharge’.

In the past, you were able to discharge the effluent from a septic tank in two ways. Either to a soakaway system or directly to a waterway.

Soakaway system:

The wastewater is released through a network of pipes in surrounding sub-soils, providing an additional form of treatment for the effluent from the septic tank. This helped ensure that the sewage water being dispersed did not cause pollution. Septic tanks discharging into a soakaway are not affected by 2020 septic tank regulations.


The effluent flows through a pipe directly into a stream, a river or a lake. The new rules do affect the direct discharge to a waterway as they state that direct discharge from a septic tank into a watercourse will no longer be permitted.

Timeframe for new septic tank regulations

Under new guidelines, this upgrade to your sewage treatment system must be in place by January 1, 2020, or when you sell the property (if selling before this date).
If the Environmental Agency finds that you are currently polluting surface water as a result of discharge from a septic tank, you will be required to install a new system before 2020. You generally will be given one year to upgrade, although this will be done on a case by case basis.

Rules for existing and new sewage treatment systems

This section examines how the implementation of these new septic tank regulations will impact upon pre-existing septic tank units as well as new installations.

Treatment system options

If you are discharging to a watercourse, such as a river or a stream, you are required to use a small sewage treatment plant (a.k.a. package treatment plant). This uses mechanical parts to clean the wastewater so that it does not pollute the river or stream.

People who are discharging to a surface water have been given three options:

  1. Connect to the main sewer. However, this is unavailable in a lot of remote areas.
  2. Install a drainage field or soakaway system. This is also known as an infiltration system and allows the septic tank to discharge to the ground instead of the surface water. Do note that, in many cases, the installation of a soakaway is not possible due to site constraints such as space and/or the soil not having sufficient soakaway potential such clay soil.
  3. Upgrade your septic tank with a small sewage treatment plant, eliminating the need for any drainage field. The Tricel Novo would suit this situation perfectly. It is a reliable, cost-effective solution that will allow you to comply with environmental legislation.
Tricel Novo sewage treatment plant

Required regulatory standards for systems

Your sewage treatment system is obligated to be of a required standard under this new septic tank regulations.

For small sewage treatment plants, the standard is BS EN12566. This standard consists of seven main parts:

  • Part 1: Prefabricated septic tanks – requirements and best practices for these units.
  • Part 2: Soil infiltration systems – discusses the design parameters, building specifications and implementation.
  • Part 3: Packaged and/or assembled domestic sewage treatment plants – the requisites and testing techniques used to gauge packaged sewage treatment plants that are necessary to treat sewage to the required quality.
  • Part 4: Septic tanks assembled in-situ from prefabricated kits – the standards and measurement sizes, including resistance to water leaks, pipe dimensions and grading of conformity.
  • Part 5: Pre-treated effluent filtration systems – a guide discussing design parameters, building information and component requisites for treating effluent.
  • Part 6: Prefabricated treatment units for septic tank effluent – the requirements, testing practices and grading of conformity for prefabricated secondary treatment units.
  • Part 7: Prefabricated tertiary treatment units – the requirements, testing practices and grading of conformity for a packaged and/or site assembled tertiary treatment unit.

For drainage fields, the standard is BS 6297:2007.

Capacity dependent upon requirements

When installing a new sewage treatment plant, you must check with “British Water Flows and Loads 4 guidance” to ensure that it meets sizing requirements. Your treatment system must be able to handle the largest amount of sewage that it will need to treat.

Maintenance of sewage treatment systems

You must remove built-up sludge from your sewer tank before it reaches its maximum capacity. This removal must be undertaken by a registered waste carrier. It is also required to service your treatment system in line with the manufacturer’s guidelines to ensure that it continues to deal with waste in a clean and efficient manner. If there are any damage or cracks in your system, you are obligated to have it repaired by a competent person.

Additional rules for systems installed and in use on or after January 1, 2015

These regulations apply to you if:

  • you started a new discharge from a small sewage treatment plant on or after January 1, 2015.
  • you had a discharge to ground before January 1, 2015, which you now want to change to discharge to a surface water (or the other way around).

Public sewers

If you are within 30m to a public sewer, then you will not be allowed to start a new discharge from your sewage treatment plant. For developments and multiple properties, this distance is multiplied by the number of properties. For example, if there are four properties the distance is increased to 4 x 30 meters = 120 metres.

If there is a valid reason prohibiting you from connecting to the public sewer and use a sewage treatment system instead, you must apply to the Environment Agency for a permit.

Planning approval

You are required to have planning permission and Building Regulations approval if you have or are planning to install a new sewage treatment plant.

Sensitive areas

You must apply for a permit if you want to begin a new discharge to a surface water in or within 500m of a designated sensitive area. A sensitive area includes special conservation sites, designated bathing water, protected shellfish water or special protection areas.

You also need a permit if the discharge is within 200m of an aquatic local nature reserve, or within 50m of a chalk river or aquatic local wildlife site.

You must contact the Environment Agency to check if you are in or near a designated sensitive area.

Surface water flow

Your new discharge must go to an area that has water flow year-round. It will not be allowed flow to watercourses that seasonally dry up.

Partial drainage fields

A partial drainage field is a system for discharging to water, which allows effluent to drain into the ground when levels in the watercourse are low, and into the watercourse when groundwater levels are high. A partial drainage field can only be used with a small sewage treatment plant and must be within 10m of the edge of the watercourse.

What to do next?

If you affected by the 2020 septic tank regulations, contact us to book your site visit, request and quote or advise you on the best course of actions for your project.

Regulating agencies

For England and Wales, visit the Environment Agency’s website to read the General binding rules: small sewage discharge to a surface water.

Different rules apply for Northern Ireland and Scotland, check with the following authorities for further details: the Scottish Environment Protection Agency or  Department of Agriculture, Environment and Rural Affairs if your property is located in Northern Ireland.

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