Septic Tank Regulations in England: The General Binding Rules Explained

Septic tank regulations in England come mainly from the Environment Agency's general binding rules for small sewage discharges. If your system meets every rule that applies to it, you don't need a permit. The headline rules are simple: a septic tank must drain to a drainage field, never straight to a ditch or stream; it must stay within the daily volume limit; it must be emptied and maintained; and a buyer must be told about it in writing. New systems also need building regulations approval under Part H. If your tank fails any of these, our septic tank installation and replacement service can bring it into line.

This guide covers England only. Wales, Scotland and Northern Ireland have separate rules.

What are the general binding rules for septic tanks?

The general binding rules are a set of conditions that let you run a septic tank or small sewage treatment plant without an environmental permit. Gov.uk publishes two versions: one for discharges to the ground, usually through a drainage field, and one for discharges to surface water, such as a river or stream.

They sit under the Environmental Permitting (England and Wales) Regulations 2016, which make a discharge of sewage effluent a regulated activity. Meeting the rules makes a small domestic discharge exempt from needing a permit. They apply only to domestic sewage, meaning waste from toilets, bathrooms, showers and kitchens, not trade effluent.

The gov.uk page for discharges to ground lists 16 rules, grouped by when the discharge started. The core rules apply to everyone; extra rules apply to discharges that started on or after 1 January 2015, and two more apply to new discharges from 2 October 2023.

Who is responsible for a septic tank?

The "operator" is responsible. Gov.uk says you are the operator if you own the property that uses the system, if you share the system with other properties (you are then jointly responsible), or if you have an agreement with the owner, such as a tenancy agreement, that makes you responsible.

If you're not sure whether you have a septic tank, a sewage treatment plant or a cesspool, gov.uk suggests asking a local installation or maintenance company. The type matters, because cesspools follow different rules; see cesspit vs septic tank.

What was the 1 January 2020 septic tank deadline?

The rules introduced in 2015 gave septic tanks that discharged straight into a watercourse until 1 January 2020 to be upgraded. Propertymark states plainly that the deadline "has already passed".

Current gov.uk guidance doesn't give a new date. It says that if your septic tank discharges directly to a watercourse, "as soon as possible you must" do one of three things:

1. Connect to a public foul sewer.
2. Replace the septic tank with a small sewage treatment plant.
3. Install a drainage field so the tank discharges to ground.

You "must have plans in place to do this work within a reasonable timescale, usually 12 months." Where several neighbouring homes all need to upgrade, gov.uk says your sewerage company may have a legal duty to provide a sewer, known as first time sewerage, under section 101A of the Water Industry Act 1991.

What is the difference between a drainage field and a watercourse discharge?

A drainage field lets septic tank effluent soak into the soil, where it is treated further; a watercourse discharge sends effluent into a river, stream or ditch. Only treated effluent from a sewage treatment plant may go to surface water.

The surface-water rules add that you can't meet them if you discharge to "a ditch or a surface water that does not contain flowing water throughout the year". A dry ditch is not a compliant outfall.

What are the volume limits?

The limits are 2 cubic metres a day to ground and 5 cubic metres a day to surface water. Go over them and you will need a permit, unless connecting to the sewer is reasonable. Gov.uk confirms both figures on its existing discharges page, which also explains that a discharge stops counting as "existing" if it moves more than 10 metres, changes between ground and surface water, or increases in volume after 2 October 2023.

The limit is about volume, not bedrooms, so the installer sizes the system from British Water's Flows and Loads guidance, which gov.uk says new systems must meet. Adding bedrooms or connecting another property can take you over the limit; gov.uk says you must make sure the system is still big enough if you extend.

When do you need an environmental permit?

You need a permit when you can't meet the general binding rules. Gov.uk lists the usual triggers:

• discharging more than 2 cubic metres a day to ground, or 5 cubic metres a day to surface water;
• a discharge point to ground inside a groundwater source protection zone 1;
• a new discharge from 2 October 2023 within 50 metres of another system discharging under the rules;
• any other rule that applies to you and can't be met.

Gov.uk also makes clear that a permit is not a shortcut: you won't be given one if you could meet the general binding rules.

What extra rules apply to newer systems?

Discharges that started on or after 1 January 2015 face three further tests, set out on the ground rules page:

• Sewer distance. For a single home, you "cannot meet the general binding rules if there's a public foul sewer within 30 metres of any boundary".
• Approvals. You need building regulations approval, and possibly planning permission.
• Protected sites. No discharge in, or within 50 metres of, special areas of conservation, special protection areas, Ramsar sites and certain other protected sites.

For new discharges from 2 October 2023, a system must not share a discharge point with another if the combined volume would exceed the limit, and it needs a permit if it's within 50 metres of another exempt discharge. The full rule set is in the 2023 general binding rules document.

What do the Building Regulations say about septic tanks?

Part H of the Building Regulations 2010 sets the legal requirements, and Approved Document H gives the practical guidance. Requirement H1 puts foul drainage in order of priority: public sewer first, then a private sewer connected to it, then a septic tank with secondary treatment or another treatment system, and a cesspool last.

Requirement H2 says a septic tank and its secondary treatment must be sited and built so that it isn't prejudicial to health, won't contaminate any watercourse or water supply, has adequate access for emptying, and is of adequate capacity, impermeable and ventilated. A durable notice about maintenance must be fixed inside the building.

Approved Document H turns that into numbers:

Which British Standards apply?

Your system must meet the British Standard that applied when it was installed. For current installations, gov.uk names BS EN 12566 for septic tanks and small sewage treatment plants, and BS 6297:2007 for drainage fields. BSI's listing for BS 6297:2007+A1:2008 describes it as the code of practice for the design and installation of drainage fields. Older systems are judged against the standard in force when they went in.

What happens when you sell a house with a septic tank?

You must tell the new operator in writing that a sewage discharge is in place. Gov.uk says the written notice should include:

• a description of the treatment system and drainage system;
• the location of the main parts and the discharge point;
• details of any changes made;
• how the system should be maintained, and the manual if you have one;
• maintenance records, if you have them.

If the septic tank discharges to a watercourse, gov.uk says buyer and seller should agree who will replace or upgrade it "as a condition of sale". Buyers may also want the drains between the house and tank checked; see drain surveys when buying a house.

Septic tank compliance checklist

Use this to check your own system. A "no" or "don't know" means it's worth getting advice.

What are your options if your septic tank doesn't comply?

There are three routes, and the site decides which works:

• Connect to the mains sewer, where one is within reach. The general binding rules then stop applying. See sewer connections.
• Replace the tank with a sewage treatment plant, which can discharge to a flowing watercourse under the rules. See sewage treatment plants.
• Build a new drainage field, if a percolation test shows the ground drains well enough.

Our guide to how a septic tank works explains why the drainage field matters, and septic tank installation cost covers what each route involves.

When to call a professional

Get advice if your septic tank discharges to a ditch or stream, the drainage field is waterlogged or smells, you're selling or buying a property off mains drainage, or you're extending and adding bedrooms. We survey the system, trace where it discharges, and set out plainly which option applies. We install and replace septic tanks, treatment plants and drainage fields, with our groundworks team (from £500 + VAT) handling the excavation, and every job is quoted in writing first.

We don't empty septic tanks. Use a licensed waste carrier, and check them on the gov.uk register of waste carriers. We cover Nottingham and the wider East Midlands; see our areas. Call 07300 600 950 or ask us for a quote.

Sources

• Gov.uk: general binding rules, small sewage discharge to the ground
• Gov.uk: general binding rules, small sewage discharge to a surface water
• Gov.uk: septic tanks and sewage treatment plants, what you need to do
• Gov.uk: general binding rules for small sewage discharges from 2 October 2023
• Legislation.gov.uk: Environmental Permitting (England and Wales) Regulations 2016
• Legislation.gov.uk: Building Regulations 2010, Schedule 1 (Part H)
• Approved Document H: Drainage and waste disposal (gov.uk)
• BSI: BS 6297:2007+A1:2008, design and installation of drainage fields