Septic tank regulations

Three regulators, three systems, and one set of Building Regulations across England and Wales (Scotland has its own building standards). This page sets out what each asks of a septic tank or small sewage treatment plant, in the regulators' own terms, with links to the source. Read November 2026; general guidance, not legal advice.

The three nations side by side

From GOV.UK, SEPA and NRW guidance, read November 2026. Northern Ireland has separate rules under its own regulator.
Rule	England	Scotland	Wales
Regulator	Environment Agency	SEPA	Natural Resources Wales
Small systems	General binding rules; no registration if you comply	Registration under EASR (CAR until 31 Oct 2025)	Exemption registration
Fee	None under the rules; permits are charged	£198.55 for a new registration	Free
Limit to ground	2 m³ (2,000 litres) a day	Up to 10 homes or 50 population equivalent	Under 2,000 litres a day
Limit to water	5 m³ (5,000 litres) a day	Up to 10 homes or 50 population equivalent	Under 5,000 litres a day
Septic tank to a watercourse	Not allowed: replace or upgrade	Only as SEPA authorises	Not allowed: package treatment plant needed
Public sewer nearby	Within 30 m of the boundary: connect (since 2015)	Connect where possible	Must be at least 30 m from a public foul sewer
Groundwater	Permit needed in Source Protection Zone 1	Assessed at registration	Not in SPZ1 or within 50 m of a drinking water source

England: the general binding rules

Since 2015 small sewage discharges in England have been regulated by general binding rules rather than individual permits. If you meet every rule that applies to you, you need no permit and there is nothing to register. Which rules apply depends on when the discharge started: before 2015, between 1 January 2015 and 1 October 2023, or from 2 October 2023, with more conditions for each later date.

Rules for every discharge

Volume: no more than 2 m³ a day to ground or 5 m³ a day to surface water. A normal house is well below either.
Domestic sewage only, from toilets, bathrooms, showers and kitchens, and it must not cause pollution.
The right system for the outlet: a septic tank or treatment plant followed by a drainage field for ground; a small sewage treatment plant for surface water. A septic tank discharging directly to a watercourse has to be replaced or upgraded.
British Standards: BS EN 12566 for tanks and plants and BS 6297:2007 for drainage fields, as in force when installed. Systems from before 1983 are exempt from this one rule.
No newer soakaway pits: soakaways, wells and boreholes installed after December 2007 do not meet the ground rules.
Sized, installed and maintained properly, resized if the load increases, maintained by a competent person, and emptied before it is full and at least once a year by a registered waste carrier.
On sale: hand the new owner written details of the system and its maintenance.

Extra rules for discharges started since 2015

Not allowed if a public foul sewer is within 30 metres of the boundary of a single home (30 metres per house for developments).
Not allowed in or near protected sites: within 500 metres of SSSIs, special areas of conservation, special protection areas, Ramsar sites, bathing and shellfish waters and pearl mussel populations for surface water, or within 50 metres of a chalk river; within 50 metres of SSSIs and other designated sites, or in ancient woodland, for ground.
Surface water discharges must go to a watercourse that flows all year.
Building Regulations approval is required for a new system.

Extra rules for discharges started since 2 October 2023

A new discharge must not share an outlet if the combined flow would exceed the limit, and needs a permit if it is within 50 metres of another system already discharging under the rules. Ask your neighbours where theirs is.

Groundwater Source Protection Zone 1

A discharge to ground in SPZ1, or within 50 metres of a private drinking water supply, needs a permit. Check on the Magic map or ask the Environment Agency for a screening.

Sources: discharges to the ground (updated 23 July 2026) and discharges to surface water, GOV.UK.

Scotland: SEPA authorisation

Scotland does not use the general binding rules. Any discharge from a septic tank or private sewage treatment system needs authorisation from SEPA. On 1 November 2025 the Controlled Activities Regulations (CAR) were replaced by the Environmental Authorisations (Scotland) Regulations (EASR). Registrations held on 31 October 2025 carried over automatically, and from 1 March 2026 they are subject to standard conditions: treat the sewage to the level previously authorised, maintain the system and outfall, and cause no significant impact on drinking water or the water environment.

A new registration covers up to 10 homes, or up to 50 population equivalent, discharging to land (via a soakaway, categorised by soil percolation value) or to water. It costs £198.55. Discharges to a freshwater loch or a phosphate sensitive catchment need a permit instead. New discharges should connect to the public sewer where possible.

Upgrading from a septic tank to a treatment plant, or a like-for-like replacement, needs no new application. Moving the outfall more than 10 metres or switching from land to water does. In Scotland a building warrant from the council is also needed for a new system.

Sources: SEPA septic tanks and private sewage, existing CAR registrations, making a change.

Wales: register with NRW

Natural Resources Wales asks owners of septic tanks and package treatment plants to register them, and in most cases this is a one-off, free registration. To qualify, the system must take domestic sewage only, discharge less than 2,000 litres a day to a drainage field or less than 5,000 litres a day to a watercourse, be at least 30 metres from a public foul sewer (multiplied by the number of properties), and be clear of sensitive sites.

Discharges to ground must not be in Source Protection Zone 1 or within 50 metres of a well, spring or borehole used for drinking water. Any discharge to surface water must come from a package treatment plant, and that applies to systems in use before 6 April 2010 too. If a system cannot be registered, a permit is needed.

Source: NRW: register your septic tank or small sewage treatment plant.

Not sure your system meets the rules where you live? An installer can survey it and tell you what has to change.

Ask for a site visit

Building Regulations Part H

In England and Wales, a new septic tank, treatment plant or cesspool needs Building Regulations approval under Part H, and that includes a replacement. Approved Document H2 is the guidance building control will judge it against. The main points:

Tank size: at least 2,700 litres for up to four people, plus 180 litres for each extra person.
Siting: council guidance on Part H puts the tank at least 7 metres from the habitable part of any building and within 30 metres of access for the emptying tanker.
Drainage field: at least 15 metres from any building and 10 metres from any watercourse, sized from a percolation test.
Percolation test: holes 300 mm square dug 300 mm below the proposed pipe level, timed as water falls 150 mm, repeated and averaged to give Vp.
Field area: people × Vp × 0.25 m² after a septic tank, or × 0.2 after a treatment plant.
Cesspools: at least 18,000 litres for two people, plus 6,800 litres for each extra person, with no outlet.

Sources: GOV.UK: Approved Document H; Lancaster City Council: Part H guidance leaflet.

Planning permission

Planning is separate from both Building Regulations and the discharge rules. A like-for-like replacement often does not need it, but a new outlet, a plant kiosk, work in a national park or near a listed building might. Ask your local planning authority before you dig.

Northern Ireland

Northern Ireland has its own discharge consent system and building regulations. This site's rule summaries cover England, Scotland and Wales.

See what the work costs

Questions about the regulations

What are the septic tank regulations in England?

The Environment Agency's general binding rules for small sewage discharges. If you meet them you need no permit or registration. They cover volume, domestic sewage only, no pollution, the right kind of system for the outlet, British Standards, sizing, maintenance, yearly emptying, sale and decommissioning. GOV.UK.

What were the 2020 septic tank regulations?

There was no separate 2020 law. The general binding rules, introduced in 2015, say a septic tank must not discharge directly to surface water. Guidance updated in 2018 said that where a property with such a tank was sold before 1 January 2020, buyer and seller should settle who replaces it as a condition of sale. Owners of these tanks must replace or upgrade them.

Do I have to register my septic tank?

In England, no, if it meets the general binding rules. In Wales, yes: registration with NRW is free and usually one-off. In Scotland, yes: a SEPA authorisation is needed, and a new registration costs £198.55.

What happens if my septic tank does not meet the rules?

You must fix it: connect to the sewer, change the system so it complies, or apply for a permit. The regulators advise first, but causing pollution can be an offence and enforcement action can follow if it continues.

What must I give the buyer when I sell a house with a septic tank?

In England, written details of the system: what it is, where its parts and the drainage are, changes made, maintenance requirements and manual, and maintenance records. If the tank discharges to a watercourse, agree in writing who will replace it.

Do I need Building Regulations approval for a septic tank?

Yes, for a new septic tank or treatment plant, including a replacement. Approved Document H sets out how to size the tank and drainage field and where they can go. Planning permission may also be needed.

How often must a septic tank be emptied?

In England the rules say before it reaches capacity and at least once a year, unless the manufacturer says otherwise, using a registered waste carrier. SEPA also expects annual de-sludging.

Keep reading

Septic tank replacement
When an old tank has to go.
Sewage treatment plant installation
The system for a watercourse outlet.
Drainage field installation
Percolation tests and sizing.
Septic tank survey
Checks for buyers and sellers.

Ask for a site visit and prices

Three short steps: where the property is, what the system needs, and how to reach you. About two minutes.

A free matching service, not a off-mains drainage installer. We look for one who works in your area and name them to you first. Nothing is shared until you say yes.

Step 1 of 3

Where is the property?

Postcode