CLEARMASTERS
The short version
What are the septic tank rules?
If you have a septic tank or sewage treatment plant in England, you must follow the Environment Agency’s general binding rules, or get a permit. In short: septic tanks must drain to a drainage field, never to a stream; only treatment plants can discharge to a watercourse; stay under 2 cubic metres a day to ground or 5 to water; get it emptied at least once a year; keep it maintained; don’t cause pollution; and tell the buyer in writing when you sell.
Who’s responsible?
The rules apply to the operator: usually the owner, but it can be the person who uses the system, even if it’s on a neighbour’s land, or a tenant with a written agreement. If a system is shared, everyone who uses it is responsible.
Meet the rules, no permit needed
If your system meets every rule that applies to it, you don’t need a permit or to register it in England. If it can’t, you must connect to the sewer, change the system, or apply to the Environment Agency for a permit.
Compliance checker
Does my septic tank comply?
Answer up to seven questions and get a plain-English report: what needs action, what’s worth checking and what looks fine.
Rules explorer
Which general binding rules apply to me?
The rules depend on where your system discharges and when the discharge started. Choose yours to see the list.
11 rules apply to your system
- Any start date
Stay within the daily volume limit
No more than 2 cubic metres (2,000 litres) a day to the ground, or 5 cubic metres a day to a watercourse. For homes, the Environment Agency has a daily discharge calculator.
- Any start date
Only discharge domestic sewage
Waste from toilets, bathrooms, showers and kitchens. That includes businesses such as pubs and offices, but not trade or industrial waste.
- Any start date
Don’t cause pollution
The discharge must not pollute surface water or groundwater. Smells, sewage on the surface or a dirty outlet are warning signs.
- Any start dateTo ground
Use the right treatment system
A septic tank must discharge to a drainage field, never to a watercourse. Wells, boreholes and rainwater soakaways installed after December 2007 don’t qualify.
- Any start dateTo watercourse
Use a treatment plant for a watercourse
Only a small sewage treatment plant may discharge to a stream or river. A septic tank discharging to a watercourse must be replaced, moved to a drainage field or connected to the sewer.
- Any start dateTo ground
Not in a source protection zone 1
Ground discharges can’t be in groundwater source protection zone 1, which includes anywhere within 50 metres of a private drinking water supply such as a well or spring.
- Any start dateTo watercourse
Tidal waters: below low water
If you discharge into tidal waters, the outlet must be below the mean low water spring mark.
- Any start date
Meet the British Standard
The system must meet the British Standard in force when it was installed. Systems installed before 1983 are exempt from this one rule, but not the others.
- Any start date
Installed correctly, with enough capacity
Installed and run to the manufacturer’s specification, and big enough for the maximum load. If you extend the house or add a connection, the volume must be recalculated.
- Any start date
Keep it maintained
Maintained by a competent person, and repaired or replaced if it leaks, cracks, blocks, smells or its motor, pump or power fails.
- Any start date
Get it emptied regularly
Sludge removed before it reaches the tank’s capacity, at least once a year or as the manufacturer says, by a registered waste carrier.
- Any start date
Tell the buyer when you sell
Give the new owner written details: what the system is, where it is, any changes made and its maintenance records.
- Any start date
Decommission it properly
If you stop using the system for good, remove anything that could cause pollution, such as remaining sludge.
- Started since 2015
Connect to the sewer if it’s close
You can’t use the rules if a public foul sewer is within 30 metres of your property boundary (for a development, 30 metres for each house).
- Started since 2015
Get building regulations and planning approval
A new septic tank or treatment plant needs building regulations approval, and may need planning permission.
- Started since 2015To ground
Keep away from protected sites (ground)
Not in ancient woodland, or within 50 metres of a special area of conservation, special protection area, Ramsar site or biological SSSI.
- Started since 2015To watercourse
Keep away from protected sites (watercourse)
Not within 500 metres of an SSSI, special protection area, special area of conservation, Ramsar site, bathing water or protected shellfish water, 200 metres of an aquatic local nature reserve, or 50 metres of a chalk river.
- Started since 2015To watercourse
The watercourse must flow all year
You can’t discharge to a ditch or stream that dries up for part of the year, except in a drought.
- Started since 2015To watercourse
Partial drainage fields: within 10 metres
A partial drainage field next to a watercourse can only serve a treatment plant, and the perforated pipe can’t extend more than 10 metres from the bank.
- Started since 2015To watercourse
No enclosed lakes or ponds
The rules can’t be used to discharge into an enclosed lake or pond.
- Started since Oct 2023
Don’t share a discharge point over the limit
A new discharge can’t share an outlet with another if their combined volume would go over the limit.
- Started since Oct 2023
Not within 50 metres of another system
A new discharge needs a permit if another system using the general binding rules discharges within 50 metres.
Summarised from the GOV.UK general binding rules guidance. A discharge counts as “started” again if it’s moved more than 10 metres, switched between ground and watercourse, or increased beyond the limits.
The big one
Septic tanks that discharge to a stream or ditch
The rule that catches most people out is simple: a septic tank must not discharge directly to a watercourse. Septic tank effluent is only partly treated, and it needs the soil in a drainage field to finish the job.
If yours does, you must do one of three things as soon as possible, and the Environment Agency usually expects plans within 12 months:
- Replace it with a sewage treatment plant, which can discharge to a watercourse
- Install a drainage field so it discharges to the ground instead
- Connect to the mains sewer, if one is close enough
A septic tank conversion unit can sometimes upgrade an existing tank, but it needs a permit and evidence that it treats to the same standard as a treatment plant.
Timeline
How the septic tank rules came about
- 1983
First British Standard
Systems installed before 1983 don’t have to meet a British Standard, but must meet every other rule.
- 2007
Soakaways tightened
Rainwater soakaways installed after December 2007 don’t count as drainage fields for sewage.
- 2015
General binding rules
The rules started on 1 January 2015, with extra conditions for discharges started from that date.
- 2020
Septic tanks to streams
The original deadline to replace or upgrade septic tanks discharging to a watercourse was 1 January 2020.
- 2023
Rules updated
From 2 October 2023, new discharges can’t share an outlet over the limit or be within 50 metres of another system.
If you can’t meet the rules
When do you need a septic tank permit?
You’ll need a permit if…
- You discharge more than 2 m³ a day to ground or 5 m³ a day to a watercourse
- Your ground discharge is in a source protection zone 1
- You’re in or close to a protected site
- A new discharge is within 50 metres of another system using the rules
- You can’t meet any other rule that applies, and can’t connect to the sewer
Applying
Permits come from the Environment Agency. Your application must explain why connecting to the public sewer isn’t reasonable, and the Agency will look at the risk at your site before deciding.
Often the simpler answer is to change the system so it does meet the rules: for example, replacing a septic tank with a treatment plant, or a soakaway with a proper drainage field.
How much is too much?
The 2 m³ and 5 m³ volume limits
Under the rules you can discharge up to 2 cubic metres (2,000 litres) a day to the ground, or 5 cubic metres a day to a watercourse. A typical single home is comfortably under both.
It’s larger properties that need care: several homes sharing one system, big houses, barn conversions, holiday lets, B&Bs, pubs and offices. For homes, the Environment Agency’s daily discharge calculator works out the figure; businesses use British Water’s Flows and Loads guidance.
If you extend the house or add connections, the volume has to be recalculated, and the system may need upgrading to cope.
Different rules
What about cesspits?
No discharge, no general binding rules
A cesspit is a sealed tank with no outlet, so the general binding rules don’t apply and you don’t need a permit, unless the Environment Agency tells you otherwise.
You must keep it in good condition, make sure it doesn’t leak or overflow, and get it emptied regularly by a registered waste carrier.
When a cesspit isn’t a cesspit
If liquid leaves the tank, or it hardly ever needs emptying, it’s either a septic tank or a cesspit that’s leaking. A leaking cesspit is pollution, and the Environment Agency or your council can make you repair or replace it.
Not sure which you have? See our guide to septic tanks, cesspits and treatment plants.
Outside England
Septic tank rules in Wales and Scotland
Wales
Septic tanks and small sewage treatment plants are regulated by Natural Resources Wales. Most systems must be registered with NRW, and the rules differ from England’s.
Scotland
In Scotland, systems are regulated by SEPA and must be registered. If you sell, the registration should be updated for the new owner.
We work across Surrey, Sussex, Kent, Hampshire and London, where the English rules apply. This guide is general information, not legal advice.
How we can help
Not sure if yours meets the rules?
We check septic tanks and treatment plants against the general binding rules every week, for homeowners, buyers, sellers and landlords. We’ll tell you plainly where you stand and what, if anything, needs doing.
Call 03333 233566Septic tank surveys
A full check of the tank, the outlet and the drainage field.
Treatment plant upgrades
Replacing a septic tank that discharges to a watercourse.
Drainage fields
New and replacement drainage fields, tested and designed to the rules.
Yearly emptying
With a waste transfer note every time, for your records.
Questions answered
Septic tank regulation FAQs
What are the general binding rules for septic tanks?
They are the conditions set by the Environment Agency that let you run a septic tank or small sewage treatment plant in England without an environmental permit. They cover how much you discharge, where it goes, the type of system, maintenance and emptying, what you tell a buyer, and extra rules for systems installed since 2015 and since October 2023.
Is it illegal for a septic tank to discharge into a stream?
Under the general binding rules, a septic tank must not discharge directly to a watercourse. If yours does, you must replace it with a treatment plant, move the discharge to a drainage field, or connect to the mains sewer as soon as possible. The Environment Agency usually expects plans to be in place within 12 months.
Do I need a permit for my septic tank?
Not if your system meets all the general binding rules that apply to it. You need a permit if you cannot meet them, for example if you discharge more than 2 cubic metres a day to the ground or 5 to a watercourse, discharge in a source protection zone 1, or are too close to a protected site. Your application has to explain why connecting to the sewer is not reasonable.
How often must a septic tank be emptied by law?
The rules say the sludge must be removed before it reaches the tank’s capacity, at least once a year or as often as the manufacturer recommends, by a registered waste carrier.
What happened to the 2020 septic tank deadline?
When the rules were introduced, septic tanks discharging to a watercourse had to be replaced or upgraded by 1 January 2020, or sooner if the property was sold. That date has passed, so any septic tank still discharging to a watercourse should be dealt with as soon as possible, and it often comes to light when a house is sold.
Does my old septic tank have to meet the British Standard?
Systems installed before 1983 do not have to meet a British Standard, because there was none at the time. They still have to meet all the other rules, including not causing pollution and not discharging to a watercourse if they are septic tanks.
Do the rules apply in Wales and Scotland?
No. The general binding rules on this page apply in England. In Wales, septic tanks and treatment plants are registered with Natural Resources Wales, and in Scotland with SEPA, under their own rules.
What happens if my septic tank causes pollution?
Causing pollution may be an offence. The Environment Agency will usually give advice first, but can take enforcement action if the pollution continues. The rules also require you to repair or replace a system that is not in good working order.
Got a different question? Call 03333 233566 or send us a message.