How to meet the general binding rules if your septic tank or small sewage discharge treatment plant releases (discharges) waste water to a surface water.

Guidance

General binding rules: small sewage discharge to a surface water

How to meet the general binding rules if your septic tank or small sewage discharge treatment plant releases (discharges) waste water to a surface water. From: Environment Agency Published 16 June 2015 Last updated 25 August 2021 — See all updates

Applies to England

Overview

If you’re the operator of a septic tank or small sewage treatment plant, you will not need a permit if you meet all of the general binding rules that apply to you.

The full set of rules are summarised in the policy paper on small sewage discharges in England: general binding rules.

This guide explains which of the general binding rules you must meet if you discharge waste water to a surface water, such as a river, stream, estuary, lake, canal or coastal water.

The rules to meet depend on whether the discharge is ‘existing’ or ‘new’.

You must also have the other permissions that you need to discharge to the environment legally, including:

appropriate building regulations approval
planning permission, where necessary

Existing discharges: what this means

You have an existing discharge if all of these points apply to you:

the discharge was already happening before 1 January 2015
you have not changed the discharge from ground or a different surface water
you have not moved the location of the discharge or, if you have, it is still within 10 metres of the previous location
you have not changed the volume or, if you have, it is not greater than 5 cubic metres (5,000 litres) a day to surface water

If so, check if you can meet the general binding rules for existing discharges. You will not need an environmental permit if you can.

New discharges: what this means

You have a new discharge if you either:

started a discharge from a small sewage treatment plant on or after 1 January 2015
had a discharge to ground before 1 January 2015 which you now want to change to discharge to a surface water, or the other way round
had a discharge to a surface water before 1 January 2015 and you want to discharge more than 10 metres away from the existing one or to a different surface water
had a discharge to a surface water before 1 January 2015 which you now want to increase to more than 5 cubic metres (5,000 litres) a day

If so, check if you can meet all of the general binding rules for existing discharges, plus the additional rules for new discharges. You will not need an environmental permit if you can.

Rules for existing and new discharges

Only discharge 5 cubic metres or less a day in volume (rule 2)

For sewage from a residential property, use the daily discharge calculator to work out how much you discharge a day.

For commercial properties (such as a hotel, restaurant or office) or holiday accommodation (such as a cottage or chalet), use British Water’s Flows and Loads guidance. You will need to add all sources of flow together.

If you discharge more than 5 cubic metres (5,000 litres) a day to surface water you must connect to the public foul sewer when it’s reasonable to do so. You must apply for a permit if it’s not.

Only discharge domestic sewage (rule 3)

The sewage must be domestic in nature, for example from a toilet, bathroom, shower or kitchen of a house, flat or business (such as a pub, hotel or office).

Find out more about what the definition of domestic sewage includes.

Do not cause pollution of surface water or groundwater (rule 4)

The sewage must not cause pollution – find out how to check for pollution.

Use the correct treatment system (rule 6)

You must use a small sewage treatment plant to treat the sewage if you’re discharging to a watercourse such as a river or stream. A sewage treatment plant, also known as a package treatment plant, treats sewage to a higher standard than a septic tank.

If your septic tank discharges directly to a watercourse, as soon as possible you must either:

connect to a public foul sewer
replace your septic tank with a small sewage treatment plant
install a drainage field (also known as an infiltration system) – a series of pipes with holes placed in trenches and arranged so that the waste water can trickle through the ground for further treatment – and check if you meet the general binding rules for discharges to ground

You must have plans in place to do this work within a reasonable timescale, typically 12 months.

If you buy or sell a property with a septic tank that discharges directly into a watercourse

You should agree with the buyer or seller who will be responsible for replacing or upgrading the treatment system. You should agree this as a condition of sale.

New sewer: first time sewerage scheme

If more than one property needs to replace or upgrade their sewerage system, your sewerage undertaker may have a legal duty to provide a sewer for you to connect to. This is known as first time sewerage.

Tidal areas: make sure you discharge below the mean low water spring mark (rule 8)

If you’re in an area where the water level changes according to tides, you must make sure the top end of the pipe that releases sewage is below the ‘mean low water spring mark’. This is the average low water mark at the time of spring tides. Check the low water mark where you live.

Make sure your treatment system meets the right British Standard (rule 9)

Your system must meet the relevant British Standard that was in place at the time it was installed.

The current standards for new systems are:

BS EN 12566 for small sewage treatment plants
BS 6297:2007 for drainage fields

How to check if your treatment system met the British Standard

Your septic tank or treatment plant met the British Standard in place at the time of installation if:

it has a CE mark
the manual or other documentation that came with your tank or treatment plant has a certificate of compliance with a British Standard
it’s on British Water’s list of approved equipment

You can also ask the company that installed your equipment to confirm that it met the British Standard in place at the time of installation.

If your treatment system was installed before 1983 you do not need to do anything to meet the British Standard. There was no British Standard in place before then. You must still meet the other general binding rules that apply to you.

Non-British Standard systems

Retrofit systems within an existing septic tank can only be used if they were installed before 2007. If you have a system like this that was installed after that date, or you are planning on installing one of these systems, you must apply for an environmental permit.

You can only use a reedbed or a secondary treatment unit, installed after a septic tank, to discharge to a watercourse if it meets the relevant British Standard. Otherwise you must either:

upgrade to a sewage treatment plant
apply for a permit so the Environment Agency can assess the risk of using this sort of system in your location

Make sure your treatment system is installed and operated correctly and has enough capacity (rule 10)

Your treatment system must be large enough to handle the maximum amount of sewage it will need to treat.

If you install a new small sewage treatment plant you must check with the installer that it meets the sizing requirements in British Water’s Flows and Loads guidance.

Your treatment system must be installed and operated in line with the manufacturer’s specification. This is the instruction manual or technical set of requirements that comes with the equipment.

If the amount of sewage the system needs to treat increases

You must make sure the treatment system is still big enough. For example, this could be if you extend your property or connect another property. You must recalculate the maximum daily volume of your discharge.

If you discharge more than 5 cubic metres (5,000 litres) a day to surface water you must connect to the public foul sewer when it’s reasonable to do so. You must apply for a permit if it’s not.

Get your treatment system regularly maintained (rule 11)

You should have your treatment system regularly maintained in line with the manufacturer’s instructions. If these are not available, ask your local maintenance company for advice.

You must have your treatment system repaired or replaced if it is not in good working order. For example, this could be if it has:

leaks
cracks in tank walls or pipes
blocked pipes
signs that the waste water is not draining properly, like pools of water around the drainage point
sewage smells
a failed motor
a failed pump
a failed electrical supply

Anyone who carries out maintenance on your system must be competent (rule 11). Competent people include those on British Water’s list of accredited service engineers.

If you change your treatment system, check if it’s now classed as a new discharge.

Get your treatment system regularly emptied (rule 12)

You must get the sludge that builds up in your sewage treatment plant removed (desludged) before it exceeds the maximum capacity. As a minimum, you should have your treatment system desludged once a year or in line with the manufacturer’s instructions.

The company you use to dispose of your waste sludge must be a registered waste carrier. You can find this out by either asking the:

company to confirm this when you arrange to have your tank emptied
tanker driver for a copy of the company’s waste carrier’s certificate

You sell your property: tell the new owner about the sewage treatment system (rule 13)

If you sell your property, you must tell the new operator (the owner or person responsible for the sewage treatment plant) in writing that a sewage discharge is in place.

Include:

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

You stop using your treatment system: make sure it’s decommissioned properly (rule 14)

You must remove anything that could cause pollution (for example, remaining sludge) when you stop using a septic tank or sewage treatment plant.

This does not apply if you only stop using the equipment temporarily, for example if your property is empty.

You can ask a maintenance company for advice on how to decommission your septic tank or treatment plant properly.

New discharges: additional rules

Check if you can connect to a nearby public foul sewer (rule 15)

If you connect to a public foul sewer:

the general binding rules will not apply to you
you will not need a permit

To find out if there is a public sewer near your property, contact your local water company.

For a single domestic property

You cannot meet the general binding rules if there’s a public foul sewer within 30 metres of any boundary of the premises that your system serves.

If you’re building a development of more than one property

Multiply the number of houses by 30 metres.

Example If there are 3 properties then this will give you a distance of 90 metres (3 × 30 metres).

You cannot meet the general binding rules if any boundary of the premises that your system serves is within that distance of a public foul sewer.

If some or all of your discharge is from non-domestic properties

Divide the maximum volume in cubic metres that you want to discharge from those other premises by 0.75 (1 cubic metre is 1,000 litres). Multiply the result by 30. This will give you a result in metres.

Example A discharge of 1.2 cubic metres divided by 0.75 gives 1.6, which multiplied by 30 gives a result of 48 metres.

You should cannot meet the general binding rules if any boundary of the premises that your system services is within that distance of a public foul sewer.

If your discharge is in a sewered area

Check what you need to do if your discharge is in a sewered area.

If there is no public foul sewer, check if your sewerage undertaker has a duty to provide first time sewerage.

Make sure the discharge point is not in or near protected sites (rule 17)

You cannot meet the general binding rules if the new discharge will be in or within 500 metres of any:

biological sites of special scientific interest (SSSI)
special protection areas
special areas of conservation
Ramsar wetland sites
designated bathing water
protected shellfish water
freshwater pearl mussel population

You also cannot meet the rules if the new discharge will be in or within:

200 metres of an aquatic local nature reserve
50 metres of a chalk river or aquatic local wildlife site

If you have or are planning to start a new discharge to ground in or near a protected site, you must connect to the public foul sewer when it’s reasonable to do so. You must apply for a permit if it’s not.

How to check the locations of protected sites

You can use Magic map to identify the locations of most of these sites.

Search for the discharge site location.
In the table of contents, open ‘Designations’, then ‘Land-Based Designations’, then ‘Statutory’. Select ‘Sites of Special Scientific Interest (England)’, ‘Special Protection Areas (England)’, ‘Special Areas of Conservation (England)’, ‘Ramsar Sites (England)’ and ‘Local Nature Reserves (England)’
If the discharge will be to an estuary or the sea you should also open ‘Marine Designations’, then ‘Statutory’. Select ‘Special Protection Area (Marine) (GB)’, ‘Special Area of Conservation (Inshore) (GB)’, ‘Special Area of Conservation (Offshore) (GB)’ and ‘Bathing Waters 2016 (England)’. Also open ‘Marine’ in the table of contents, then ‘Fisheries and Fishing Activity’. Select ‘Shellfish Waters 2014 (England)’.
To measure the distance from the discharge site to any protected sites, select the ‘Measure’ tool from the menu then use the ‘Distance’ option.
To find out if a site is a biological SSSI or if a local nature reserve is aquatic, select the ‘Identify’ tool from the menu, then select the protected site on the map. Open the site detail link to read the description.

Magic does not indicate the locations of freshwater pearl mussel populations, chalk rivers or aquatic local wildlife sites.

If you don’t know whether the discharge will be in or near a protected site, or if you cannot use Magic, contact the Environment Agency to request a nature and heritage conservation screening.

Make sure the surface water has flow (rule 19)

You cannot meet the general binding rules if you have a new discharge to:

a ditch or a surface water that does not contain flowing water throughout the year, unless there is a drought or an unusually long period of dry weather
watercourses that seasonally dry up

Do not discharge to an enclosed lake or pond (rule 21)

You cannot meet the general binding rules if you have a new discharge to an enclosed lake or pond. This means a lake or pond in which all of the following apply:

it contains water throughout the year, other than in extreme weather conditions
it does not have an outfall that connects it to a watercourse, or has an outfall that only discharges in extreme weather conditions
it is sealed or lined to prevent water draining into the ground or soaking into the surrounding soil

You do not need a permit to discharge to an enclosed lake or pond. But you must use appropriate pollution prevention measures to make sure your discharge does not cause pollution.

Make sure any partial drainage field is close enough to the watercourse (rule 20)

A partial drainage field is a length of perforated pipe that is installed between the sewage treatment plant and the outfall. It is installed instead of a solid pipe. This allows some of the waste water to soak into the ground when the ground is dry and flows in the watercourse are likely to be lower.

If you’re using a partial drainage field for a new discharge, the perforated section of the pipe must not extend more than 10 metres from the edge of the watercourse. You must only use it with a small sewage treatment plant, not a septic tank.

More information on the rules

You should get advice from a competent service engineer if you need help understanding:

what treatment system you have
what you are required to do under the general binding rules

British Water provides a list of accredited service engineers. There may be other competent service engineers.

There’s also guidance on how to meet the general binding rules if your septic tank or small sewage treatment plant discharges to the ground.

If you cannot meet all of the rules that apply to you

You must either:

connect to a public foul sewer – contact your sewerage undertaker for advice
change your treatment system so that it can meet the general binding rules

If you cannot change your system and it’s not reasonable to connect to a public foul sewer, then you must apply for a permit. In your application you must justify why it’s not reasonable to connect to a public foul sewer. The Environment Agency will then assess the risk of using your system at your location.

Enforcement

If your discharge causes pollution you may be committing an offence. The Environment Agency will give you advice to help you fix the problem. If your discharge continues to cause pollution the Environment Agency may take enforcement action against you.

Published 16 June 2015
Last updated 25 August 2021