The general binding rules you must meet depend on when your discharge to ground started.
You’re in this category if all these points apply:
If you have replaced your treatment system but all these points apply, you’re still in this category.
If so, you must meet the ’rules that apply to all discharges’. (Not the additional rules.)
You’re in this category if, on or after 1 January 2015 but before 2 October 2023, you:
If so, you must meet the:
You’re in this category if, on or after the 2 October 2023, you:
If so, you must meet the:
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 2 cubic metres (2,000 litres) a day to ground 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.
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.
The sewage must not cause pollution – find out how to check for pollution.
You must use a septic tank or a small sewage treatment plant to treat the sewage and then discharge the waste water to ground through a drainage field. You must not discharge effluent from a septic tank to a watercourse.
A septic tank is an underground tank where the solids sink to the bottom, forming a sludge, and the waste water flows out to a drainage field.
A small sewage treatment plant, also known as a package treatment plant, works in a similar way to a septic tank. But it uses mechanical parts to treat the waste water to a higher standard before it goes to a drainage field.
A drainage field, also known as an infiltration system, is a series of pipes with holes placed in trenches. These are arranged so that the waste water can trickle through the ground for further treatment.
The system you use must meet the relevant British Standard (see rule 9).
Discharges through drainage mounds can meet the general binding rules if:
You cannot meet the general binding rules if you’re using:
Instead you must either:
You should avoid using non-standard systems such as boreholes, shafts, concrete rings or similar structures for new discharges to ground. These are not usually appropriate ways of disposing of sewage effluent because of their increased risk of pollution.
If your sewage effluent discharges directly to groundwater (at any time of year) through any of these non-standard systems:
This is explained in section G of the Environment Agency’s approach to groundwater protection.
To prevent groundwater pollution you must check if the discharge point is in a groundwater source protection zone 1(SPZ1).
A groundwater SPZ1 can be the area around a commercial water supply used for drinking water or food production. To check if your discharge is in the inner zone (zone 1) you can either:
A groundwater SPZ1 can also be any area within 50 metres of a private water supply for human consumption. Ask your neighbours if they have one and, if so, how far their spring, well or borehole is from your drainage field.
If the discharge point is in a SPZ1 (except SPZ1c) you must apply for a permit. A permit will include additional conditions to the general binding rules.
The Environment Agency will grant the permit if either:
If there’s evidence of pollution or the risk of pollution is unacceptable, the Environment Agency will ask you to make changes to your system. They will either refuse to grant a permit or issue a permit with improvement conditions.
The Environment Agency regularly checks:
If the Environment Agency finds your system may be causing pollution to surface or groundwater they will contact you to discuss the issues. This may result in them reviewing or revoking your permit. Follow the guidance on how to comply with your permit.
Your system must meet the relevant British Standard that was in place at the time it was installed.
If different parts of your treatment system were installed at different times, each part must meet the relevant British Standard in place at the time of installation.
The current standards for new systems are:
Your septic tank or treatment plant met the British Standard in place at the time of installation if:
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.
Your treatment system must be large enough to handle the maximum amount of sewage it will need to treat.
If you install a new septic tank, small sewage treatment plant or drainage field (or installed one after 1 February 2006) 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.
You must make sure the treatment system is still big enough. For example, this could be if you extend your property or connect to an another property. You must recalculate the maximum daily volume of your discharge.
If you discharge more than 2 cubic metres (2,000 litres) a day to ground 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.
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:
Anyone who carries out maintenance on your system must be competent. 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. To do this, see the section ‘Work out which rules apply to you’.
You must get the sludge that builds up in your septic tank or sewage treatment plant removed (desludged) before it goes beyond the maximum capacity. You should do this at least once a year or in line with the manufacturer’s instructions.
If you do not desludge your tank often enough, solids from the tank are likely to be carried into the drainage field or soakaway. This can cause damage and pollution, leading to potentially expensive and disruptive repairs.
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:
If you sell your property, you must tell the new operator (the owner or person responsible for the septic tank or small sewage treatment plant) in writing that a sewage discharge is in place.
Include:
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.
If you connect to a public foul sewer:
To find out if there is a public foul sewer near your property, contact your local water company. Owners of neighbouring properties will also be able to tell you if their property is connected to a public sewer.
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.
Multiply the number of houses by 30 metres.
ExampleIf 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.
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.
ExampleA discharge of 1.2 cubic metres divided by 0.75 gives 1.6, which multiplied by 30 gives a result of 48 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.
Check what you need to do if your discharge is in a sewered area.
If there’s no public foul sewer and a discharge can negatively affect the property or environment, check if your sewerage undertaker has a duty to to build and pay for a new sewer for you to connect to. This is known as first time sewerage.
You must have building regulations approvalif you have or are planning to install a new septic tank or small sewage treatment plant. You may also need planning permission.
A new discharge must not use the same outlet as any other discharge if the combined volume is greater than 2 cubic metres (2,000 litres) a day to ground. You must have a permit for the new discharge if the combined volume of the new and existing discharges is above this limit.
Ask your neighbours if their foul drainage solution discharges under the general binding rules. If so, ask how far their discharge is from your discharge location.
You must have a permit for the new discharge if it’s within 50 metres of any other system that discharges under the general binding rules.
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