Statutory guidance

SR2025 No 7: guidance – domestic sewage effluent with a maximum daily volume of 5 cubic metres per day to surface water using non-British Standard equipment or where the watercourse does not always have flow, or both

Published 20 April 2026

Applies to England

1. Check if your discharge is domestic sewage

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.

2. Check the volume of your discharge

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.

3. Use the correct treatment system and obtain evidence that it is capable of consistently treating the effluent to the required standards

The sewage effluent must be secondary treated. This usually means using a British Standard small sewage treatment plant, also known as a package treatment plant, which treats the waste water using mechanical parts before it is discharged.

The standard rules permit allows secondary treatment to be delivered using works and equipment that does not conform to the British Standard, for example equipment that is retrofitted to an existing septic tank. 

Small sewage treatment plants that are certified under the British Standard have been through a testing process to ensure that they deliver a good standard of secondary treatment. Any equipment which is not British Standard certified will not have been subject to the same testing process, either because the testing is not available or because the manufacturer has chosen not to have the testing done.

If you will be treating the effluent using equipment which is not British Standard certified, you should ask the manufacturer or installer to provide written evidence that the sewage treatment system they create for you will comply with the requirements of the permit. You should keep this evidence with your management system documents.

The standard rules permit requires that the sewage treatment plant is designed, operated and maintained so as to ensure that any effluent discharged does not exceed specified standards. If the discharge does not consistently meet the standards, then it may cause pollution and the operator of the discharge could be prosecuted.

The addition of equipment to existing septic tanks that are in poor condition will not create a sewage treatment system that consistently treats effluent effectively and is likely to lead to the system failing to comply with the conditions of the standard rules permit.

4. If you are using works and equipment that are not British Standard, make sure your new discharge will be replacing an existing discharge

If the effluent will be treated using works and equipment that are not British Standard, then the standard rules permit can only be used if the discharge is existing. You cannot use this standard rules permit to start a new discharge to surface water using works or equipment that are not British Standard. An existing discharge means a discharge that was in place and discharging directly to the same watercourse before 2 October 2023.

5. Check your treatment system meets the relevant British Standard

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:

• BS EN 12566 for small sewage treatment plants
• BS:2007+A1:2008 for drainage fields

6. Check if your treatment plant met the British Standard

If you use a small sewage treatment plant, then it 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 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 plant 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. However, it is unlikely that a treatment system installed before this date would be compliant with the conditions of the standard rules permit.

7. Create a management system

The standard rules permit requires the activity to be operated and managed in accordance with a written management system. See guidance on how to create a management system.

8. In tidal areas, make sure you discharge below the mean low water spring mark

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.

9. If you will be discharging to a watercourse that does not always have flow then make sure the discharge is not in a groundwater source protection zone 1 or within 125 metres of a well, spring or borehole that is used to supply water for domestic or food production purposes

The standard rules permit requires that effluent is discharged to ground via a perforated pipe when the receiving watercourse does not have flow. 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:

• use Magic map – search for the discharge location, then select ‘Source Protection Zones merged (England)’ from the non-statutory land-based designations in the table of contents
• contact the Environment Agency to request a nature and heritage conservation screening if you cannot use Magic map

The discharge may also not be within 125 metres of a well, spring or borehole that is used to supply water for domestic or food production purposes. Local authorities will keep records of private water supplies as part of their duties under The Private Water Supplies (England) Regulations 2016 and a request could be made for information on the presence of supplies within a 125 metre radius of the proposed discharge. You could also ask your neighbours if they have a private water supply and, if so, how far their spring, well or borehole is from your drainage field.

10. Check if you can connect to a nearby public foul sewer

If you connect to a public foul sewer you will not need an environmental permit.

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.

When we determine applications for standard rules permits we cannot review any information concerning whether a connection to the public foul sewer is possible, for example due to obstacles between a property and the sewer pipe. Therefore, if a sewer is shown as being present within the distances specified below, you will not be able to apply for the standard rules permit and will instead need to apply for a bespoke permit.

10.1 For a single domestic property

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

If the system serves 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 conditions of the standard rules permit if any boundary of the premises that your system serves is within that distance of a public foul sewer.

10.2 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 cannot meet the conditions of the standard rules permit if any boundary of the premises that your system serves is within that distance of a public foul sewer.

10.3 If your discharge is from both domestic and non-domestic properties

Where the discharge is from both domestic and non-domestic properties, the 2 distances should be added together.

Example

A discharge serves 3 domestic properties, giving a distance of 90 metres. It also serves a café discharging 1.2 cubic metres per day, giving a distance of 48 metres. These distances should be added together, giving a total distance of 138 metres.

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

10.4 If your discharge is in a sewered area

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 build and pay for a new sewer for you to connect to. This is known as first time sewerage.

11. Check the discharge point is not in or near protected sites

You cannot use the standard rules permit if the discharge will be made to surface water within 500 metres upstream of any:

• European Site – these are Special Areas of Conservation (SAC) and Special Protection Areas (SPA), or potential Special Protection Areas, proposed Special Areas of Conservation, listed or proposed Ramsar sites, and areas secured as sites compensating for damage to a European site
• biological sites of special scientific interest (SSSI)
• Ramsar site
• designated bathing water
• Marine Conservation Zone
• protected shellfish water
• freshwater pearl mussel population
• any body of water identified as containing a Protected Species

You also cannot use the standard rules permit if the discharge will be in or within:

• 200 metres of a water-based local nature reserve or national nature reserve
• 50 metres of a chalk river, water-based Local Wildlife site, or water-based protected habitat that the Environment Agency considers is at risk from this activity

For a site in tidal water ‘500 metres upstream’ means within 500 metres by the shortest distance over water in any direction from the nearest boundary of any of these sites. Only those sites that are water-based and hydraulically linked to the receiving water downstream of the discharge point are included in this rule.

11.1 How to check the locations of protected sites

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

1. Search for the discharge site location.
2. 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)’ and ‘Ramsar Sites (England)’.
3. In the table of contents, open ‘Habitats and Species’, then ‘Habitats’, then ‘Woodland’ option. Select ‘Ancient Woodland (England)’.
4. To measure the distance from the discharge site to any protected sites, select the ‘Measure’ tool from the menu then use the ‘Distance’ option.
5. To find out if a site is a biological SSSI, select the ‘Identify’ tool from the menu, then select the protected site on the map. Open the site detail link to read the description.

If you cannot use Magic map, or you need to check the location of protected habitats and species not contained within Magic map, then contact the Environment Agency to request a nature and heritage conservation screening.

12. Get your treatment system regularly maintained

You should have your treatment system serviced and maintained in line with the manufacturer’s instructions and a minimum of once every 12 months. If you do not have the manufacturer’s instructions, then ask your local maintenance company for advice.

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

12.1 Get your treatment system regularly emptied

You must get the sludge that builds up in your 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.

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 certificate

13. Check your new discharge is not within 50 metres of any other exempt or permitted sewage effluent discharge

Ask your neighbours if they have a sewage effluent discharge and, if so, ask how far their discharge is from your discharge location.

You must apply for a bespoke permit for the new discharge if it’s within 50 metres of any other exempt or permitted sewage effluent discharge.

For existing discharges, the term ‘at the time the discharge is first made’ refers to the date that the original discharge commenced.