Statutory guidance

SR2025 No 7: 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

The Environmental Permitting (England & Wales) Regulations 2016

Introductory note

This introductory note does not form a part of these standard rules.

When referred to in an environmental permit, these rules will allow the operator to undertake:

• a discharge of secondary treated domestic sewage effluent with a maximum daily volume of 5 cubic metres per day to surface water where secondary treatment is achieved using equipment that does not conform to the British Standard or where the receiving watercourse does not always have flow, or both
• discharges using works and equipment which are not British Standard must be existing discharges to surface water and must be secondary treated. The sewage treatment plant shall be designed, operated and maintained so as to ensure that any effluent discharged does not contain concentrations in excess of 20 milligrams per litre of ATU-BOD as O₂, 30 milligrams per litre of suspended solids (measured after drying at 105°C), or 20 milligrams per litre of ammoniacal nitrogen (expressed as N). Prior to installation of the works and equipment, the operator shall obtain evidence from the installer that the sewage treatment system is capable of consistently treating the effluent to the required standards
• where the receiving watercourse does not always have flow, the discharge must be secondary treated, and the sewage treatment plant shall be designed, operated and maintained so as to ensure that any effluent discharged does not contain concentrations in excess of 20 milligrams per litre of ATU-BOD as O₂, 30 milligrams per litre of suspended solids (measured after drying at 105°C), or 20 milligrams per litre of ammoniacal nitrogen (expressed as N). If the discharge takes place on a principal or secondary A aquifer, then the sewage treatment plant shall be designed, operated and maintained so as to ensure that any effluent discharged does not contain concentrations in excess of 20 milligrams per litre of ATU-BOD as O₂, 30 milligrams per litre of suspended solids (measured after drying at 105°C), or 10 milligrams per litre of ammoniacal nitrogen (expressed as N)
• where the receiving watercourse does not always have flow, the discharge must be made via a length of perforated pipe. The extent of the perforated pipe shall be sufficient to ensure that the discharge is only made when the receiving watercourse is flowing. Any section of perforated pipe must be located within 10 metres of the bank of the receiving watercourse
• the sewage must be domestic sewage containing no trade effluent (as defined in Section 221 of the Water Resources Act 1991). All equipment must be sized in accordance with the current edition of “Flows and Loads” and managed, operated and maintained in accordance with the manufacturer’s recommendations
• the discharge must not be made into surface waters within 500 metres upstream from a European site, Ramsar site, biological Site of Special Scientific Interest (SSSI), freshwater pearl mussel population, designated bathing water, Marine Conservation Zone, protected shellfish water, any body of water identified as containing a Protected Species, 200 metres of a water-based local nature reserve or National Nature Reserve or 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 ‘500m upstream’ means within 500 metres by the shortest distance over water in any direction from the nearest boundary of any of these sites
• this restriction only applies to conservation sites that are water-based and hydraulically linked to the receiving water downstream of the discharge point
• the discharge must not be made to a lake or pond
• where the receiving watercourse does not always have flow, the discharge must not be made within a groundwater source protection zone 1 (SPZ1) or within 125 metres of any well, spring or borehole that is used to supply water for domestic drinking or food production purposes
• at the time the discharge is first made, it must not be made to a discharge point within 50 metres of any other exempt or permitted sewage effluent discharge to ground or surface water.
• all works on the equipment (for example, installation, servicing and testing) must be undertaken by a competent person and it is recommended that the person has a relevant accreditation, for example the British Water accreditation for treatment plant service technicians or manufacturer accreditation for installation

End of introductory note

Rules

1. Management

1.1 General management

1.1.1 The operator shall manage and operate the activity:

(a) in accordance with a written management system that identifies and minimises risks of pollution, so far as is reasonably practicable, including those risks arising from operations, maintenance, accidents, incidents, non-conformances and those drawn to the attention of the operator as a result of complaints; and

(b) using sufficient competent persons and resources.

1.1.2 Records demonstrating compliance with rule 1.1.1 shall be maintained. 

1.1.3 Any person having duties that are or may be affected by the matters set out in these standard rules or the permit shall have convenient access to a copy of the permit and the rules. 

2. Operations

2.1 Permitted activities

2.1.1 The only activity authorised by the permit is the discharge of secondary treated domestic sewage effluent with a maximum daily volume of up to and including 5 cubic metres per day to surface water.

The activity is limited to:

(a) the maximum daily volume shall be no greater than 5 cubic metres per day as calculated by the method specified in the current edition of “Flows and Loads”

(b) the sewage shall be solely domestic sewage and contain no trade effluent (as defined in Section 221 of the Water Resources Act 1991)

(c) discharges using works and equipment which are not British Standard must be an existing discharge to surface water and must be secondary treated. The sewage treatment plant shall be designed, operated and maintained so as to ensure that any effluent discharged does not contain concentrations in excess of 20 milligrams per litre of ATU-BOD as O₂, 30 milligrams per litre of suspended solids (measured after drying at 105°C), or 20 milligrams per litre of ammoniacal nitrogen (expressed as N). Prior to installation of the works and equipment, the operator shall obtain evidence from the installer that the sewage treatment system is capable of consistently treating the effluent to the required standards. This evidence must be kept with the management system documentation.

(d) where the receiving watercourse does not always have flow, the discharge must be secondary treated, and the sewage treatment plant shall be designed, operated and maintained so as to ensure that any effluent discharged does not contain concentrations in excess of 20 milligrams per litre of ATU-BOD as O₂, 30 milligrams per litre of suspended solids (measured after drying at 105°C), or 20 milligrams per litre of ammoniacal nitrogen (expressed as N). If the discharge takes place on a principal or secondary A aquifer, then the sewage treatment plant shall be designed, operated and maintained so as to ensure that any effluent discharged does not contain concentrations in excess of 20 milligrams per litre of ATU-BOD as O₂, 30 milligrams per litre of suspended solids (measured after drying at 105°C), or 10 milligrams per litre of ammoniacal nitrogen (expressed as N)

(e) the sewage shall not contain a significant proportion of rainwater or groundwater

(f) prior to the discharge, the sewage must have received secondary treatment

(g) for discharges in tidal waters, the discharge outlet must be below the mean spring low water mark

(h) the boundary of the premises that the sewage treatment system serves must not be within 30 metres of a public foul sewer. If the sewage treatment system serves more than one property, then it must not be within a distance that is less than 30 metres multiplied by the number of properties served

(i) if some or all of the discharge is from non-domestic properties, then the maximum volume in cubic metres that is being discharged from those other premises should be divided by 0.75 and the result multiplied by 30. The result is a distance in metres and no boundary of the premises that the sewage treatment system serves can be within that distance of a public foul sewer

(j) at the time the discharge is first made, it must not be made to a discharge point within 50 metres of any other exempt or permitted sewage effluent discharge to groundwater or surface water

(k) where the receiving watercourse does not always have flow, the discharge must be made via a perforated pipe. Any section of perforated pipe must be located within 10 metres of the bank of the receiving watercourse, but this perforated section shall not extend more than 10 metres from the bank of any watercourse

(l) no part of the perforated pipe shall be more than 2 metres below ground level or below the level of the bed of the receiving watercourse

(m) the discharge directly to the receiving watercourse shall only be made when there is flow in the watercourse immediately upstream of that discharge point, as far as reasonably practicable. At all other times the discharge shall be made indirectly to the receiving watercourse via the soil surrounding the perforated pipe and as such, the length of perforated pipe installed should be designed appropriately to ensure this occurs

(n) the discharge point to the receiving watercourse must be sited and constructed so that the discharge will not cause a nuisance or harm to human health

(o) the works and equipment shall be serviced a minimum of once every 12 months (or more if required by the manufacturer’s specifications) by a competent and suitably qualified person. Records demonstrating compliance with this rule shall be maintained by the operator

(p) no chemical dosing or electrocoagulation shall be used as part of the effluent treatment process

2.2 The site 

2.2.1 The discharge activity shall take place at the discharge point marked on the site plan attached to the permit.

2.2.2 The discharge shall not be made into surface waters within:

(a) 500 metres upstream from the nearest boundary of a European site, Ramsar site, biological SSSI, freshwater pearl mussel population, designated bathing water, Marine Conservation Zone, protected shellfish water, any body of water identified as containing a Protected Species or 200 metres of a water-based local nature reserve or National Nature Reserve;

(b) 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 ‘500m upstream’ means within 500 metres by the shortest distance over water in any direction from the nearest boundary of any of these sites. Of the sites listed in (a) and (b), only those that are water-based and hydraulically linked to the receiving water downstream of the discharge point are included in this rule.

2.2.3 The discharge must not be made to a lake or pond.

2.2.4 Where the receiving watercourse does not always have flow, the discharge must not be made within a groundwater SPZ1 or within 125 metres of any well, spring or borehole that is used to supply water for domestic drinking or food production purposes.

2.2.5 At the time the discharge is first made, it must not be made to a discharge point within 50 metres of any other exempt or permitted sewage effluent discharge to ground or surface water. 

3. Emissions and monitoring

3.1 Emissions to water

3.1.1 The limits given in table 3.1 shall not be exceeded.

Table 3.1 Point source emissions to water and land – emission limits and monitoring requirements

Emission point and source	Parameter	Limit (including unit)	Monitoring frequency and standard or method
Discharge point for secondary treated domestic sewage effluent	Maximum daily discharge volume	5 cubic metres per day	Not applicable
Discharge point for secondary treated domestic sewage effluent	Visual appearance and other environmental effects	The discharge must so far as is reasonably practicable have no significant adverse visible effect on the receiving water, the bed of the watercourse or any plants or animals within the watercourse	See Table 3.3

3.2 Emissions of substances not controlled by emission limits

3.2.1 The operator shall take appropriate measures to minimise so far as reasonably practicable the polluting effects of the emissions of substances in the discharge not controlled by emission limits (excluding odour).

3.3 Monitoring 

3.3.1 An accessible monitoring point shall be provided and maintained to enable monitoring to be carried out at the monitoring point marked on the site plan attached to the permit.

3.3.2 The operator shall, unless otherwise agreed in writing by the Environment Agency, undertake monitoring for the parameters, at the locations and at not less than the frequencies specified in Table 3.3. 

3.3.3 The operator shall maintain records of all monitoring required by these standard rules.

Table 3.3 Activities – monitoring requirements

Monitoring point	Parameter	Monitoring frequency	Monitoring method	Other specifications
Discharge point for secondary treated sewage	Visual appearance and other environmental effects	Weekly	Visual examination	The discharge must so far as is reasonably practicable have no significant adverse visible effect on the receiving water, the bed of the watercourse or any plants or animals within the watercourse.

4. Information

4.1 Records

4.1.1 All records required to be made by conditions 2.1.1, 3.3.3 and 4.3.2 shall:

• be legible;
• be made as soon as reasonably practicable;
• if amended, be amended in such a way that the original and any subsequent amendments remain legible, or are capable of retrieval; and
• be retained, unless otherwise agreed in writing by the Environment Agency, for at least 6 years from the date when the records were made.

4.1.2 The operator shall maintain convenient access, in either electronic or hard copy, to the records, plan and management system required to be maintained by these standard rules. 

4.2 Reporting

4.2.1 The operator shall send all reports and notifications required by these standard rules to the Environment Agency using the contact details supplied in writing by the Environment Agency.

4.3 Notifications

4.3.1 The Environment Agency shall be notified as soon as reasonably practicable following detection, within the site of the regulated facility of:

(a) any malfunction, breakdown or failure of equipment or techniques, accident, or emission of a substance not controlled by an emission limit which has caused, is causing or may cause significant pollution; and

(b) any breach of a limit specified in these standard rules.

Any other significant adverse environmental effects, which may have been caused by the activity, shall also be notified to the Environment Agency as soon as reasonably practicable following detection.

4.3.2 Written confirmation of actual or potential pollution incidents and breaches of emission limits shall be submitted within 24 hours.

4.3.3 The Environment Agency shall be notified within 14 days of the occurrence of the following matters, except where such disclosure is prohibited by Stock Exchange rules:

Where the operator is a registered company:

• any change in the operator’s trading name, registered name or registered office address; and
• any steps taken with a view to the operator going into administration, entering into a company voluntary arrangement or being wound up.

Where the operator is a corporate body other than a registered company:

• any change in the operator’s name or address; and
• any steps taken with a view to the dissolution of the operator.

In any other case:

• the death of any of the named operators (where the operator consists of more than one named individual);
• any change in the operator’s name(s) or address(es); and
• any steps taken with a view to the operator, or any one of them, going into bankruptcy, entering into a composition or arrangement with creditors, or, in the case of them being in a partnership, dissolving the partnership.

4.3.4 Where the operator proposes to make a change in the nature of the activity by increasing the concentration of, or the addition of, or allowing the introduction of, a substance to the activity to an extent that the operator considers could have a significant adverse environmental effect on the receiving waters, and the change is not permitted by emission limits specified within these standard rules and the change is not the subject of an application for approval under the EP Regulations or under the terms of this permit:

• the Environment Agency shall be notified in writing at least 14 days before the increase or addition or allowing the introduction; and
• the notification shall contain a description of the proposed change.

4.4 Interpretation

4.4.1 In these standard rules the expressions listed below shall have the meaning given.

4.4.2 In these standard rules references to reports and notifications mean written reports and notifications, except where reference is made to notification being made “as soon as reasonably practicable”, in which case it may be provided by telephone.

“Accident” means an accident that may result in pollution.

“Application” means the application for this permit, together with any additional information supplied by the operator as part of the application and any response to a notice served under Schedule 5 to the EP Regulations.

“Appropriate measures” for the purposes of the emission of substances not controlled by emission limits condition (condition 3.2.1) do not require the operator to undertake treatment to a level beyond that specified in condition 2.1.1, or to carry out routine monitoring for substances not controlled by emission limits.

“ATU-BOD” means biochemical oxygen demand with nitrification suppressed by the addition of allylthiourea.

“Biological SSSI” means for the purpose of these standard rules either:

(a) a SSSI which has been designated due to the presence of flora or fauna.

(b) a SSSI that contains surface water or springs that can provide habitat for flora or fauna.

“Boundary of the premises” means the general boundary as shown on the registered title deeds, under section 60(1) of the Land Registration Act 2002.

“BS 12566” means BS EN 12566-3:2005 “Small wastewater treatment systems for up to 50 PT. Packaged and/or site assembled domestic wastewater treatment plants” (ISBN: 0 580 47444 5 Publication Date: 15th Feb 2006).

“Chemical dosing” means the addition of chemicals specifically to enhance the sewage treatment process, either passively or actively. For example, the additional of chemicals to reduce the level of certain pollutants, control odours or aid sludge settlement.

“Domestic sewage” means wastewater from residential settlements and services which originates predominantly from the human metabolism and from household activities. See our website for further details. 

“Electrocoagulation” means a process that involves the in-situ generation of coagulant agents through the dissolution of sacrificial electrodes under a direct current and the subsequent removal of suspended particles and pollutants from the effluent.

“Emissions of substances not controlled by emission limits” means emissions of substances to air, water or land from the permitted activities, which are not controlled by an emission limit.

“EP Regulations” means The Environmental Permitting (England and Wales) Regulations SI 2016 No.1154 and words and expressions used in this permit which are also used in the Regulations have the same meanings as in those Regulations.

“European site” means a European site within the meaning of Regulation 8 of the Conservation of Habitats and Species Regulations 2017, or a site referred to in the National Planning Policy Framework 2024 as requiring the same assessment as a European site. 

“Every 12 months” means a rolling 12 months starting from the time of first operation of the sewage treatment system.

“Existing Discharge” means a discharge that was in place and discharging directly to the same watercourse before 2 October 2023.

“Flows and Loads” means the version of “Flows and Loads - Sizing Criteria, Treatment Capacity for Small Wastewater Treatment Systems (Package Plants)” published by British Water (ISBN: 978-1-903481-10-3) applicable at the date of issue of this permit. 

“Groundwater Source Protection Zone 1” means a zone:

(a) within 50 metres of a point at which water is abstracted for domestic or food production purposes from any underground strata, or

(b) defined by a 50-day travel time for groundwater to reach a groundwater abstraction point that is used to supply water for domestic or food production purposes, whichever is larger.

“Lake or pond” for the purposes of these standard rules means any relevant lake or pond as defined by section 104(3) Water Resources Act 1991.

“Local Nature Reserve” means an area designated by a local authority under the National Parks and Access to the Countryside Act 1949. 

“Local Wildlife site” is a non-statutory designation by a local authority of sites with a high value for wildlife. They are designated according to selection criteria that follow Natural England or the Countryside Council for Wales guidelines. 

“Marine Conservation Zone” means a Marine Conservation Zone as designated under the Marine and Coastal Access Act 2009.

“Pollution” means the direct or indirect introduction, as a result of human activity, of substances or heat or biological entities or micro-organisms into air, water or land which may: 

• be harmful to human health or the quality of aquatic ecosystems or terrestrial ecosystems directly depending on aquatic ecosystems; 

• result in damage to material property; or
• impair or interfere with amenities and other legitimate uses of the environment.

“Principal aquifer” means geological strata which

(a) exhibit a high intergranular or fracture permeability, and

(b) provide a high level of water storage and support water supply or base flow to rivers, lakes and wetlands on a strategic scale.

“Protected species and habitats” mean species and habitats that may be of principal importance, as listed in Section 41 of the Natural Environment and Rural Communities Act 2006 or protected under the Conservation of Habitats and Species Regulations 2017 or Wildlife and Countryside Act 1981, and that the Environment Agency considers to be at risk from the activity.

“Ramsar site” means a wetland of international importance, designated under the Ramsar Convention (an international agreement signed in Ramsar, Iran, in 1971). It is government policy to treat Ramsar sites the same as European sites. 

“Secondary A aquifer” means permeable strata capable of supporting water supplies at a local rather than strategic scale.

“Secondary B aquifer” means predominantly lower permeability strata including where they have, in part, the ability to store and yield limited amounts of groundwater by virtue of localised features such as fissures, thin permeable horizons or weathering.

“Secondary treatment” means treatment of the domestic sewage by a process generally involving biological treatment with a secondary settlement or other process. Note that “secondary treatment” under these rules is “appropriate treatment” for the purposes of the Regulations.

“Secondary undifferentiated” means rock deposits or strata with variable permeability and storage properties which are not consistently a secondary A aquifer or secondary B aquifer.

“Significant adverse visible effect” means dead or distressed fish, other animals or plants in the vicinity of the discharge, appreciable deposit of solid material; significant growth of sewage fungus; appreciable discolouration.

“Significant pollution” means a category 1 or category 2 incident indicated by the Common Incident Classification Scheme (CICS). 

“SSSI” means Site of Special Scientific Interest within the meaning of the Wildlife and Countryside Act 1981 (as amended by the Countryside and Rights of Way Act 2000).

“Surface water” means inland freshwaters, coastal waters or relevant territorial waters (as defined in section 104 of the Water Resources Act 1991).

“Unproductive strata” means rock deposits or strata that are largely unable to provide usable water supplies and are unlikely to have surface water and wetland ecosystems dependent on them.

“Year” means calendar year commencing on 1 January.

End of standard rules