The Environment Agency has clarified when engineered ground can be used for a small sewage discharge to ground in England. Here is what changed, what the general binding rules mean, and what sewage treatment plant owners should check.
The Environment Agency updated its guidance on 23 July 2026. The update adds specific conditions under which ground engineered to reduce its percolation rate can meet the general binding rules.
What are the general binding rules?
The general binding rules are the conditions that operators of septic tanks and small sewage treatment plants in England must follow when discharging treated domestic sewage to the environment. If your discharge meets all the general binding rules that apply to it, you will normally not need an environmental permit for the discharge.
The rules cover matters such as the amount and type of sewage being discharged, the treatment system and drainage field, where the discharge is located, installation and operation of the system, maintenance and preventing pollution. The exact rules that apply can depend on when the discharge started or was significantly changed.
This article focuses on discharges to ground. Separate Environment Agency guidance applies to discharges to surface water.
What changed in July 2026?
A discharge to ground that has been engineered to reduce its percolation rate can meet the general binding rules only when all three of the following conditions are satisfied:
- The discharge is not in a floodplain.
- The engineered ground has a minimum percolation value (Vp) of 15.
- The drainage field is located, designed and constructed in line with all other recommendations in BS 6297:2007.
This is a clarification of the Environment Agency's guidance for discharges to ground. It is not a blanket approval for every site that uses imported or modified soil.
What does Vp 15 mean?
Vp is the percolation value obtained from a percolation test. It indicates how quickly water moves through the ground and is used when assessing and designing a drainage field. The updated guidance sets a minimum Vp of 15 for ground deliberately engineered to reduce the percolation rate.
Meeting that single figure is not enough by itself. The site must also be outside a floodplain and the drainage field must comply with the other relevant recommendations in BS 6297:2007. A competent designer or installer should assess the whole installation.
What has not changed?
The general binding rules still require operators to meet all the conditions applying to their discharge. Among other things, a discharge to ground must:
- Contain domestic sewage only.
- Be 2 cubic metres (2,000 litres) a day or less unless an environmental permit is obtained.
- Avoid causing pollution of surface water or groundwater.
- Use the correct treatment system and drainage field.
- Meet the applicable siting, installation, capacity and British Standard requirements.
Different additional rules apply according to when the discharge started or changed. The July update applies to England; Scotland, Wales and Northern Ireland have their own regulators and guidance.
Why pump maintenance matters
The general binding rules require a treatment system to be installed and operated in accordance with the manufacturer's specification. Environment Agency guidance also says the system must be repaired or replaced if it is not in good working order. Examples given by the Environment Agency include a failed motor, failed pump or failed electrical supply.
If your treatment plant relies on an air blower, a failed or poorly performing pump can affect the treatment process. Do not ignore an alarm, unusual silence, reduced airflow or persistent sewage smells.
A practical maintenance checklist
- Follow the treatment plant manufacturer's servicing schedule.
- Check alarms and electrical supplies rather than assuming the air pump itself has failed.
- Inspect air filters and airflow in line with the pump manufacturer's instructions.
- Arrange prompt diagnosis by a competent service engineer if the plant is not operating normally.
- Use the exact plant and pump model when sourcing a replacement or repair kit.
- Keep maintenance and desludging records for the property.
If changing more than a component or making a significant alteration to the treatment system, check whether this affects how the discharge is classified under the rules.
What should treatment plant owners check?
- Confirm whether the system discharges to ground or surface water.
- Check which rules apply according to when the discharge began or was significantly changed.
- If engineered ground forms part of the drainage field, ask the designer or installer to confirm that the floodplain, Vp and BS 6297:2007 conditions are met.
- Make sure the plant is serviced, desludged and operating correctly.
- Seek advice from a competent service engineer or the Environment Agency if compliance is uncertain.
Further information
Read the Environment Agency guidance: General binding rules: small sewage discharge to the ground.
For replacement treatment-plant air pumps, filters and repair kits, browse the Greenleaf Pumps product range. Match the exact model and specification, or obtain competent advice if you are unsure.
Important: This article is a general summary for England, not legal, planning, drainage-design or site-specific compliance advice. Always check the current official guidance and consult the relevant regulator or a competent professional where necessary.