Sewage treatment regulations are important for any property that is not connected to mains drainage.
Property owners must ensure that systems are suitable, correctly installed, properly maintained and not causing pollution.
This guide summarises the main compliance points, but site-specific advice should always be taken before installation or upgrade work.
Quick Answer
In England, small sewage discharges may be allowed without an environmental permit if they meet the Environment Agency's General Binding Rules.
If the rules cannot be met, a permit or system upgrade may be required.
The general binding rules for septic tanks (England)
If your septic tank or sewage treatment plant meets the Environment Agency's general binding rules, you do not need a permit for its discharge. These are the main points:
Where it discharges. A septic tank must discharge to the ground through a drainage field. It must not discharge straight into a stream, river or ditch. Only a sewage treatment plant can discharge to surface water.
How much it discharges. Up to 2 cubic metres (2,000 litres) a day to the ground, or up to 5 cubic metres (5,000 litres) a day from a treatment plant to surface water.
The standard it meets. The system must meet the British Standard that applied when it was installed: BS EN 12566 for new tanks and plants, and BS 6297 for drainage fields. Systems installed before 1983 do not need to meet a British Standard but must follow the other rules.
Maintenance and emptying. Keep it maintained as the manufacturer says, repair it if it is not working properly, and have the sludge removed by a registered waste carrier before the tank gets too full: at least once a year, or as the manufacturer says.
Selling the property. Tell the buyer in writing that there is a sewage discharge, with a description of the system, where its main parts are, any changes made and any maintenance records you have.
When the rules do not apply. You will need a permit or a different solution if, for example, a public foul sewer is within 30 metres of the property boundary, the discharge is in a groundwater source protection zone 1, it is close to a protected nature site, or it is bigger than the limits above.
The 2020 deadline. Septic tanks discharging straight to a watercourse were meant to be upgraded by 1 January 2020. If yours still does, you must act as soon as possible: connect to the mains sewer, replace the tank with a sewage treatment plant, or install a drainage field.
This summary reflects the Environment Agency guidance on GOV.UK as at October 2026. Wales has different rules.
Planning and Building Regulations
Even where a full environmental permit is not required, building regulations or planning requirements may still apply.
Protected locations, groundwater source protection zones and sensitive landscapes may create extra restrictions.
Owner Responsibilities
The property owner or operator is responsible for ensuring the system is maintained and operated correctly.
Systems should be serviced, emptied where required and repaired promptly if faults appear.
Property Sales
Drainage compliance can become important during a property sale. Buyers may ask for servicing records, discharge details and evidence that the system complies.
A non-compliant system can delay a transaction or lead to negotiation around upgrade costs.
Get Compliance Support
Alton Facility Services can inspect off-mains drainage systems, advise on compliance risks and recommend upgrades where needed.
Need help? Contact our team or call 01420 561661.
Why rules affect the practical design
The discharge route, receiving watercourse, ground conditions and existing system all affect whether a repair, upgrade, conversion or full replacement is suitable.
Where a septic tank discharges to surface water, the practical solution is often a compliant treatment plant or redesigned drainage arrangement rather than a like-for-like repair.
How AFS would investigate this on site
For off-mains drainage issues, we would normally start by checking the tank or treatment plant, inlet and outlet pipework, alarms, pumps, blowers, sludge levels, drainage field condition and any signs of surcharge or pollution.
If the issue looks compliance-related, we would also consider whether the existing arrangement needs septic tank conversion, a new sewage treatment plant installation, or planned treatment plant maintenance rather than another temporary repair.
When this becomes urgent
You should treat the problem as urgent if sewage is backing up into the property, wastewater is escaping outside, alarms are sounding repeatedly, electrical equipment is wet, or the system is close to overflowing.
In those situations, stop unnecessary water use, keep people away from contaminated areas and arrange professional attendance. Where the system needs emptying before repair, sewage tanker services may be required to control the level safely.
Useful related AFS services
The most relevant AFS services for this topic are sewage treatment plant installation, treatment plant maintenance, septic tank conversion and sewage tanker services. These pages explain the practical options in more detail.
Need practical help with this?
For sewage treatment plants, septic tanks, private drainage systems and tanker support across Hampshire, Surrey and nearby areas, AFS can inspect the system and recommend the practical next step. You can call 01420 561661 or send details through the contact form.
Call AFS on 01420 561661 or send the details through for practical advice.
Contact AFSFrequently asked questions
Who enforces sewage treatment regulations?
The Environment Agency is responsible for enforcing environmental permitting and small sewage discharge rules in England.
Do all systems need a permit?
Not always. A permit may not be needed if the system meets all relevant General Binding Rules.
Can a septic tank discharge to a stream?
No. Septic tanks are not suitable for direct discharge to a watercourse.
What happens if my system is not compliant?
You may need to repair, upgrade or replace the system, and enforcement action may be possible in serious cases.
Should I get advice before replacing a system?
Yes. The correct solution depends on site conditions, discharge route, usage and local restrictions.
Can AFS inspect a private sewage system before quoting?
Yes. For sewage treatment plants, septic tanks, pump chambers and private drainage systems, AFS can inspect the site, identify the likely cause and advise whether servicing, repair, tanker attendance, conversion or replacement is appropriate.
What are the general binding rules for septic tanks?
They are the Environment Agency conditions for small sewage discharges in England. If your system meets them, for example discharging to a drainage field within the volume limits, properly maintained and emptied by a registered waste carrier, you do not need a permit.
Do the 2020 septic tank rules still apply?
Yes. A septic tank must not discharge straight to a stream, river or ditch. If yours does, it needs upgrading as soon as possible: replace it with a sewage treatment plant, install a drainage field or connect to the mains sewer.