Septic Tanks and Sewage Treatment Systems in England

A Guide for Property Buyers and Sellers

If a property is not connected to the public sewer network, it will usually rely on a private drainage system. Understanding how these systems work, and the legal obligations associated with them, is important when buying or selling a property.

Types of Private Drainage Systems

Properties without mains drainage commonly use one of the following systems:

Septic Tanks

A septic tank collects wastewater and allows solids to settle at the bottom. The liquid waste then flows into a drainage field or infiltration system where it is naturally filtered through the ground. Septic tanks require regular emptying and maintenance.

Sewage Treatment Plants

A sewage treatment plant provides a higher level of treatment than a septic tank. The treated water may then be discharged into a watercourse or drainage field, subject to legal requirements.

Cesspits and Cesspools

These are sealed tanks that store sewage until it is removed by a licensed waste contractor. As there is no treatment process, they require frequent emptying and ongoing maintenance.

Alternative Systems

Some properties use non-standard arrangements such as reed beds or trench arch systems. These may require specialist advice and, in some cases, environmental permits.

The General Binding Rules

Most owners of septic tanks and small sewage treatment plants do not need an Environmental Permit, provided their system complies with the Environment Agency's General Binding Rules.

These rules are designed to prevent pollution and ensure private drainage systems operate safely and effectively. In general, owners must:

• Maintain the system properly.

• Ensure it does not cause pollution.

• Arrange regular servicing and emptying where required.

• Comply with any applicable environmental regulations.

When Might a Permit Be Required?

Specialist advice should always be obtained, but a permit may be required where:

• The discharge exceeds permitted daily volumes.

• The system is located within a sensitive environmental area.

• The discharge affects a drinking water source.

• The installation does not meet the criteria set out in the General Binding Rules.

JB Property Law cannot advise on the technical compliance of drainage systems. We recommend consulting a qualified drainage engineer, surveyor, or the Environment Agency where concerns arise.

Discharges to Surface Water

Current regulations do not generally allow septic tanks to discharge directly into rivers, streams, ditches, or other surface waters.

Where a property has a direct discharge, the system may need to be upgraded, replaced with a sewage treatment plant, connected to mains drainage, or modified to discharge through a compliant drainage field.

If a non-compliant system is identified during a transaction, buyers and sellers should discuss responsibility for any required upgrades before exchange of contracts.

Information Sellers Must Provide

When selling a property with a septic tank or sewage treatment system, owners should provide:

• A description of the drainage system.

• The location of key components and discharge points.

• Details of any alterations or upgrades.

• Maintenance requirements and manuals, where available.

• Maintenance records, if they exist.

This information is typically supplied through the standard property information forms completed during the conveyancing process.

Buying a Property with a Septic Tank

Purchasers should ensure they understand the condition and compliance status of any private drainage system before committing to a purchase.

We recommend confirming that the system:

• Is in good working order.

• Has sufficient capacity for the property.

• Does not cause pollution.

• Complies with relevant planning and building regulations.

• Benefits from any necessary rights of access and maintenance arrangements.

• Has appropriate agreements in place where the system is shared with neighbouring properties.

Where concerns are identified, buyers may wish to negotiate repairs, upgrades, or a price adjustment before exchange.

Older Systems

Many older drainage systems were installed under previous regulations and may not meet current standards. Issues can include:

• Leaking tanks.

• Inadequate soakaways.

• Lack of supporting documentation.

• Non-compliant discharge arrangements.

In some cases, specialist surveys may recommend improvements, replacement works, or permit applications.

Potential Costs

Additional costs may arise in connection with:

• Drainage surveys and inspections.

• Repairs or replacement of existing systems.

• Environmental permit applications.

• Ongoing maintenance and servicing.

These costs should be considered as part of the overall purchase decision.

Need Advice?

If you are buying or selling a property with a septic tank, sewage treatment plant, or other private drainage system, the team at JB Property Law can guide you through the conveyancing process and help identify when specialist drainage advice may be required.

Contact JB Property Law to discuss your transaction with one of our experienced property law specialists.