Buying a property with a septic tank: what buyers need to know

For properties that are not connected to the public sewer network, septic tanks provide an alternative means of managing wastewater and are particularly prevalent in rural areas.

Questions about ownership, maintenance responsibilities, environmental compliance, and shared-use arrangements can all become important considerations during the conveyancing process.

Understanding how the system operates and who is responsible for it can help buyers avoid unexpected costs after completion.

If you are purchasing a property with a septic tank or other private drainage system, contact our solicitors for advice to help identify potential issues before they affect your transaction.

What is a septic tank?

A septic tank is a private drainage system that collects and treats wastewater from a property where mains drainage is unavailable.

Wastewater enters the tank, where solids settle, before the liquid waste is discharged into a drainage field or another approved drainage system.

Many rural properties operate septic tanks perfectly well for decades without issue, provided the systems are properly maintained and comply with current regulations.

Does the septic tank comply with current regulations?

One of the first issues buyers should consider is whether the system complies with the relevant environmental rules.

In England, septic tanks which discharge directly into watercourses are generally prohibited unless an exemption applies or the system has been upgraded.

Buyers should therefore establish:

• The type of drainage system in place.
• Where the system discharges.
• Whether any permits or exemptions apply.
• Whether any recent upgrades have been carried out.
• Whether any compliance issues have previously been identified.

Where concerns arise, further investigations may be required before the transaction can proceed.

Who owns the septic tank and who is responsible for maintaining it?

The answer will vary from property to property. Some systems serve a single property and are owned entirely by that homeowner.

Others are shared between neighbouring properties, with maintenance costs divided between multiple owners.

Buyers should understand:

• Who owns the system.
• Who is responsible for repairs and maintenance.
• How ongoing costs are shared.
• Whether formal agreements exist between neighbouring properties.
• Whether there is a history of disputes regarding maintenance contributions.

Unexpected repair or replacement costs can sometimes be significant.

What information will be provided during conveyancing?

The seller will usually be asked to provide information regarding the drainage arrangements serving the property.

This may include:

• Details of the drainage system.
• Maintenance records.
• Emptying arrangements.
• Details of any shared ownership arrangements.
• Information regarding any known defects or repairs.
• Compliance with current regulatory requirements. (For example, Environmental Health’s general binding rules).

Reviewing this information carefully can help buyers understand both their obligations and any likely future costs. 

Buyers purchasing a rural property may also need to consider a range of other issues relating to the land, access, boundaries and services, which we cover in our guide to rural property conveyancing.

Can mortgage lenders have concerns about septic tanks?

Sometimes. Mortgage lenders generally expect drainage arrangements to be lawful, operational, and adequately maintained.

Where there is uncertainty about ownership, compliance, or environmental issues, lenders may require additional information before releasing mortgage funds. Clarifying these issues early can help avoid delays later in the transaction.

What legal work is involved?

Advice on purchasing a property with a septic tank may involve:

• Reviewing drainage arrangements and ownership documentation.
• Investigating compliance with environmental requirements.
• Reviewing rights relating to drainage fields and pipework.
• Investigating shared maintenance arrangements where applicable.
• Raising enquiries regarding repairs, maintenance and ongoing obligations.

Common issues with septic tanks

A variety of issues can arise with a property served by a private drainage system such as a septic tank. For example: non-compliance with Environmental Health’s general binding rules. These rules set out the requirements which must be met to use a septic tank without an environment permit. Non-compliance can include but is not limited to: discharging into streams or rivers; exceeding the daily maximum discharge amount and/or not meeting the relevant British Standard which was in place at the time the drainage system was installed.

Failure to comply with the general binding rules could result in your mortgage provider refusing to lend without evidence proving compliance. Further information for these rules can be found on the GOV.UK website.

Other common issues include missing documentation and unclear responsibility for maintenance and costs for shared systems. Lack of maintenance records can make it difficult to ascertain the condition of the system and could result in unexpected maintenance and repair costs post completion. Similarly, a shared system with no legal agreement in place could place you at risk of a dispute with neighbours over shared responsibilities, which could incur additional legal costs.

How can buyers reduce risk?

Private drainage systems are common across many rural parts of England and Wales and are often straightforward to manage.

However, buyers should ensure they understand how the system operates, who is responsible for it and whether any future expenditure is likely before proceeding with the purchase.

Identifying issues early can help avoid unexpected liabilities after completion.

Guidance from our solicitors

Properties with private drainage systems often involve issues that do not arise in standard residential transactions and may require additional investigations into ownership arrangements, environmental compliance, and maintenance obligations.

Joe Kennedy, solicitor and deputy head of residential property, comments:

“Arranging a private drainage survey to be carried out early in your transaction ensures issues are brought to light at the outset and can help avoid delays. Understanding the relevant arrangements of the private drainage system is vital to ensure that you have adequate information of your obligations and can avoid unexpected liabilities which could arise post-completion.”

Our residential property solicitors regularly advise buyers purchasing rural and non-standard properties across East Sussex, Cumbria, Bath and the surrounding areas.

Where transactions involve larger rural properties, additional land or more complex ownership arrangements, we can also draw on expertise from our commercial property and development teams to provide joined-up advice across the wider transaction.

If you are considering purchasing a property with a septic tank or private drainage system, our solicitors can help you understand the implications and make an informed decision before proceeding.