Fact 28. Septic Tanks - how are they dealt with in conveyancing

Septic tanks must comply with current regulations, be fully disclosed and inspected, with upgrades or agreements addressed early in the conveyancing process to prevent legal or sale issues.

They are are a common off-grid wastewater solution for homes without access to mains drainage, most frequently found in rural or remote areas. They are designed as underground chambers that settle and retain solid sewage, letting liquid effluent soak away into the ground through a specifically engineered drainage field, and rely on natural bacterial processes for treatment. Domestic wastewater from toilets, sinks, showers, and appliances flows into the septic tank, with sludge periodically removed by a registered waste contractor to prevent clogs and pollution.

Homeowners or occupiers are legally responsible for ensuring their chosen wastewater system complies with current government guidelines and is properly maintained. This applies whether you own the property, share the system with others (joint liability), or are a tenant with responsibility for the system in your lease. If you connect to the public foul sewer, you need not take further steps; otherwise, all discharge management falls under your control.

Regulatory Framework and General Binding Rules

Recent years have seen significant legal developments around septic tanks, spearheaded by the introduction of the General Binding Rules (GBR) for small sewage discharges. The GBR were established to improve environmental protection and water quality, notably restricting how and where septic tanks can discharge treated liquid.

Key rule highlights include:

- All septic tanks must avoid polluting groundwater or surface water.

- Only domestic sewage is permitted for discharge.

- The discharge volume must remain within set daily limits (typically under 5 cubic metres per day).

- Maintenance is required to prevent pollution.

- Discharge into a watercourse (river, stream, ditch) is now generally prohibited—systems must discharge to a drainage field or a compliant sewage treatment plant.

- All work must meet relevant British Standards, specifically BS EN 12566 for tanks and BS 6297:2007 for drainage fields.

- Reed beds or converters can sometimes be used for compliance in certain ground conditions, but only under expert guidance.

Obligations for Operators

Whether you’re buying or selling a property, these rules place binding obligations on the responsible party (the ‘operator’):

1. Provide written notice to buyers outlining the sewage system, location, maintenance history, and discharge routes.

2. Demonstrate the system’s legal compliance, including upgrades where required, such as stopping discharges to watercourses or installing sewage treatment plants with EN 12566-3 certification.

3. Commission regular maintenance for sludge removal and system servicing.

4. Keep clear records for all works, as buyers will request evidence before completing the purchase.

5. If the tank or system does not comply, upgrade works or connection to a public foul sewer may be legally required. Only where these options are unreasonable can a permit be sought. Operating without required permits is unlawful.

Legacy Systems and 2020 Law Changes

Septic tanks installed before 1983 occupy a unique position in conveyancing. While not required to meet British Standards from that era (as none were in force), these old systems must now comply with new environmental laws. The rules introduced or reinforced in 2015 and 2020 prohibit direct discharges into watercourses, meaning even legacy tanks need upgrading or redirected discharges.

If an older septic tank does not meet GBR or causes pollution, sellers must take remedial action before selling. Buyers need to check installation dates and discharge practices, as any direct discharge to water prior to 1983 now breaches today’s standards. Failure to comply exposes both parties to substantial fines and enforcement action from the Environment Agency.

Distinguishing Existing and New Discharges

The regulatory distinction between 'existing' and 'new' discharges is important:

- Existing discharge: System installed or unchanged since before 2 October 2023. These may retain certain grandfathered rights but are still subject to compliance and, if not met, require upgrades or remediation.

- New discharge: Began or changed significantly after 2 October 2023. Must demonstrate full compliance from outset; if possible, must connect to a public sewer if ‘reasonable’, otherwise install a modern sewage treatment plant or compliant drainage system.

If the system doesn’t meet the GBR, connection or upgrades are required. Permits are only granted as a last resort when no other solutions are viable.

Selling or Buying with a Septic Tank

The implications for conveyancing are substantial:

- Sellers must disclose all details about the septic tank, its compliance status, maintenance history, and planned upgrades.

- Buyers should commission a report from specialist contractors, check for historic or ongoing pollution, and ensure the system complies before exchanging contracts.

- If upgrades are needed—such as replacing tanks discharging to watercourses—these must be negotiated early in the process. Funding responsibility should be clearly allocated in the purchase contract to avoid disputes.

- Documentation (planning approval, building regulations, maintenance records) will be required by buyers and, frequently, by mortgage lenders.

If the tank or treatment plant is shared, legal rights of access and maintenance need clear documentation as well.

Permitting and Enforcement

If you cannot meet GBR, a permit from the Environment Agency must be obtained. Selling, installing, or operating a non-compliant system without a permit is illegal; the Agency will not grant permits if compliance is reasonably achievable. The permit process involves submission of technical data, grid references, maximum discharge volumes, and an application fee that varies by site type and daily discharge.

For sewage discharges to the ground or water, specific forms and classifications apply depending on flow rates and whether the property is within a groundwater protection zone. Commercial sites have additional requirements, with fees and eligibility criteria.

Practical Advice and Key Points

- If your property has a septic tank, confirm it meets all relevant standards and binding rules.

- For tanks installed before 1983, check compliance with the latest regulations, especially regarding discharge location.

- Maintain the tank and keep a record of sludge removals and system servicing.

- Make arrangements for necessary upgrades before considering sale.

- For buyers, do not proceed without a specialist report and full system transparency.

- All parties should be aware that enforcement of wastewater standards is growing stricter—UK watercourses and the environment are increasingly protected by law, and non-compliance can affect property value, transaction speed, and finance availability.