Designs That Work. Solutions That Last.

No. A correctly installed septic tank that meets either the Environment Agency’s General Binding Rules or the conditions of any permit that applies to it is entirely legal. The key requirement is that a septic tank must discharge into a drainage field or an appropriate soakaway – it cannot legally discharge directly into a ditch, watercourse or highway drain.

In our experience, the five most common compliance failures are:

A septic tank discharging directly into a ditch, watercourse or highway drain. Septic tanks must discharge to the ground via a drainage field.

A system that has failed due to a lack of maintenance – for example, a blocked or collapsed drainage field, damaged tankage, or ingress of rainwater into the system.

A tank that is significantly undersized for the current property, typically where bedrooms have been added without the foul drainage system being upgraded accordingly.

A system that requires a permit – for example, where discharge exceeds 2m³ per day to the ground, or the drainage field is within 50 metres of a private drinking water supply.

A system where the old septic tank has been replaced by a package sewage treatment plant, but the effluent was directed into plastic rainwater crates rather than a properly designed drainage field or watercourse – which is not a legal discharge point.

Yes – in principle. If you are purchasing a property without a mortgage, or you can satisfy your lender that the system will be brought into compliance within 12 months (the Environment Agency’s standard requirement), a sale can proceed. However, in practice, lenders will often refuse to lend on a property with a confirmed non-compliant system. If the sale does go ahead, the obligation to bring the system into compliance passes to you as the new owner. Most buyers in this situation negotiate a reduction on the purchase price to offset the cost of replacement. If you are involved in buying or selling a property with a private drainage system, contact us early – a compliance survey and a clear remediation plan can prevent delays and abortive costs.

No – not directly. However, where the only available discharge point is a watercourse that happens to flow through a pond, it may sometimes be possible to demonstrate to the Environment Agency that the treated water is carried through the pond quickly and does not stagnate. This is a technically complex argument and can be difficult to make successfully. Where possible, discharging directly into a watercourse leaving a pond is always preferable and will be the Environment Agency’s expectation. Contact us to discuss your specific site situation.

Under Section 23 of the Land Drainage Act 1991, consent is required before piping, culverting or obstructing a watercourse – whether permanently or temporarily. This can include installing new headwalls or outfall pipes, and in some cases may apply to repairs and maintenance works.

Who you need consent from depends on the location and classification of the watercourse:

If the watercourse is a Main River, you will need Flood Defence Consent from the Environment Agency.

If the watercourse is within a Drainage Board area (for example, the Axe Brue, Parrett or North Somerset Levels in Somerset), consent must be obtained from the relevant Drainage Board. Note that any activity within 9 metres of a watercourse in these areas requires Drainage Board consent.

If the watercourse is an ordinary watercourse outside a Drainage Board area and is not a Main River, consent must be granted by the local council.

WCI can advise on the correct consenting route for your project and assist with applications.

You are the legal operator of a private drainage system if you own the property that uses it – including where the system is shared with another property – or if your property deeds or tenancy agreement state that you are responsible for maintaining it.