Who this affects
Many homes in North Oxfordshire are not on the mains sewer. This includes parts of Deddington, Hempton and Clifton, and the rural area around Shipston-on-Stour. These homes rely on a septic tank, a cesspool or a small treatment plant. The rules for such systems come from the Environment Agency, not from your water company, because they aim to protect streams and groundwater.
This guide explains the General Binding Rules in plain terms. It does not replace the Environment Agency's current guidance on gov.uk. However, it should help you ask the right questions.
What the rules cover
The rules apply to small sewage discharges from a single home or a small development, while larger ones need a permit. The treated water goes either to a soakaway or drainage field in the ground, or to a watercourse such as a ditch, stream or river.
If your system discharges to a soakaway and the field works, you can normally follow the rules without an individual permit. You must not cause pollution, and you must keep the system maintained. You must also stay within the volume limits.
Discharges to a watercourse
A watercourse is treated more strictly. A septic tank that discharges straight to a ditch or stream does not meet the rules. Since 1 January 2020, such a tank has had to be replaced or upgraded.
The usual answer is a packaged treatment plant that cleans the sewage first. The other route is to apply to the Environment Agency for an environmental permit. A cesspit is different again, since it stores everything and has no discharge at all.
When a house sale forces the issue
This point catches many people out. If you sell a home with a non-compliant tank, you must tell the buyer about it in writing. The tank still has to be replaced or upgraded, so the sale is when the problem comes to a head.
Conveyancing solicitors increasingly ask for proof of compliance before completion. As a result, a late discovery can delay a sale. If you are buying a rural home, find out early what the system is, where it discharges, and whether it complies. Our drainage checks before buying a rural property set this out step by step.
Repair or replace?
Not every septic tank problem means starting again, because many faults are small. We often see three common issues on off-mains homes near Deddington and Shipston-on-Stour:
- An undersized tank, often because the home was extended after the tank went in.
- A soakaway that has stopped working, usually because clay has sealed the soil or the site was poor.
- A sound tank that discharges to the wrong place, such as a ditch.
The last one is a compliance problem, not a performance one. Sometimes you can fix it by re-routing to a compliant soakaway instead of replacing the system, although the ground must suit it.
Ground conditions vary a lot, because ironstone, limestone and clay all drain differently. A soakaway that fails on one plot may work on the next. A percolation test on your own land is the only reliable guide to what a new system needs.
Know your system first
You cannot judge compliance until you know what you have, because each type has different rules. Our guide to septic tanks, cesspits and treatment plants shows how to tell them apart. Once you know, how often a septic tank needs emptying explains the upkeep that keeps you within the rules.
A camera check of the pipework helps in both cases, since hidden cracks are common. See what a CCTV drain survey costs and our drain survey guide for home buyers. For pipes that leave your land, read about whose drain it is under Thames Water rules.
Getting a straight answer
If you are unsure whether your system complies, our engineers can help, because we cover septic tank installation and repair, including compliance checks, across the Deddington service area and the Shipston-on-Stour service area. Request a quote online and we will advise honestly on what your system needs, even if the answer is nothing.
Our septic tank services page lists the work in full. Where the fault sits in the pipes, we also help with drain repairs in Southam and blocked drain help in Southam. While you are around Deddington, see blocked drains in Deddington and general plumbing in Deddington.
