Septic tanks a dirty word

When you are marvelling in the peace and tranquillity of having bought a home in the countryside, you are unlikely to find yourself in your new garden, enjoying the spring blossoms whilst considering the subject of sewage.  Although a dirty word, come 2020, ‘sewage’ will be at the forefront of the minds of most sellers and buyers of rural property. This is because, in 2020, all properties previously served by a septic tank that discharge into a river or stream will instead be required by law to install a sewage treatment plant at the cost of thousands of pounds.

The General Binding Rules, which came into force on 1 January 2015, state that if you have a septic tank that discharges direct to surface water, the system will need to be replaced or upgraded to a treatment system by 1 January 2020 or when you sell your property – whichever comes first.  A small treatment plant uses mechanical parts to aerate bacteria to treat liquid so it is clean enough to go into a ditch or stream. You will need to check that the treatment plant that you install complies with the British Standard BS EN 12566.

Treatment plants installed after 1 January 2015 require planning approval and building regulation approval. You also need to ascertain how much your system is discharging.   This can be calculated at  If you discharge more than 2,000 litres of treated sewage a day into the ground or 5,000 litres into flowing water, you will need a permit.

In the New Forest, most rural properties will not be on mains drainage and will therefore be served by a septic tank or treatment plant. As the New Forest is a designated sensitive area, any discharge will require a permit from the Environment Agency. New discharges to watercourses that seasonally dry up are not allowed under the general binding rules.

If you plan to buy a rural property your solicitor will need to raise detailed enquiries of the seller to ascertain the type of system installed and whether it complies with the new binding rules. If you are selling your property, you must inform the buyer in writing if you have a septic tank or small sewage treatment plant. Being able to provide potential buyers with records and a maintenance guide will provide reassurance that the system isn’t a liability.