Is Your Private Drainage System Compliant?
It is not uncommon to find that rural properties are served by private drainage systems, however, it can be uncommon for property owners to be aware that they must ensure that their system complies with current regulations, known as the General Binding Rules. If a system is not compliant, it can affect or delay the sale of a property. The most recent update to these rules was in October 2023.
There are different types of private drainage systems, but we find that there are two main types:
- Septic tanks
- Sewage treatment plants
The regulations apply to all systems, but septic tanks and sewage treatment plants are especially affected as they can involve discharging sewage or water into natural water courses or the environment in general.
Septic tanks:
A septic tank is used for the partial treatment of wastewater from properties that are not connected to a mains sewage system. It works by collecting wastewater from toilets and drains, and retains solids within the tank, while draining the water to (usually) a drainage field, if it is compliant with regulations. The tank itself is then emptied when necessary.
In the past, septic tanks have been known to drain into water courses which is what the regulations now protect against, as this was causing polluted water. Property owners were required to upgrade their systems before 2020 to ensure that they did not drain to a water course. It is surprising how many systems are still not complaint with the current regulations.
Any upgrade or replacement system has to comply with the regulations as well as the current British Standards. It also needs to be large enough for your purpose, which is based on the daily volume of waste discharged. A permit is required from the Environment Agency where a system discharges more than two cubic metres of wastewater per day. It is not unusual for property owners to not have the required permit, which can also cause delays when selling a property.
Since October 2023, it is not permitted to discharge using the same outlet as another property if the combined discharge is more than 2 cubic metres per day; and it is not permitted to have a system which is within 50 metres of another drainage system. This can cause issues if neighbours each have septic tanks.
Property owners upgrading their systems need to ensure that they have the relevant planning permission and building regulations approval to do so.
Sewage treatment plants:
Unlike septic tanks, sewage treatment plants are permitted to discharge into water courses. This is because they include a secondary treatment for waste, making it clean enough to discharge into the water, as well as to a drainage field.
A sewage treatment plant is subject to all of the same regulations as septic tanks (except for the above difference), must comply with the British Standards and have the relevant planning permission and building regulations approval.
Summary
In property transactions, it is always advisable for a buyer to carry out a specific survey to establish whether the drainage system is compliant with current regulations. If it is not, then it is generally a seller’s responsibility to ensure that this is rectified before completion of a sale. In practice, this can be, and is more often than not, dealt with by way of reduction to the sale price of a property, with the buyer confirming they will upgrade the system following purchase. Costs to upgrade a system differ from property to property, but it is said that upgrading a system can cost in the region of £20,000 (and it is not unusual for a sale price to be reduced by that amount), and so it is important for a seller to ensure that their system complies with current regulations before they agree a sale.