If your septic tank discharges into a watercourse (such as a ditch or stream) or does not drain into an appropriate infiltration system, it will fail to comply with General Binding Rules. As a result, you will need to replace it immediately. Failure to do so or improve the quality of wastewater discharged from your system may result in prosecution by the Environment Agency.
A sewage treatment plant operates similarly to other wastewater management systems, but with the addition of mechanical components that aid in breaking down harmful contaminants for a cleaner, safer, and more eco-friendly effluent. Wastewater enters the primary tank where the solids and liquids separate, with the remaining liquid then moving to a secondary tank. Here, a pump aerates the chamber, introducing additional oxygen to speed up the treatment process by encouraging friendly bacteria to grow and break down the contaminants and bacteria found in wastewater.
Domestic sewage treatment plants can reduce the polluting load in wastewater by over 95%, producing clear and odourless effluent. This level of treatment is typically sufficient to discharge effluent into a ditch, stream, or river.
To estimate your daily wastewater production, multiply your Minimum Population (P) by 150. For instance, if you have a three-bedroom house with a Minimum Population (P) of 5 individuals, your estimated daily wastewater production would be 750 litres per day (5 x 150).
When installing a septic tank or STP in a new location, full planning permission is typically required. However, replacing a tank with another or upgrading from a septic tank to a STP in the same position may not require planning permission. It is recommended to contact the local planning authority and provide a brief description of the proposal or submit a pre-application inquiry to clarify the need for planning permission.
Keeping your sewage treatment plant maintained is extremely important. This treatment plant should be emptied once a year by a registered waste carrier.
Overall, the average cost of buying and installing a domestic sewage treatment plant is around £7,000-£11,000. This is made up of the following broad costs.
If you are currently discharging wastewater directly into a watercourse or drainage ditch, installing a sewage treatment plant is essential. However, if your Septic Tank has failed but your drainage field is still functional, it is generally more cost-effective to replace the Septic Tank.
A drainage field, also known as a soakaway, is designed to spread partially-treated effluent over a larger area for further treatment. To avoid discharging wastewater directly from a septic tank into a watercourse it must pass through a drainage field. Alternatively, a sewage treatment system can connect to a drainage field if a watercourse is not available for discharge. The drainage field disperses the settled effluent safely into the ground for additional treatment. A porosity test can determine whether the ground receiving the water is suitable for drainage field installation.
On average, installing a sewage treatment plant takes between 5-8 days, though this may vary due to weather conditions and accessibility. Fortunately, you do not need to vacate the property during installation, and your daily routine will not be disrupted.
When a Soakaway fails, wastewater has nowhere to go, and the system will quickly back up, preventing any further wastewater from entering. Without prompt repairs, holding tanks will overflow, as will inspection chambers and open drain points. Any additional wastewater you add to the system will have nowhere to go, resulting in overflowing toilets, drains, and broken appliances, not to mention unpleasant odours.
