There are around 800,000 homes in the UK that are not connected to mains sewage and many of those use septic tanks and drainage fields for wastewater treatment. Many people want to do what they can to protect the environment and this has led to an increase in the demand for sewage treatment systems. Also legislation that came into force on 01st January 2020 stipulates that systems must meet the General Binding rules resulting in the upgrade from septic tanks to package sewage treatment plants.
The quality of effluent from a package sewage treatment plant is much cleaner than that from a septic tank, but as yet there are no grants, government or otherwise, available in the UK to help meet the installation costs. It is not an area that has received grant assistance in the past and there are no plans to introduce grants in the future either.
When a house is not connected to the main sewer, it has to have a septic tank and drainage field, package sewage treatment plant (PSTP) or sealed cesspool, sometimes called a cesspit.
The most basic system is a cesspool, which is a large, sealed holding tank with only an inlet and a vented air outlet. It is designed to hold all sewage and waste effluent, it doesn’t carry out any treatment and there is no discharge from the tank. It can only be emptied via a suction tanker and so the annual running cost is very high. Cesspools tend to be installed in poor draining areas where a septic tank or treatment plant would not be suitable.
A septic tank will remove as much of the solids content from the final effluent as possible and a drainage field is then used to disperse the septic effluent. A domestic septic tank if sized correctly should only require a vacuum tanker desludge / empty once a year, installation costs may be from £6,000 and running costs are around £180 per year.
A package sewage treatment plant is the most expensive system to install, from £7,500, it uses natural biological aerobic action to treat sewage to a very clean level. Most package sewage treatment plants require a service at least once a year and this, combined with the electricity required to run the plant, will mean running costs of around £320 per annum. The discharge can be either to a drainage field or viable surface water outlet. The risk of damaging a drainage field will be reduced as a package sewage treatment plant’s discharge is so much cleaner than a septic tank.
A drainage field consists of a slotted pipe wrapped in a membrane and surrounded by stone and is used to disperse the effluent from a septic tank or sewage treatment plant into the ground. The cleaner the effluent discharge then the longer the life of the drainage field, which is why regular desludging and maintenance of the septic tank or package sewage treatment plant is essential.
If the property has a viable surface water outlet, an existing surface water drain or nearby watercourse, then a drainage field isn’t necessary if a package sewage treatment plant is installed as the effluent can discharge to an existing outlet. Legislation that came into force on 01st January 2020 stipulates that septic tanks that discharge to watercourses must be upgraded to package sewage treatment plants or connected to a drainage field.
How we can help?
Contact us on 01772 846193 / 07968 143756 or fill in the contact form if you have any wastewater queries or require advice. We can advise on the installation of new systems and carry out maintenance work on your drains, drainage field, pump chamber, septic tank or package sewage treatment plant.