Thousands of properties throughout the UK currently rely on cesspools, septic tanks and domestic sewage treatment plants for the treatment of their waste water. The simplest form of off-grid sewage storage is by use of a cesspool (also known as a cesspit). This is simply an underground container which stores all the waste material until it can be removed in a suitable manner. The high level of servicing and maintenance required by these installations relative to their utility make them a poor choice in many instances.
Often a better choice than a cesspool, a septic tank is usually an underground installation which traps solids and allows them to break down, while allowing liquids to escape into a soakaway. For some applications, above-ground septic tanks are preferable as the don’t require planning permission.
The gold standard in household sewage treatment systems are mechanical domestic sewage treatment plants from companies like Clearwater. These work by pumping air through the accumulated waste to allow the resident bacteria to decompose the material more effectively. The result is that the effluent from a mechanical sewage treatment plant system is much cleaner than that from a traditional septic tank – possibly up to 95% clean water – and is therefore better for the environment. One of the critical measurements associated with wastewater treatment is B.O.D, which stands for Biochemical Oxygen Demand. This value is defined as the amount of oxygen required to break down biological molecules in sewage into carbon dioxide and water, and is usually measured over a twenty four hour or five day period. B.O.D. figures for Clearwater products are available here.
ASAP Septic Tanks offer Clearwater sewage treatment systems which comply with European Performance Standard EN-12566, which means they are approved for exemption from a permit to discharge under EPP2 environmental legislation. However, this does not automatically guarantee that if you install one of these units, you will not need a permit; you must also follow the General Binding Rules, which cover factors such as what materials are included in the sewage, what activities they are produced by, and the environment into which the effluent will be discharged. In all cases you must ensure your system is maintained as per the manufacturers direction and that the maintenance is carried out by someone who has the appropriate expertise to do it. You must also make sure that anyone who removes waste from the system is a licenced waste carrier. The General Binding Rules can be found in full, along with other information and guidance, on the Environment Agency website. If you live in Scotland, the equivalent body is the Scottish Environment Protection Agency (SEPA). It may also be advisable to liaise with your local water authority (for Nottinghamshire this is Severn Trent Water Ltd; their regulatory body is Ofwat).
Property developers should also note that if they intend to install any such system on a property which is close to existing mains sewage infrastructure, they will have to show a good reason why the building cannot be connected to the main sewer. The relevant distance depends on the number of properties which will form part of the development.
This is a complex and ever-evolving matter, so unless you are already familiar with the issues surrounding the siting and usage of residential sewage treatment systems, it would be wise to contact ASAP Septic Tanks directly to discuss your particular situation. It’s always best to make an informed decision.
Besides the above products, ASAP Septic Tanks also supply and install silt traps for drainage, bypass separators, domestic grease traps, waste water separators and many other related products and services. Anyone wondering how much home sewage treatment systems cost can find representative information here and here.