Modern sewage treatment plants generally fall into one of three categories – bio disc, air operated and pumped systems. Although they are more sophisticated than some of the other non-mains drainage systems, including septic tanks and cess pits, treatment plants can and do break down occasionally.

Here Gilson Environmental Services, who provide sewage treatment plant maintenance services in Suffolk and across East Anglia, identify the three main types of treatment system, the commonest internal issues they can be affected by – and why we are the people to turn to if you ever have a problem.


The Commonest Types of Sewage Treatment Systems…

Disc Systems – Here a motor turns a chain or belt-driven sprocket attached to a shaft covered in plastic filter discs (or, in older models, fibreglass). When the shaft rotates it allows bacteria to grow on the discs.

The waste is treated in two separate zones, with only the treated effluent being allowed to leave the plant and enter the watercourse, soakaway or drainage field.

Air Operated Systems – These contain a probe which is directly connected to the effluent (it can either suck air up over the sewage, or blow air down onto it, depending on the type of system).

Pumped Treatment Systems – here a primary septic tank removes solids from the effluent before it enters the treatment plant. The effluent is then pumped up to the top of the system and runs over a plate or sprays onto the filter media where the bacteria grows. The treated effluent is then allowed to flow into the watercourse or drainage field. These systems normally stick out of the ground.


…and the Commonest Problems

Blockages – Sometimes parts of the system can be blocked. This may be caused by overloading – the treatment system simply isn’t big enough for all the wastewater and effluent going through it – or because a plant or tree root has penetrated some of the pipework. In the case of air operated systems, a filter may be blocked.

Some of these issues you may be able to rectify yourself by cutting down on your water usage or uprooting and removing your offending plants. When it comes to repairing blocked filters or broken pipes, you should call in the specialists like Gilson Environmental Services.

Electricity Supply Issues – A tripped circuit breaker or fault in the cable or wiring could mean that the air pump (in the case of pumped systems) or the blower (in air operated systems) won’t operate at all. Most treatment plants have an inbuilt alarm which should tell you if something is wrong; but if it is happening on a regular basis, it would again be best to get the experts to have a look at it.

Other Mechanical Issues – There are a number of other mechanical issues which can affect all types of sewage treatment plants, because of the mechanical parts which are involved. In the case of disc systems, belts can snap, and motors or gearboxes can fail; and In such cases you’ll need an emergency repair.

Incorrect Commissioning – This can apply to any type of sewage treatment plant (and other methods of waste disposal as well). Once any new system has been installed it will need commissioning. This means it has to meet the criteria set out by the original manufacturer. Once it has passed these, a certificate can be issued to show that it complies with the relevant Building Regulations. Failure to commission it correctly means the system could be more prone to breakdowns.

External Issues – Sometimes the fault isn’t with the treatment system itself, but the way you have been using it. For instance, if you notice a bad smell in and around your property, it may not be the fault of the treatment system; you may have been putting too much grease or oil down your sink, leading to a blockage or back-up of sewage. For more details, check out our previous blog post here.


Sewage Treatment Plant Maintenance in Suffolk from Gilson Environmental Services

Gilson Environmental Services are sewage treatment plant installers (as well as servicers) operating from our base in Ipswich. This means whether it’s an air operated, pumped or bio disc system, we will have the expertise – and the parts – to service or repair it. Email us at to learn more about our regular maintenance programmes which should reduce the risk of any breakdowns.

If there are any issues with the way your treatment plant has been installed, we always look to correct them on the spot to ensure you are left with a fully operational system.

We are truly independent, which means we are not tied to any particular brand or model. Among the manufacturers we are familiar with are leading names such as Klargester, Entec, Titan, Conder, Marsh, Vortex and Clearwater.

And if there’s an emergency, then we can deal with that too – just call us on 01473 741530.