Pool Backwash

Swimming pool water contains a range of water treatment products such as chlorine, salt and acid, and filtration media (sand, diatomaceous earth). It also contains dirt particles (sediments), wind blown materials such as leaves and lawn cuttings, as well as body oils, sunscreen residuals and potentially harmful bacteria. In the normal operation of swimming pools, the filtration system collects these materials and captures/contains them in the filter. To work efficiently, swimming pool filters need to be cleaned by backwashing all the captured materials out of the filter. Backwash water from swimming pools has to be discharged responsibly. It also has to be discharged within the boundary of your property. By far the safest and most practical way to do this is by backwashing straight into a soakwell.

It is illegal to put inappropriate materials and substances down toilets, sinks and gullies and to connect swimming pool backwash, stormwater pipes and drains to the wastewater system. Children’s toys, bathroom rubbish, cooking oils and grease can cause wastewater blockages and overflows, as can debris from a pool filter. Some people occasionally backwash onto their garden, however if a pool is salt chlorinated, then any garden areas used for disposal would need salt tolerant plant species, otherwise they simply wouldn't survive. All in all the safest and most environmentally way to backwash your pool, is by using a pool backwash soakwell, or two or three soakwells for larger pools.

Concrete soakwells used as a backwash

The ideal backwash system will incorporate two 900 x 600 concrete soakwells linked together. For larger pools we would use two 900 x 900 concrete soakwells, and a combination of both sizes for medium sized pools. An example photo is below. As you can see from the example, the soakwells are linked together, and the pipework is directed into both soakwells, so that they fill simultaneously. The soakwells don't need to be located near to your pool, indeed they can be located anywhere within the boundary of your property, all we do then is extend the open end of the pipe to wherever your backwash valve is located. This pipe then comes up above ground to leave approximately half a metre of 90 mm pipe visible with a screw capped top on it, then every time you need to backwash, you simply remove the cap, and backwash straight into the above ground pipe, to take the water straight to your soakwells.

Upvc soakwells used as a backwash

Often in many cases it is not possible to bring in medium sized concrete soakwells to the rear of a property, in many cases access to established properties is limited due to the presence of walls, fences, plants, trees, even washing lines, that are concreted into the ground. In these cases, we use reinforced upvc soakwells linked together (for more details see the upvc soakwell page) This gives us the option to custom build a backwash system to cope exactly with the amount of water that will be washed into it. In most cases this involves using several soakwells in a row, all linked together, all with soakwell socks, and all set on a bed of blue metal to allow additional drainage. Below is a system we installed for a small pool, using three reinforced upvc soakwells linked together.

The Law

Please note the two laws below, before deciding to backwash your pool, without a soakwell system.

Section 25 of the Environment Protection Act 1993, General environmental duty — (1) a person must not undertake an activity that pollutes, or might pollute the environment unless the person takes all reasonable and practicable measures to prevent or minimise any resulting environmental harm.

Section 18 of the Public and Environmental Health Act 1987, Discharge of wastes in a public place — (1) A person who discharges waste into a public place is guilty of an offence.

People can often be seen discharging water from their backwash system over a wall or fence onto parkland, or onto an empty lot. This is an offence. It is also an offence to discharge your water onto somebody elses property, or on to a roof of a neighbour, that may have a house much lower than yours, again this is an offence.