With more and more douches being installed in UK households, Julie Spinks comments on the cross contamination issues that can occur and how this can be tackled

As illustrated in the WRAS Water Regulations Guide, every water system should contain adequate measures to prevent the backflow of fluid from any appliance, fitting or process from occurring into a wholesome water supply. Yet there are concerns that the increase of douches being installed to UK properties similarly increases the potential for backflow incidents. Click on image to enlarge.

Because of how douches are intended to be used and where they are located, there is a high risk of contamination to the drinking water supply. A douche is classed as a Fluid Category 5 – the highest possible risk level – which often means being fed from storage or alternatively must be protected from backflow by an appropriate device. The dangers posed by a douche are particularly acute if the hand shower is installed incorrectly. The length of hose often used to connect them to the mains supply means there is an additional risk of water from the toilet pan being siphoned back into the drinking water supply.

While douches have always been common across Continental Europe, recent years have seen them gain popularity in the UK. However, water regulations and fitting guidelines for douche installations in the UK are very different than across those on the continent – and if installers fail to adhere to the requirements there is a risk of drinking water being contaminated, putting customers’ health at risk.

The problem lies in the fact that many douche devices, typically installed in the bathroom or the en-suite, can reach below the spill over level of WC pans. Many of these devices are not being installed with adequate backflow prevention posing the risk of contaminated water getting back into the drinking water supply.

In order to prevent this, washing facility installations need to be fed independently to ensure the correct level of backflow prevention, (fluid category 5), which needs to be taken into consideration when designing and installing washing facilities of this kind.

Although douches can be inherently difficult to install to required standards, there are some simple tips to ensure requirements are met.

An independent supply pipe from a gravity fed cistern is often the easiest way to provide adequate backflow prevention, by means of a type AUK1 air gap arrangement. This can then be used to feed a dedicated water heater, where hot water is needed.

Alternatively using a pipe interrupter (Type DC device) will work as well, however the design practicalities can prove difficult and other problems may arise such as reduced water pressure and flow – so it is vital to give careful consideration before taking this route.

As a general rule, when installing these devices it is best to check the water supply arrangements the homeowner has in place already, to ensure the most appropriate solution is being used for optimised safety and regulatory compliance.

While douches are not the easiest device to install, their growing popularity does present a new revenue stream. However, for installers to truly tap into the market, it is vital that they do their research in order to ensure a safe and compliant method of installation, which can give peace of mind.

For further information please visit www.watersafe.org.uk.

Further resources for installing douches correctly and in accordance with the legal requirements are available at www.wras.co.uk.   

Julie Spinks is director at WaterSafe