As the coronavirus pandemic continues to sweep through the nation, the priority is to keep people safe and healthy in their homes, whilst also protecting the NHS by ensuring safe and uninterrupted functioning of our healthcare facilities.
In this respect, we must also keep our plumbing and heating systems healthy, as water is a crucial commodity. We need to ensure that the water entering our buildings is safe for consumption, whether it’s being used for washing hands, providing drinking water, or for sanitation purposes.
One key area for protecting our water supplies is backflow prevention, which ensures water hygiene in residential, commercial, healthcare and public buildings. In this blog, we’ll discuss what backflow is, how water supplies can be contaminated, the problems it can cause, how to prevent it and the legislation around the use of appropriate backflow prevention valves.
What is backflow?
Before we go any further, let’s first understand what backflow is. Under normal circumstances, the mains water supply in a building flows in one direction to feed outlets like taps or showers. However, when there is a big, instantaneous drop in pressure or a break in the mains water line, there’s a high risk of stagnant dirty water flowing or siphoning backwards and into the main water supply due to reduced mains water pressure. This is known as backflow or back-siphonage.
Why does backflow happen?
Backflow often occurs when the pressure in the mains water line significantly drops. In most modern plumbing systems, the mains water supply is maintained at a considerably high pressure to ensure desired flow from outlets. In the event this pressure ‘drops’ – for example if a water main in the road bursts/ or a distribution pump cuts out – the water will rush back down to the break in the water mains pipe or the source of the water supply, causing a vacuum effect.
Under these circumstances, outlets served by mains supply can suffer a backflow effect, possibly allowing dangerous contaminants into the water mains. An example of a high-risk area could be a shower head left in stagnant bath water, which could allow the dirty bath water to flow backwards and contaminate the entire water supply.
How can you prevent backflow?
Backflow can be prevented through backflow prevention valves, such as a double check valve or single check valve. These valves allow water to flow only in one direction, hence preventing backflow and contamination of water supplies from external sources, such as wastewater in washing machines and dishwashers, or hosepipes that are submerged in garden ponds.
Choosing the right backflow prevention valve
To ensure backflow incidents are prevented and to safeguard our mains water supplies from potential contaminants, it’s essential that appropriate backflow prevention valves are installed in buildings. To do this, installers and specifiers must fully consider the fluid category that the installation fits into. These fluid categories are defined as follows by the Water Regulations Advisory Scheme (WRAS):
- Fluid category 1 – wholesome water complying with the requirements made under section 67 of the Water Industry Act 1991. There is no action required here.
- Fluid category 2 – water in fluid category 1 whose aesthetic quality is impaired by a change in temperature and/or the presence of substances/organisms causing a change in taste, odour or appearance. The use of single check valves is required here.
- Fluid category 3 – fluid which represents a slight health hazard because of the concentration of substances of low toxicity. The use of double check valves is required here.
- Fluid category 4 – fluid which represents a significant health hazard because of the concentration of toxic substances. The use of Reduced Pressure Zone (RPZ) valves is required here, and the commissioning and testing of these valves must only be carried out by an accredited tester approved by the local water supplier.
- Fluid category 5 – fluid which represents a serious health hazard because of the concentration of pathogenic organisms, radioactive or very toxic substances. A Class 5 backflow prevention device is required here, which will incorporate a Type AB air gap or equivalent.
Installers working in domestic properties will need to handle fluid categories one to three and those working in commercial buildings will experience all five categories.
Preventing backflow in a domestic environment
In domestic plumbing applications, best practice is to install a double check valve next to outlets that are more prone to backflow accidents. This type of valve features two internal valves to provide additional safety. If one valve fails, the other can still prevent backflow and potential contamination of the mains water supply.
The UK’s Water Regulations state that a double check valve should be fitted near taps and after any other appliances or tees, and the valve you choose must be compliant with the Water Supply Regulations 1999.
RWC’s family of brands offer a whole host of double check valves, each with unique benefits. For example, the JG Speedfit range of plastic push-fit fittings offers a Double Check Valve with a Stop Valve that includes a handy stop valve which isolates the water supply to specific outlets, allowing you to easily carry out servicing and maintenance work without having to shut off the whole building’s water supply.
For plumbers working in areas where a metal system is preferred, alternative options such as the SharkBite Double Check Valve featuring our brass push-fit technology is ideal, as it allows for a fast, secure and solder-free connection.
While, some white appliances such as washing machines and dishwashers may require single check valves that comply with the WRAS regulation. And this is where as our WRAS approved Floguard Single Check Valves manufactured from DZR brass are most suitable.
Preventing backflow in commercial buildings
In environments such as restaurant kitchens or hotels, it is vital that the appropriate commercial backflow prevention devices are used, as there is a greater risk of health hazards due to the type of fluids found in these buildings. Backflow incidents in commercial properties can result in the building being immediately shut down until the system is drained, and safe supply of water is guaranteed.
For the ultimate peace of mind, Reliance Valves’ Reduced Pressure Zone (RPZ) valve is one of the safest and most reliable backflow preventers available for commercial (fluid category 4 risk) applications.
This device is a verifiable check valve assembly that is designed to be regularly tested, to ensure that the risk of potential contamination is limited. In the event of a drop in pressure or back-siphonage, the mains water supply is protected by diverting the back-fed water from a property out to a waste pipe, therefore protecting the mains and drinking water supply and limiting the chances of contamination.
Protect our water supplies, protect our NHS
During times of crisis when our NHS is under immense pressure, it’s vital that every effort is made to ensure that our healthcare system keeps running as smoothly as possible. Contamination in water mains can cause disruption in supplying water to critical areas in hospitals such as surgery wards, intensive care units and patient rooms.
It is important to know where backflow can happen, so adequate preventive measures are put in place. A contaminated water supply can also lead to major disruption in the functioning of an entire community till the storage reservoirs are cleaned.
By protecting our water supplies, we can protect our NHS and ensure smooth functioning of our healthcare facilities. At RWC, we’re with you all the way, from technical support to help you source a complete range of reliable, quality approved backflow prevention devices to suit any application.
For the problem solvers, the urgent fixers, the everyday heroes and the truly up against it, we’re with you all the way.