How to prevent backflow in the home

open hose pipe

Backflow prevention is crucial to keep domestic water hygienic and safe as it can cause detrimental issues. The horror stories of polluted water supply have been reported in the past and nobody likes hearing about how homeowners have found parasitic worms when running a bath. Therefore, preventing backflow is of paramount importance to the plumbing industry.

How does Backflow occur and what are its Common Issues?

Backflow can take place in both older and newer properties, and at building sites. In simple words, it is the term for the unwanted flow of water in the reverse direction. It happens due to back pressure and back siphonage. If backflow occurs and the mains water comes into contact with contaminated water, it can pollute the water supply to several homes.

Back pressure occurs when the pressure in the system is greater than in its supply, i.e. the system pressure has been increased by some means.

Back siphonage results from the supply pressure being lowered below that of the system; often taking place when the supply is interrupted or drained down.

Mains water is normally maintained at a pressure of 1 to 4 Bar, enabling it to flow from the tap or other such fixtures. This pressure also helps to prevent contamination of the mains water supply. The internal pressure prevents anything from entering the water system by ensuring that when a water outlet is opened, any contaminants get removed from the appliance. This allows us to carry out our daily tasks like showering, washing and using a garden hose safely.

However, it is when this pressure fails that backflow can happen. This can happen due to pipe bursts or when maintenance works are being carried out on the mains.

These situations can occur at building sites, care homes and domestic properties. One likely scenario of this happening is at homes with outside taps and hosepipes. When homeowners use a garden hose or a sprinkler system in their garden, backflow can occur if the hose is left on the ground. Any drop in water pressure can cause the supply system to ingest chemicals from fertilizers into the hose.

Double Check Valve

How to Prevent Backflow

Water Regulations in the UK state that a double check valve should be fitted in a position near the tap and after any other appliances or tees.

Double check valves allow water to flow only in one direction, therefore preventing the reverse flow of water and any harmful chemicals reaching the home. But how does the double check valve work?

It is comparable to the design of the human heart valve; it allows the flow of water through one way and closes if pressure comes back through.

Double check valves can be bought and fitted individually, but at JG Speedfit we have made them available as combination fittings, such as the JG Speedfit Isolation Valve and Double Check Valve.

Watch How to make a JG Speedfit standard push-fit fitting connection on YouTube.

Like other push-fit fittings offered by JG Speedfit, the Isolation Valve and the Double Check Valve can be installed and demounted within seconds in tight spaces, without the use of tools. For time-poor plumbers, this simple push-fit installation can reduce installation times by around 40% against traditional fixing methods.

Click here for a complete list of valves by JG Speedfit.

Other ways plumbers can help prevent backflow

Plumbers are well aware that stagnant water can freeze and burst the pipe. Therefore, it’s necessary to advise homeowners about the importance of isolating an outside tap during winter months. By isolating an outside tap the chances of bursting pipes can be minimised.

Older properties that have been constructed 30-40 years ago will often have stop taps instead of double check valves – that does not prevent backflow. When carrying out installations in such properties, it’s vital to discover if double check valves are installed.

It’s incredibly important to be on the lookout and be proactive about double check valves. They can cause a wide range of issues for homeowners and plumbers, so it’s best to be vigilant and be aware of how simple it can be to prevent backflow in a home.

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Richard Bateman

Product Marketing Manager Plumbing and Heating

About the author

A highly experienced and passionate professional, I have over 15 years' experience as a commercial and domestic plumber and hold NVQ Level 3 qualifications from City and Guilds

Since joining RWC in 2015, I began as a technical engineer, utilising my extensive knowledge to provide exceptional support. Currently, I am thrilled to be working with the marketing department as a Product Marketing Manager. 

This role allows me to combine my technical background with a keen eye for market trends, ensuring that RWC's products meet the evolving needs of the industry. With my wealth of experience and commitment to excellence, I am proud to serve as a spokesperson for RWC, sharing our innovative solutions and contributing to the growth of the plumbing and heating sector.