What is backflow and back pressure?

Backflow is where the water flows back towards the supply source, either by siphonic action (back siphonage) or forced back under pressure (back pressure). This could be from taps, hoses or other water carrying equipment. Where water comes into contact with materials, chemicals or other fluids, these too could be ‘pulled back’ with the water and potentially contaminate your drinking water system.

Whatever the potential source of contamination, the water we supply to our customers must be protected. For this reason the Regulations require adequate protection to be built in and/or installed to prevent backflow from occurring. The Regulations place potential contaminants and substances into one of five fluid categories dependant on the harm it may cause. It also specifies the types of devices for preventing backflow that may be used and the fluid categories they are able to protect against.

How do I know what protection device I need?

When you understand what your risks are, it is easy to work out what level of protection you need.

For mobile users, swipe ← left / right →

Fluid category Description Example Prevention
(examples)

1

Wholesome water supplied by your water company United Utilities None needed

2

Water with a slight change of temperature, taste or odour
  • Ice machine
  • Fire sprinkler systems (without antifreeze)
  • Water cooled air conditioning united (without additives)
Single Check Valve (Type EC)

3

Fluid which represents a slight health hazard
  • Drink vending machines in which ingredients or carbon dioxide are injected
  • Washbasins, baths, showers
  • Commercial water softeners
Double Check Valve

4

Fluid which represents a significant health hazard
  • Dairies
  • Food preparation
  • Brewery and distillation plant
  • Commercial boiler top-up system
RPZ Valve (Type BA device)

5

Fluid which represents a serious health hazard
  • Gray water recycling systems
  • Medical or dental equipment
  • Vegetable washing
  • Sewage treatment, including sewer and drain cleaning
  • Water for agricultural use
  • Commercial washing machines
AA or AB Air Gap

Important Notice

Cold Weather

After a few freezing cold days in the North West, it looks like the temperature is beginning to rise.

As the weather warms up over the next few days, any frozen pipes in your home will begin to thaw. When this happens, some of your pipes may leak or burst. It's worth taking some steps now to be prepared just in case this happens to you.

  1. Check your pipes in any cold places such as the loft or garage - can you spot any water dripping from the pipe?
  2. Find your stop tap, which is usually under the kitchen sink and turn it clockwise to turn off the water.
  3. Turn off your heating, open all your taps to drain the system quickly.
  4. Soak up any escaping water with towels.
  5. Check with your home insurance company to see if you’re covered for leaks and bursts or call a plumber.
  6. If you need to find a plumber in your area visit www.watersafe.org.uk
  7. If water has leaked near your electrics switch them off at the mains.

For more help and advice if you have a frozen or burst pipe head to www.unitedutilities.com/winter.

Please think about your family, friends or any vulnerable neighbours and share this information with them too.

As the weather warms up, any frozen pipes in your home will begin to thaw. When this happens, some of your pipes may leak or burst. For more help and advice if you have a frozen or burst pipe head to www.unitedutilities.com/winter. Please think about your family, friends or any vulnerable neighbours and share this information with them too.

Cold Weather

Please click the button below to confirm you have seen this message

I have read this info