10 Benefits of Waste Water Heat Recovery

Waste water heat recovery systems can save you money. If you are a self-builder they can help you reach CFSH Code 3 and they are Green Deal approved.

waste water recovery systems will re-use shower water

Waste water heat recovery is a relatively new way to reduce your domestic hot water load, cut CO2 emissions and save you money.  Until recently most CO2 savings in a home are focused on reducing space-heating loads.  This was done with low or zero carbon technologies.

However, these have been tested to their limits, especially on builds/ sites with small spaces.  But there is another way to reduce CO2 emissions from your home.  By reducing your domestic hot water loads.

Did you know that your domestic hot water use could amount to 49% of your total heat load (large detached house)?   This figure rises to 77% for a small mid floor flat.  Waster water heat recovery technologies have the potential to save you money.


What is waste water heat recovery?

A waste water system will recover the heat from your shower or bath by running your waste water through a heat exchanger.  This waste heat is then transferred to the cold feed to your combi-boiler (or cylinder), and then through the cold feed to your shower.  This pre-warms the water.

 10 Benefits of Waste Water Heat Recovery 400x420 10 Benefits of Waste Water Heat Recovery

10 benefits of waste water heat recovery

Here they are. The 10 benefits to installing a water heat recovery system.

1 They reclaim up to 60% of the heat you normally lose down the drain

2 They save you money on your heating bills

3 They work year round

4 They are very easy and quick to install

5 They are undetectable once installed

6 No maintenance is needed

7 They have no moving parts

8 High SAP points that can improve a new build by 5-8% (in line with revisions to part L of building regulations for 2014)

9 Will help a new build achieve CFSH code 3

10 Green deal approved


Key considerations:

Although there are great benefits to installing a waste water heat recovery system, to really get the best you need to follow some general rules.

  • To maximise your benefits heat should be removed from all showers in your home
  • The most effective systems feed pre-warmed water to both the shower and your boiler
  • You should choose a system with a high heat exchange
  • Most systems need a cold water pressure of at least 1.5bar
  • Make sure you look for the WRAS logo (so that the system complies with water regulations authority scheme)

The average price for a single unit is around £400.  Installing a waste water system should be a last resort to reducing your domestic hot water load.  You will be better off by using less in the first place than by re-using what you do.


Image: Steven Depolo

post your comment




One of the most effective ways to encourage wildlife into your garden is by introducing a pond. This guide will show you how to build a pond which your local wildlife will thank you for!

how to build a pond

Here's just a few useful and fun ways you can use the shells of pistachios and other nuts instead of throwing them away

pistachio shells

Find out how to keep your sugar intake low and avoid health problems such as joint inflammation and heart disease


Patagonia's unique approach to revealing information on their manufacturing process is something all aspiring green businesses could take a tip from.