Water usage

One item not on the headline list is water usage reduction. By that I do not mean the heating of domestic hot water but overall water consumption. I suspect that the main reason for this is that the energy requirement for the supply and disposal of domestic water usage represents only a small fraction of the overall dwelling energy demand. Because of that it is not worth taking extraordinary measures to conserve and recycle water.

A typical daily per person water usage is around 150 litres.

There are many options available, from a simple lifestyle adjustment to ensure water is used in a considerate manner through water recycling and on to building a reed bed to purify waste water. These later options can be of great value if you are located off the beaten track and away from mains supply or drainage, but not when you are in a normal suburban setting.

An intermediate stage is the re-use of ‘grey water’. That is, for example, using the bath or shower water for toilet flushing. To do this at low power requires either solar electricity to pump the water or designing the locations, piping and storage so that gravity will do the work. Both methods involve intermediate holding tanks that require some management, cleaning and maintenance. Neither of these options applies in our bungalow refurbishment.

So the options open to us are….

  1. To reduce the flush volume of existing toilets to current recommended values.
  2. When replacing a toilet to install a dual flush toilet preferable with an ‘empty before refill’ cycle to minimise wash through.
  3. Install aerated shower heads to minimise shower water flow (typical reduction 20 % to 30 %).
  4. Minimise the use of bathing (preferring showering).
  5. When changing taps consider witting taps with a ‘water check’ function that provides a soft stop at an intermediate flow rate to encourage minimal usage.

For toilets, an old style single flush toilet can use up to 13 litres in one flush. Replacing that with a dual flush, modern unit can reduce the volume to four or six litres. Some models can get down to almost half of that. There are also conversion kits for existing toilets which claim that, by reducing your metered water usage, the payback is well under one year. Also water displacement devices that merely reduce the volume of water in the tank can be readily used; a brick for example!

The other are where water usage can be better managed is in the garden. Sprinklers use vast quantities of water and so should not be used. Plants that can survive reasonable dry spells should be preferred and any watering that is done should be done late in the day when evaporation is minimised. The water used should be conserved rainwater. Currently there is a small water butt collecting from the shed roof. But we do have a large area of flat roof that would be ideal for much larger gathering. To be investigated.


This list provides some direct links to further information. Where these are to specific products they are not recommendations, merely examples of the type.

Dual flush toilet retrofit device – http://www.ecobeta.com/products/Eco_Siphon_Oct08.pdf

Water saving toilets – http://www.lecico.co.uk/categories.php?cat=4


Combined washbasin & toilet (with water re-use) – http://www.roca.com.es/ww/index.html?en

Water displacement device – Hippo – A free hippo device – https://www.thameswater.co.uk/cps/rde/xchg/corp/hs.xsl/6672.htm

Bathroom tap with ‘Eco-click’ – http://www.bristan.com/epages/Bristan.sf/en_GB/?ObjectPath=/Shops/Bristan/Products/%22CAP%20EBAS%20C%22

Water butts for rain water collection – http://www.reuk.co.uk/Connecting-Water-Butts.htm

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