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The Base Guide to Energy Saving – Water



The Base Guide to Energy Saving – Water

As the cost of energy soars and climate change fears grow, what practical changes can you make to help you save money and help the environment?

Whether you have an existing property or are planning a new build or extension, there are actions you can take to reduce energy consumption. In the second part of this series, we look at how you can make the most of one of our most precious natural resources – water:


Water saving

Water shortages and poor water quality are increasingly making headlines – but did you know, a lot of the “waste” water that leaves your property could be reused?

Bathing, showering and even washing up uses huge quantities of water which, while not drinkable, could easily be reused for doing the laundry, flushing toilets or watering the garden.

Flushing toilets alone accounts for about a third of domestic clean water usage so, if you have a water meter, recycling could mean a huge reduction in your water bills – and you would be playing your part in making sure there is enough clean water to go round.

At its simplest, grey water recycling can mean nothing more difficult than taking your washing up bowl and pouring the used water down the toilet or onto the flower beds.

If you want to store the water to use later, though, some sort of water treatment will be needed to stop harmful bacteria growing on food debris, skin or hair cells or detergents. There are several options of varying complexity. All will need some degree of plumbing and pumping to recirculate the water through the filtration system and back to where it is to be used.

Sand filter method

This simple system uses a sand filter to catch any large particles before water passes through a soil box to clean it. The system uses gravity to move the water through the filter.

The top layer of the soil box is about 2ft of humus-rich topsoil, where most of the purification takes place thanks to organisms in the soil which feed and reproduce as the water passes through.

Next is a layer of very fine building sand, followed by a layer of coarse sand and a layer of pea-shingle for drainage. The sand filter method is suitable for grey water which doesn’t contain food debris.


The wetland method is also used for greywater with no food debris. The water is held close to the surface, which lets aquatic plants flourish. The water is treated with aerobic and anaerobic bacteria, with the roots of the plants also helping to speed up the treatment by absorbing dissolved organic material.

Septic tank

Grey water that contains food waste can be cleaned anaerobically in a septic tank before being filtered through the sand method as before.

Mechanical systems

These systems use pumps to divert water from bath plugholes, washing machines and the like to a storage tank, where it is treated with chlorine or a similar chemical. The system then pumps the water back to toilet cisterns, washing machines or garden irrigation systems as needed.

It is worth remembering that greywater, even treated, is not drinkable, and any water used to flush a toilet must be drained into the sewage system for proper treatment and not recycled further.

Grey water harvesting systems are easier to fit at new build or extension phase, but it is possible to retrofit to existing properties.

This Paragraph 84 (Paragraph 80 as was) home that we recently secured permission for will utilise grey water harvesting to minimise the home’s environmental impact.

A storage tank will be installed to collect grey water from kitchens and bathrooms as well as water draining from the driveway and hardstanding. This will then be stored and used for toilet flushing, garden irrigation and car washing. Any overflow from the storage tank will filter into two overflow ponds forming part of the site landscape.

Read part one – harnessing the power of the sun.


If you’d like advice on how to save energy and make your residential or commercial extension or build project more sustainable, get in touch!

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