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A Guide to Harvesting Rainwater

Water feels like a luxury we take for granted. It comes through our taps and we don’t really have to understand where it comes from and how it gets to us. We just get to use it whenever we choose and pay for it when the bill comes through. The fact of the matter is, we are actually not as rich in water as you would expect from a rainy country like England and we should be much more aware of our water use as well as the process it goes through before it reaches us. Read on to understand water distribution in the UK and how you might want to consider harvesting your own water.

On average, each person in the UK uses 150 litres of water each day and this puts a strain on ponds, rivers and streams as well as the wildlife that relies on this water supply. The water we use is subjected to cleaning regulations, a process that uses a significant amount of carbon emissions. The only problem here is that only 50% of the water we use actually needs to be cleaned to this standard. Rainwater that falls in your garden can be used for toilet flushing, washing clothes, watering the garden or washing the car. By harvesting your own water you will not only ease the pressure on the national water supplies but you will reduce the demand for ‘clean’ water.

Water Harvesting

You have two options when it comes to harvesting your own rainwater:

  • Collect water in your garden and use it for watering your garden and washing the car.
  • Install a pump system that links your harvested water to your toilets and washing machine.

How to install?

Water harvesting is a very straightforward process where you direct the water from your drainpipes to a storage tank in your garden. It is an idea to bury your tank so it doesn’t look ugly in your garden and, in the more helpful sense, it stops frost getting to your tank.

If you decide to use the water for your toilets and washing machine then it will pass through a filter before it goes into your home. You will need a mains back up that intervenes when the storage tank runs out of water. You must also label and keep separate the plumbing for the system.

Is it right for me?

Renovations: When you install a rainwater harvesting system in your home it will require a lot of plumbing and digging in your garden to bury the tank. With this in mind it may be a good idea to try and include these changes when you are renovating your home, or, even better, when the house is built.

Water supply: You need to monitor the amount of water you get from your roof to see whether you will actually manage to collect that much water. Compare your findings with your water metre readings to see whether you will be able to produce 50% of your total water usage.

Toxins: if you have asbestos or another toxic material on your roof, you will not want to harvest your rainwater.

Garden only: You may decide that you want a tank to use only in the garden and for cleaning your car. This is especially helpful for those living in areas that regularly get hose-pipe bans.

What do I need?

If you decide that rainwater harvesting is an option for you then you need to research what size tank is best for you, and what the total cost will be to install the tank.

Tank size: Your tank needs to hold up to 20 days worth of water based on your individual home. You can do the maths from your water metre.

Cost: A high quality domestic system will cost between £2,000 and £3,000 and running the system will cost between 5 and 10p a week. For most homes it is a better idea to concentrate on reducing your water usage as opposed to installing a rainwater harvesting system. You probably won’t see a return on this investment for about 10 years whereas reducing your daily usage of water can save water and reduce carbon emissions in your home.

Commercial Rain Water Harvesting

Commercial buildings lend them themselves to collecting large amount of water due to large roof areas. There are specialist companies can help with consultancy and design.

Some typical usage of commercial / industrial rain water harvesting are:

  • Flushing a Toilet
  • Wash Down
  • Animal Feeding Troughs
  • Agricultural Sprayers
  • Irrigation Systems
  • Truck & Machine Wash Systems
  • Carwash Systems
  • Dairy Applications
  • Fire Fighting Systems

Do you have a water harvesting system in your garden? What do you use it for? How much of a different has it made to your life and your bills?

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