This article will look at the main components of a rainwater harvesting system and hopefully demonstrate that even the smallest of properties will have room for one!
Storage Tank & Filter
The capacity of the storage tank will depend on how much roof area you have, and how much rainfall you get! Domestic tank sizes generally vary from 1500 litres to about 5000 litres, though could sometimes be up to 10,000L on very large properties. As a guide to how much space is required note that 1000 litres is equivalent to one cubic metre.
The tanks are usually sited below ground, and so can be placed under the garden area, or patio or driveway. If sited under a driveway, it would need to be protected from the extra weight of traffic, and make sure both tank and filter are supplied with a vehicle-loaded lid. The Wisy® vortex filters are rated at 30T GVW. (Gross Vehicle Weight) so are the most suitable for trafficked areas. With some tanks the filter is built in, so this is not an issue as long as the tank is vehicle rated.
There are different types of rainwater tanks – most are either GRP (fibreglass) or Polyethylene (plastic). Standard GRP ‘submarine’ tanks tend to require a slightly deeper excavation, but are cheaper than shallow-dig plastic tanks. However, shallow tanks can be useful where excavation is problematical, e.g. rocky ground, wet ground, etc. Site conditions and budget will determine the best type of tank to use.
How Much Space Is Required In The House?
The control units for most domestic harvesting systems will generally require a space of about 50cm x 50cm. Ideally, they can simply be fitted to a wall in the utility room or somewhere similar, or could even fit into the back of a standard kitchen cupboard.
The most important element of the control system is the pump controller; this is what makes sure that the pump switches on and off at the right time. Without this, the pump would have to be turned on / off manually or else the pump would run continuously. However, it is important to be aware of how much power the controller uses in standby mode (which is most of the time!) as many will continuously consume 10 watts or more. The controls must be sited indoors, in a dry frost-free location, and should be easy to access.
Do I Have To Have A Tank In My Loft?
No, not at all. In fact, many people prefer not to have a tank of water sitting in the loft, and some modern houses do not have a loft space. Also, most modern washing machines require mains pressure to operate. This means that the gravity feed from a header tank would need to be boosted by a second pump before it reached the machine.
However, if a header tank system is required, e.g. due to an unreliable power supply, it is possible to use small tanks with a mains water back up incorporated to save on space.
Is That All?
Yes! The submersible pump that supplies the system is situated out of the way in the outside tank. This means you don’t hear any noise when the pump is working. Also, a submersible pump gives better energy-efficiency as it is more efficient to push water than to suck it using a surface pump. The only other component that might be desirable (though not essential) is some form of tank gauge to check the level of rainwater in the tank – again this can be sited with the main controls.
In conclusion, the equipment needed for your rainwater harvesting system does not take up much space at all – in fact, you’ll hardly know it’s there!
Find out more by chatting to one of our team on 01452 772000, or by sending an email to . More information about rainwater harvesting systems, including design considerations, capacity and cost, can be found in our guide Everything You Need To Know About Choosing A Rainwater Harvesting System. Access a free download today by clicking here.