Many allotment sites do not have the benefit of mains water. Rainwater harvesting and storage is the solution adopted by Elizabeth Way Allotments, Coventry. Many thanks to them for sending the information and photographs.
As their allotments never had access to running water, they decided to improve the situation and construct their first water station. The water station is additional to plot holders own water collection systems, used for emergency and dry spells though the summer months.
Even sites and gardeners with access to mains water would be well to consider installing an independent supply system. Whenever we get a hot, dry summer and need to water it seems a hosepipe ban is implemented. These bans only apply to mains water not that from your own storage.
Firstly, we would like to thank the Coventry City Council & CDA&G for their help and support with this project. The construction as you can see is wonderful for the environment, completely stand alone, can be constructed in any spare area on any allotment or perhaps smallholding.
The water harvesting station provides a cost effective and a wonderful addition to any allotment. This design is easy to erect, with a cost ranging from £500.00 to £1000.00 and can be erected by members with general handyman experience.Once constructed it comes with little maintenance and gives many years of free water.
Firstly they decided to install two strip concrete footings as their ground is unstable at certain times of the year. Next they constructed a timber frame to support the Perspex sheeting. This sloped down to a standard gutter system to supply the storage tanks below. The posts are seated in standard Drive-in Post Anchors.
I can see a potential problem with the design in high winds where the force would be upwards on the sheeting. It’s important that the sheets are properly fixed to the frame.
Storage is in four IBC containers. These standard sized – one metre cubed – containers are readily available second hand on Ebay at around £50.00. Look for “FOOD GRADE” containers to avoid any poison’s that were previously stored in the tanks possibly affecting the produce grown
Each container is able to hold 1,000 litres giving 4,000 litres when all four containers are full.
Placing the containers
The IBC containers need to be lifted from the ground to enable easy filling of watering cans etc. This is accomplished by mounting the containers on concrete blocks, three high. Use the high density blocks because they will have to carry a lot of weight. The builder’s merchant will point you to the right product. 1,000 litres of water weighs 1,000 kilograms plus the container weight.
It’s critical that the support is sturdy and stable as a collapse is potentially dangerous. Ensure the blocks are placed on a firm base. Do not use pallets to support the tanks. Over time the pallets will rot and collapse.
Filling Watering Cans
Hose union bib taps have been fitted to each unit, and each container has been fitted with small section of garden hose with the use of jubilee clip to cut down on the waste of water when in use. Each container is connected by the use of standard plastic waste pipe and fitting, all available from local plumbing merchants.
Keeping the water sweet
As rainwater enters the first container make sure that the hole put in top of tank to receive the water is a tight fit and sealed to avoid mosquito’s & larvae at a later date, always keep the top inspection lid in place to help avoid this problem.
It may be advisable to obtain black covers for the tanks to help with discolouration in water over time if funds allow. There are a number of inexpensive commercial products available to keep the water clear of insects, algae and bacteria such as legionella. See Keeping Water Clean & Safe