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Rainwater Harvesting
Rain water harvesting for agriculture
Photo courtesy of E. Blenkhorn and Son, http://www.elderberrylimousins.co.uk

Rainwater Harvesting for Agriculture and Equestrian Purposes

There are a lot of farmers and equestrian enterprise owners who are shocked by the size of their water bills, bills that can be dramatically reduced by harvesting the biggest crop of all - Rainwater. Here at OASIS, we are all from a farming family background, with relatives who still farm the family farms and we have degrees in Agriculture. We fully understand the water requirements of the Farming industry.

Rainwater harvesting is the collection and use of rainwater falling onto buildings which would otherwise have gone down the drains, been lost through evaporation, or soaked into the ground. Buildings under construction present the ideal opportunity for rainwater recycling - or it can be added to existing buildings as a retrofit. (Photo courtesy of Elderberry Pedigree Limousin Cattle Breeders in Yorkshire - our M.D.'s brother.)

A harvesting system will involve diverting rainwater drainage to a rain water storage tank or reservoir to collect water and if necessary, could include treatment to improve water quality for specific uses. Distribution pumps and pipes may also be required to supply the water to where it is needed on-farm. There is a Rainwater harvesting system to suit all needs and budgets. 

It could simply be created by diverting roof gutters into a storage tank or water butt, or it could be more complex involving pumped storage, filters and UV treatment for use on ready-to-eat crops.

Pumps and pipes can be sized to provide more pressure and flow rate than maims supply, enabling crop sprayers to fill much faster.

How much water do you use

Mains water costs around £1 to £2/M3 at the moment and this figure is due to rise dramatically in the near future.

Example for a Dairy Farm

A dairy farm with a 100 cow herd, has an annual water use of 5,400 m3, approximating 3,700 m3 for drinking, 900 m3 for milk cooling, and 800 m3 for parlour washing.

The farm has a 2,000 m2 roof area, and is in an area of 800 mm annual rain and could therefore potentially harvest 1,600 m3 of rainwater. Some water will overflow the tank during very wet weather and some may be diverted as first flush from the roof. Assuming the farmer can store 80% of the 1,600 m3 of rainwater, i.e 1,280 m3, the potential saving on a water utility bill at £1.30 per cubic metre could be approximately £1664 per year using the harvested water for the parlour washing, or for animal drinking water. A Dairy farmer seeking a 4 year pay back could invest up to £6656 in water harvesting.

Example for an Equestrian Yard

A livery yard with 50 horses has an annual water use of 1200 M3, approximating 900 M3 for drinking, 36M3 for washing buckets, tack etc. 73 M3 for toilet flushing, 191 M3 for washing horses, boxes, hosing tendon injuries, etc.

The yard has a total roof area of 1700M3 and is in an area of 700mm annual rainfall. It can harvest around 1190 M3. Assuming storage of 80% of this water, i.e. 952 M3, this will more than supply the drinking water required and save around £1142 per year on mains water charges. 

All those uses listed above could be supplied with rainwater. With the large roof area provided by farm buildings, stables, barns and indoor schools, sufficient quantities of rainwater can be collected and stored for all uses that do not need human drinking quality water.

Above or below ground storage tanks

Above ground tanks are cheaper to install as there is no cost involved for digging a hole. However, underground tanks are to be recommended as the stored water stays fresh and cool if not above ground (bacteria do not form in temperatures under 12 C) so animals prefer it. It makes sense to put the tank underground, as tractors and implements cannot damage it.

The tank should be placed in the best location to collect rainwater from the downpipes. The rainwater is cleaned, either by a filter in the downpipe, or more normally, by a filter in the tank itself. These rainwater filters require very little maintenance and remove enough debris to make the water quite suitable for all those uses that don't need human drinking quality water.

A pump inside the storage tank takes the rainwater to where ever it is needed. The type of pump normally used can deliver up to 5 bar (household pressure is around 2.5-3.0 bar) or over 3000 litres an hour. It is certainly powerful enough to water an arena or other large area. If the pump is connected to a hose or tap, it will automatically start when this is turned on. 

Another essential feature needed is a reliable mains back up that will switch automatically to mains water if the storage tank runs out. OASIS will do a rainwater tank size calculation for you, this is worked out on the average rainfall for where you live, the roof area, and what you need the rainwater for. Normally, planning permission is not necessary. However, planners now often favour building applications that include rainwater harvesting. Official pressure is on to reduce mains water consumption on the one hand and also to alleviate flood threats. Rainwater harvesting helps with both these issues.

If you are a business, you can benefit from the Enhanced Capital Allowance scheme whereby 100% of material and installation costs of rainwater harvesting systems registered on Water Technology List can be offset against tax liability.

Rainwater harvesting is clearly of enormous benefit to both agricultural and equestrian enterprises. With such high water usage, the return on capital will be between 2 to 6 years. Let us size and design your specific rainwater harvesting system.

OASIS Rain Water Harvesting - Free Water From Nature

Oasis Rainwater Harvesting

Unit 2, Bolton House Farm, York YO41 5QX

Tel 01759 369915

Email james@wte-ltd.co.uk

Rainwater Harvesting Systems and Tanks from OASIS - HOME

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