Rainwater can contribute to the water supply on dairy farms

Rainwater collection from roofs or other clean areas can make a significant contribution to water supply on dairy farms, says DairyCo extension officer, Chris Coxon.

“The average cost of water to a dairy farm is £31/cow/year,” he says. “With the average farmer using 10,000 litres/cow/year for just washing parlour walls and floors, the use of harvested rainwater can prove highly efficient.”

High rainfall areas offer more potential, but small volumes can contribute to vehicle, yard and parlour wall wash-down, as this water needs minimal filtering.

“However, for stock drinking water, water must be filtered and treated to avoid contamination,” Mr Coxon continues.

“It is also important to remember, dairy hygiene regulations require any water used for hand, udder or dairy plant washing to be from a potable source.”

Although filtering and storage comes with a significant cost, if you can use an inexpensive storage facility, such as a pond or tank, water harvesting can be a cost-effective option.

Check your local rainful data to see how valuable it might be. “You will need to calculate your roof area to get an idea of what is available for collection.”

“On average the amount that falls, reduces by 10-20% when collected mostly due to evaporation, so one cubic metre of rain will become 0.80-0.90 cubic metres once collected.”

“Work out how much you can afford to spend,” he says. “Consider potential contamination or the need for filtration or UV treatment.”

Also take into account running costs, and remember water still isn’t ‘free’ once you have paid off the capital cost, as the cost of disposing of dirty water ranges from £0.50-£1.50 per cubic metre.”

To order a copy of DairyCo’s booklet on Effective Use of Water on the dairy farm,call 02476 478695, or email publications@dairyco.org.uk.