Rainwater harvesting – it’s not rocket science!Monday 14 May 2012
Given the recent high rainfall in Lancashire it was most fitting that our latest demo event concentrated on making more of this free natural resource through rainwater harvesting.
Our hosts for the day were Simon Stott and his family at Laund Farm, Chipping and the visit incorporated a look at the system they currently have in place on the farm to collect some of the rain that falls so frequently in this part of the world.
Twenty eight farmers attended the event to hear from a variety of speakers all focussing on making the most of water and looking at alternative sources as a means of reducing reliance on expensive mains water. The first speaker taking to the floor was Martyn Silgram from ADAS. Martyn has been working on a Defra funded project recently looking into different sustainable water systems for livestock and the relative costs of each.
Livestock need water
One high yielding lactating dairy cow requires up to 120 litres of water each day, which when you add it up across a whole herd is a lot of water (and a lot of money!). When the cows are housed this water must be provided to them, but out in the field there are other options available to supply water.
Livestock can drink directly from watercourses, however there are the associated environmental problems including soil compaction, erosion to the banks and pollution of water due to excreta. In addition to this are the associated health problems such as water transmitted infections and in the worst case scenario drowning!
Alternative ways of supplying water
The use of remote pasture water systems can help to avoid these problems as watercourses can be fenced off. Alternative water sources also increase the resilience of farmers to be able to cope with droughts and water shortages, as well as reducing reliance on expensive mains water (mains water costing in the region of £1.50/m3). The different options available are:
c)Solar (PV) pumps
All of the systems described above cost out as being cheaper than mains water but there are a number of factors to consider when deciding which system is best for you:
- Type and location of available water
- Site location and conditions
- Number and type of stock and their water requirements
- Access to power
- Pumping system
- Flexibility, reliability and maintenance
- Cost benefit and cost per animal
Dale Gibbons from the Environment Agency then gave a short presentation about the legislation surrounding water resources and abstraction licences. The Water Framework Directive is the specific piece of legislation which determines how we manage rivers and water pollution.
If you are planning any form of water abstraction, be it from a stream or river or a borehole, Dale recommended that you contact your local Environment Agency officer to let them know what you are planning so that they are aware of it. If that particular catchment area has a limited availability of water then you may not be granted permission to abstract water.
An abstraction licence only needs to be obtained if you are planning to extract more than 20 m3 of water/day. This amount of water is sufficient for 133 people, 173 dairy cows or 100,000 chickens! An abstraction licence will cost £135 in the first instance plus an annual subscription fee based on how much water you are abstracting.
If you are thinking of installing a borehole it is essential that you have the relevant geological surveys and ground assessments carried out first to determine whether or not your land is suitable and whether any drilling may be a cause of pollution.
Rainwater harvesting at Laund Farm
Following a wonderful lunch provided by the hosts we had a look outside at the system Simon uses for collecting and storing rainwater. Rainwater is collected by gutters from the roofs of three large buildings and stored in a 5,000 gallon underground tank to be used for washing down yards and the milking parlour. Water can also be diverted for filling sprayers or tanks for drain jetting. During the heavy rainfall on the previous Sunday six 1000 litre IBC tanks were filled during the day which just goes to show how much water potentially can be collected! The system is extremely simple and only cost in the region of £100 for the piping, with a tank already on the farm being used for storage.
Treatment of water
The issue of water treatment to make it suitable for livestock drinking was discussed as many of the farmers were concerned over potential health issues associated with livestock drinking untreated water. Barrie Jackson of Receau Consulting advised that the collected water is first filtered to remove any debris such as twigs or leaves before it enters the storage tank. When the stored water is pumped out of the tank it should be drawn through a finer mesh filter which will draw clean water from just below the surface. At this stage the water is clean enough to be used for washing and other non potable uses. If the water is required for drinking secondary filtration is needed and the incorporation of a UV filter which will kill 99.9% of the bacteria.
Simple and inexpensive
Barrie commented that the simple, practical system of harvesting rainwater employed at Laund Farm proved how straightforward it is to set up on any farm. Even if the water is only used to clean yards and concrete with surely this is much more sensible and cost effective than using drinking quality water for this purpose. Simple systems are inexpensive to set up – it is only when you get into the realms of treating water for drinking that the filtration and treatment becomes more complex and costly.
1) Check for any leaks - if your meter is running at times of very low water use it may indicate a leak somewhere.
2) Re-use any water where possible - water from the plate cooler can be reused in water troughs for drinking, whilst milking plant and bulk tank washings can be used again for washing down yards. There is a double saving here as the water is only being bought once instead of twice and you also save on the cost of disposing of dirty water (which can be between 50p and £1.50 per m3).
3) Do not over-use hosepipes - only use the hosepipe for washing down for as long as necessary and ensure that the pipe used is suited to the task eg. using a volume washer to clean the outside of a cluster is far less effective than a standard hosepipe at removing muck and uses far more water – more power is not necessarily better!
Andy then spoke about the grants which are currently available through the FFIS for funding towards rainwater harvesting equipment.