Is Your Stock Getting Enough Water at Grass?
We have just experienced one of the driest springs on record, with rainfall in March and April typically 49% of the average UK annual rainfall from 1991 – 2020. Although the rain has come in recent weeks, before this there were concerns of water scarcity in areas. With plenty summer still ahead of us it is important to consider the risk of water scarcity due to prolonged dry, hot weather over the summer. Providing a clean, easily accessible water source when grazing livestock is essential. What you may not realise is the volume of water required by stock, with some dairy cows requiring up to 150 litres per day. The water provided must be clean, accessible and the systems able to cope during peak demand.
How Much Water is Required?
Water demand varies with temperature, grass dry matter, and whether the animals are lactating. The following table is a guide to recommended water requirements for stock. Note that some of this requirement will come from grass/feed and requirements will increase significantly with warmer temperatures.
Water Trough Location
Cattle generally spend most of their time grazing close to a water source. Troughs should be located near the centre of the field as this gives better utilisation of the whole field and should mean fields are more evenly grazed. Troughs should be positioned far enough away from fences to ensure 10% of the herd can drink at any one time. Ideally, troughs should be located under a hard base to reduce poaching and possibilities of subsidence over time. As a rule of thumb cows generally don’t like to walk more than 250 metres for a drink, so avoid cows having to walk long distances to the trough.
For those rotationally grazing, mobile drinkers are available. These allow more flexibility in paddock size and can help when transitioning to a paddock system to see where troughs are best placed. For paddock grazing it is advisable to locate the trough to serve multiple paddocks. A negative to this system is however water troughs cannot be plumbed into a mains supply, due to the potential risk of backflow.
Trough Cleanliness
It is crucial that livestock are supplied with clean water. Contaminated water (from faeces, feed dropped into troughs by cattle and other organic material) will reduce intakes as stock are likely to be put off by the taste and smell. Water troughs should be cleaned frequently to reduce the build-up of algae and reduce the risk of algae toxicity. Cleaning the trough can be as easy as removing the plug from the base and cleaning the sides with a brush or for those without plugs, a long day with a bucket. Before moving stock into a field ensure the trough is cleaned out if the field hasn’t been grazed recently. Water troughs in fields that have been shut up for silage that then return to grazing might need cleaning and water refreshed.
Managing water quality is not only important for intakes but to remove bacteria and the increased risk of diseases such as Leptospirosis, Johne’s and E. coli, all of which can be spread by water contamination.
When cleaning troughs check to ensure that ballcocks are working properly and that there are no leaks.
Water Flow Rate
An often-overlooked component of watering systems is the flow rate. A common problem is pipe sizes being too small which reduces the water flow rate. Pressure drop in water pipes is influenced by pipe length, pipe diameter, water flow rate, and elevation change (10 meters up/down equates to 1 bar of pressure (14 psi) lost or gained). Cows can drink at a rate of up to 14 litres per minute, creating high peak demand, which means without sufficient flow troughs can be left empty.
If a cow requires 104 litres of water per day at peak demand, a herd of 40 cows therefore require 4,200 litres per day. If this was consumed evenly throughout a 24-hour period, the water system would need to supply water at a flow rate of 2.9 l/minute (4200l/1440 minutes in 24 hours). However, this is not how cows behave as cows do not drink evenly throughout the day, and they often drink as a herd. To be prepared, the supply system should pump the required daily water within four hours.
Trough Size
The size of water trough should be big enough so that 10% of the herd can drink at one time to reduce stress and queueing. It is recommended that there is a minimum of 10cm of water trough space per cow. So, for example, for a 50-cow beef herd 5 cows should be able to drink at one time.
Key Take Home Messages
- Location – Ideally locate water troughs in the middle of fields to reduce poaching and away from watercourses to reduce the risk of run off. Where possible situate on a hard base.
- Cleanliness – Ensure water troughs are cleaned regularly and thoroughly. Supplying fresh, clean water will allow for better intakes and improved performance.
- Flow rate – Ensure the flow rate is adequate to supply the size of the trough and the number of animals.
- Size – Ensure that 10% of the herd have enough space around the trough to drink at any one time.
- Stock Types – Remember different classes of stock require varying volumes of water. Lactating cows have a greater requirement and water requirements for finishing cattle increases as live weight gain increases.
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Scott Murdoch, Consultant, Scott.Murdoch@sac.co.uk
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Posted by Unearthed News on 17/06/2025
