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How To Use Harvested Rainwater For Livestock Drinking Water

Rainwater harvesting is bringing many opportunities in UK farming and agriculture that both reduce costs and improve sustainability. One of the lesser-discussed uses of harvested rainwater on farms is livestock drinking water.


Harvested rainwater is commonly used for machinery cleaning/parlour/building washdown, crop irrigation and spraying but also it can go further and be utilised as livestock drinking water.


According to the ADAS, dairy farmers in England spend an average of between £31 and £100 per cow per year on drinking water, with some livestock consuming up to 120 litres of water per day!


If harvested rainwater is used for watering livestock instead of mains water, farmers can reduce their mains water usage and benefit from a large reduction in water costs.


The Importance of Utilising Rainwater Harvesting in Farming


Drinking quality (potable or blue) mains water is a limited resource in the UK and due to the increasing energy costs for its treatment and transportation, the price of it is likely to continue to rise in the near future. Additionally, climate change may continue to cause an increase in droughts and water shortages.


This means that the use of rainwater harvesting is becoming increasingly necessary in the farming and agriculture industry whilst with the continued progression of technology, watering livestock with rainwater is now also a perfectly viable option.


The government is aware of the increased need for rainwater harvesting amongst farmers and landowners and has provided several grant options to help cover the costs, including the FETF grant and the Water Management Grant.


In addition, water quality is more controllable with harvested rainwater, whereas some on-farm water sources such as boreholes and wells may have water quality issues. On livestock farms, rainwater harvesting has the added benefit of reducing the risk of flooding during storms as well as the amount of dirty water that runs into slurry stores or water courses which can provide an additional reduction in running costs.




Initial Considerations Before Installing a Rainwater Harvesting System


To ensure you make the most of your space and get the best yield of rainwater, it is worth doing a bit of research first, which is also useful to determine your harvesting potential.

The first things to consider before investing in rainwater harvesting are:


- Local rainfall - in terms of quantity and frequency of rain, measured in mm per month/year


- The size of building(s) from which water can be harvested (this determines how much water you can harvest and the size of the tanks you will need)


- Roofing materials – while many are suitable, those that include materials such as asbestos, lead, zinc and bitumen can contaminate water and must not be used


- Requirements of livestock and percentage of the harvested water that can be used as drinking water


- Current water supply and costs which may be saved, including dirty water disposal


- Practicalities and cost of installing an efficient rainwater harvesting, storage and distribution system that also filters and treats the water appropriately for safe livestock watering (if this will be one of the uses of your system)


Is Harvested Rainwater Safe for Watering Livestock?


Despite common misconceptions, with the right treatment and storage, harvested rainwater is perfectly safe for all livestock and farm animals to drink, including cattle, pigs, sheep and poultry. In fact, many farmers find that livestock typically prefer drinking rainwater compared with mains water.


However, if rainwater is not treated and filtered appropriately, there are some risks that can be faced, so whilst it may initially seem unnecessary, it is important to treat the rainwater first to ensure its safety.


It is also worth considering that rainwater has no minerals in it, so livestock may require mineral supplementation as normal water mains supplies are likely to contain some minerals.


Improving Water Quality for Livestock


Here we will run through the necessary steps to take to mitigate those risks and improve the water quality to ensure the safety of livestock drinking water.


Step 1: Pre-tank Filtration


The first step to take to make rainwater safe for livestock to consume is filtering it to remove debris and bird droppings (which carry the risk of Salmonella) that collect on roofs.


At a minimum, a 2-stage filter will be required. The water cascades over the filter(s) and push it through the filter, leaving debris such as moss, leaves and twigs to fall into the soakaway. This works to avoid blockages and minimises the need for maintenance in the soakaway pipework.


Filter choice depends on if the tank being used has been installed above-ground or below-ground and most importantly the size of the roof area.


The following 2 stage filters are in 3 categories dependent on roof area 200, 450, 800 m2:


Zistern/Patronen Filter 200m2 - 2 Stage Filter


These can fit into the turret of an underground tank and can also be used in an above-ground tank set-up.


VF1/VF1 Combi Filter 450m2 - 2 Stage Filter


Essentially the same filter as above, but the VF1 is moulded slightly differently and suited to underground installation as all the pipework goes in and out horizontally.


These can also come with an extending riser for deeper installation depending on pipe levels in the ground.


Twin Filter 800m2 - 2 Stage Filter


Suited to larger rainwater harvesting projects.


Other Filter Types


For high-quality water, other filters such as sand filters or cartridge filters, can be used, but these are not generally required for livestock watering.


Step 2: UV treatment


In general, for watering cattle and sheep, harvested rainwater can be used without UV treatment. However, when water is stored for long periods or at higher temperatures (above 20°C), bacteria may be a concern and put livestock health at risk. In these cases, the rainwater may require additional filtering and treatment with an ultra-violet (UV) filter, which kills bacteria in well-filtered water.


Installing a UV filter which can cope with a heavy downpour will be expensive. One option for reducing costs may be to route the rainwater to an initial rainwater tank and then pump it through the UV filter at a suitable rate into a second water storage tank or direct it straight to livestock water troughs.



Table 1: Approximate Daily Water Requirements (AHDB)


Class of Livestock

Litres per day (drinking water)

Beef Cow (Dry)


Beef Cow (Lactating)


Fattening Cattle


Growing Cattle





Storing Harvested Water For Livestock


The rainwater tank capacity required depends on the frequency of local rainfall and requirements, i.e. Number of livestock to water and whether the water will be used for uses other than livestock watering.


Although we would suggest 2 to 3 months of storage for non-drinking spraying, irrigation and washdown purposes, typical livestock systems store up to around a week’s worth of water, relying on mains backup for periods without rainfall.


However, if the harvested rainwater will also be used for other uses, this will keep the water “turning over” allowing storage to be increased.


Above-ground vs Below-ground Tanks For Watering Livestock


Underground water storage is more expensive, but water remains cooler and at a constant temperature, so it is likely to keep fresh for longer. But water may need pumping out with an electric pump.


Above-ground water storage allows water troughs to be supplied by gravity. However, unless tanks are insulated or housed, water can heat up in summer, risking water quality problems through the build-up of potentially harmful bacteria. It is important to use corrosion-proof storage tanks (plastic), such as Enduramaxx water storage tanks or Paxton tanks, to avoid contaminating the water.


Example calculation of the costs and benefits? Livestock and Spraying

Example farm building (36mx15m) with a roof area of 540m2 in an area of 900mm annual rainfall. The annual amount of water falling on the roof would be 486m3, losses from evaporation and filtration will reduce yield by 15% to 413m3 per year of available water.


If the installation of a system costs £8,000 and this is spread over 10 years and maintenance is estimated at 2% of the installation costs/year, the annual cost would be £960 a year.


If all the 413m3 of water harvested can be used, the water would cost £2.32/m3.


The initial infrastructure is costly (filter/pump) but if there is the ability to increase the size of the system and utilise and harvest from other roof areas the system can be expanded at a far lower cost. This increases the number of uses for the harvested rainwater and self-sufficiency.


A beef unit finishing a total of 100 beef cattle over 300 days of the year, with a daily requirement of 30 litres a day, their annual requirement would be approx. 900m3. The 413m3 could provide approx. 138 days’ worth of water to the beef unit. For grazing units with minimal periods of housing, the system may need to be set up to feed both buildings and paddock troughs.


A typical wheat crop uses 750L/ha of water for purposes of spraying over a season (150L/application over 5 applications) (Bayer). Using the example above it has the ability to spray 550 hectares of wheat.




Rainwater harvesting has huge potential on farms because of the typically large areas of available space to site a system and large roof areas. This space can help farmers harvest a large amount of soft, neutral PH Water that can be used for various uses, one of which is livestock watering.


The cost-benefit will depend on the harvest potential, the type of livestock and the individual farm’s current supply costs.


Major considerations beyond practical installation considerations are the implications of using harvested rainwater on assurance scheme requirements, buyer’s contracts and insurance compliance.


However, rainwater harvesting in agriculture offers a sustainable solution on farms for increasing water supply and reducing run-off (slurry store capacity) issues, whatever the intended use, whether for washdown/spraying or going a step further and UV treating it to provide livestock drinking water.


Looking to Install a Rainwater Harvesting System For Livestock?


If you are looking to install a rainwater harvesting system in a farming or agricultural setting, we can supply a large selection of water storage tanks to customers throughout the UK. We stock Enduramaxx tanks and Paxton tanks and can also offer a rainwater harvesting installation service for farmers in the South West.


Browse our range of rainwater tanks and drop us a message or give us a call if you have any questions.






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