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The importance of clean water on farm and how to achieve it

Chris Gregory BVSc MRCVS

Provision of clean water on farm is often overlooked as one of the most important nutrients for the health and productivity of our livestock. As a gross simplification, about 65% of the mass of a cow is made up of water. It takes about 3 litres of water to produce 1 litre of milk, which is itself more than 80% water. Bearing that in mind, it stands to reason that the quality and cleanliness of the water we provide is a fundamental input to food production. 

Red Tractor standards define clean water as:

“…does not contain micro-organisms, harmful substances or toxic marine plankton capable of directly or indirectly affecting the health quality of food.”

Mains vs. Private Water Supplies

When discussing water quality, it is often assumed that mains water supplies are immune to problems. Rightly so, the supply of water to the farm should be potable, however issues often arise in how the water is stored or utilised after it arrives at the farm. Areas prone to contamination include:

  1. Water troughs.
  2. Mass storage tanks (e.g. volume washer).
  3. Warm water immersion heaters heating water to < 50°C (e.g. warm water parlour hoses).

Private water supplies are convenient and can often represent a significant cost saving but it is important that these are adequately maintained and monitored to ensure the water is consistently safe and clean. In accordance with Red Tractor, water supplies are required to be inspected/risk assessed annually, and a source sample tested at least every 2 years as a minimum (see Fig.1 taken from Red Tractor Standards).

Common problems with private water supplies:

  1. Contamination from run-off (e.g. after heavy rainfall/surface flooding).
  2. Livestock/vermin contamination at source.
  3. Variable mineral content (e.g. Iron/Manganese/Sulphur content).
Figure 1. Private water supply testing frequency. Taken directly from Red Tractor Dairy Standards.


Routine water testing checks for the presence of key indicator bacteria (E.coli & Coliforms) associated with harmful bacterial/faecal contamination. If the acceptable level is exceeded (10 CFU/100ml) then further testing is required to locate the source of the problem and fix it.

Whilst a level of 10 CFU/100ml or less is considered acceptable, we would recommend that any water used to wash parlour equipment, udders or plant should have zero E.coli/coliform bacterial counts.

Case Study

‘Farmer A’ had been reporting increased levels of mastitis in the herd. The mastitis cases were not responding to the normal treatment protocols. As a diligent farmer clean milk samples had been collected from some of the representative cases pre-treatment and submitted to the lab for culture.

8 out of the 14 samples submitted returned growth of Pseudomonas, a bacterium associated with dirty water sources.

The key water sources in the parlour were sampled; the volume washer and warm water drop hoses.

The volume washer hose proved all clear.

However, the warm water drop hoses cultured the same Pseudomonas bacteria associated with the mastitis samples.

In this case, the warm water had been sourced from an immersion heater in the dairy. A combination of low frequency use and water temperature <50°C had led to an accumulation of bacteria in the immersion chamber/hoses. Simply turning the hoses off stopped any further cases associated with Pseudomonas until the heater and hoses could be cleaned and water temperature addressed.

A Solution to Pollution?

Identifying a contaminated water source is the first step, dealing with the problem will inevitably require investment in cleansing and filtration. Common set-ups include one, or often a combination of:

  1. In-line UV filters
  2. Particulate filters
  3. Dosatron addition of antibacterial (e.g. Hypochlorite) or cleansing products
  4. Exchange filters (Iron/Manganese/Sulphur)
  5. Ab/adsorbent materials

To find out more about water testing, quality and hygiene, please contact Molecare Farm Vets by emailing [email protected]

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