Dairy farmers invest heavily in feed, genetics, and technology to optimise milk production. But how often is drinking water critically examined? Remarkably, it turns out that there is regularly room for improvement. Poor water quality can unknowingly lead to lower production and health problems. It is therefore time to take water more seriously as a factor of production.
Thank you for reading this post, don't forget to subscribe!At a dairy farm, milk production was lagging. Every possible cause was investigated without yielding any results, until water quality was examined. Samples analysed by Royal GD showed that iron and manganese levels were too high. Further investigation revealed significant deposits of both minerals inside the water pipes. Consequently, the pipes were cleaned by a specialist company. Follow-up sampling showed that iron and manganese levels had fallen sharply. The farmer soon noticed that water intake and milk production had resumed their upward trend.
This practical example comes from zootechnical specialist Marion Veldman, a GD expert on water quality for cattle. She uses it to illustrate that water quality is often overlooked when cows experience health or production problems. According to Veldman, investigations into water quality on dairy farms frequently reveal abnormalities such as excessive iron and manganese levels, high bacterial counts, or water that is either too hard or too soft.
“Dairy farmers often only ask us for water advice during renovations or new construction, or when serious production or health problems arise in their cows. Yet we advise monitoring water quality once a year. The importance of good drinking water is quite often underestimated in practice,” she observes. And that is a shame. “Good drinking water is not an extra, but a basic requirement for healthy and productive cows.”
44% of samples unsatisfactory
Research by Royal GD showed that 44% of the water samples analysed in 2025 were rated less than good due to bacterial contamination. According to Jeroen Koks, Business Manager Water at GD, progress is visible. “Looking at the past 5 years, we see a clear improvement in water quality. Nevertheless, there is still room for improvement at nearly half of the farms,” he explains.
Drinking water is assessed for the presence of contaminants and certain substances, with scores ranging from good to moderate and abnormal. Of the samples examined, 56% scored good, 29% moderate, and 15% abnormal. The latter two categories are particularly concerning. With a moderate score, there is a risk that cows will produce less milk because their bodies must use energy to fight bacteria instead of for milk production. When water quality is rated as abnormal, this can even be directly harmful to the health of the animals.
On average, a cow needs 4 litres of water to produce 1 litre of milk. Veldman explains that even a small decrease in water intake can have major consequences. “When a cow drinks 5% less due to less palatable water, you see that reflected immediately in milk production. Drinking less leads not only to lower fluid intake, but also to lower feed intake and ultimately less milk.”
Between 120 and 200 litres of water per cow per day
Over the past few decades, the water intake of dairy cows has risen sharply due to an increase in production levels. In 1950, the average dairy cow produced 4,000 litres of milk per year. Now, that figure stands at nearly 9,500 litres per year. Consequently, a cow’s water requirement has increased significantly. The amount of water a cow needs per day nowadays depends on age and milk production, but also on the ambient temperature and humidity. For maintenance, a cow needs about 10% of her body weight. Furthermore, up to 3 to 5 litres of water are required to produce 1 litre of milk. A high-producing cow therefore quickly requires more than 150 litres of water per day, sometimes rising to as much as 200 litres per day. The importance of good drinking water quality is therefore essential.
Signals of poorer quality
According to Jeroen Koks, livestock farmers can easily pick up many signals about the quality of the drinking water themselves. “Pay close attention to how a cow drinks. Does she do so quickly and greedily, or rather hesitantly? That often says enough about the quality of the water.” A simple method is the so-called drinking glass test: “Scoop some water from the drinking trough, look at it, smell it, and taste it. If the water is not appealing to you, it probably won’t be for the cow either.”
Checking the water system between the source and the drinking trough can also reveal problems. Sagging pipes, dead ends where water stagnates, and insufficiently cleaned drinking troughs are common causes of reduced water quality. “Or copper couplings that wear out over time and dissolve in the water. And that copper eventually ends up in the drinking trough as well. So it is extremely important to monitor the water occasionally,” emphasises Veldman.
She recommends performing the GD drinking trough check once a year. This consists of a bacteriological and a chemical analysis. In the bacteriological analysis, the water is tested for manure contamination and the bacterial count. Additionally, chemical analysis is performed for substances such as iron, manganese, and nitrite. Livestock farmers can collect the water samples themselves and send them in. The cost for both analyses is €108.95. Additional testing for heavy metals and Salmonella can be included as part of the water analysis. The results can then be discussed with a veterinarian or feed advisor.
GD expects that dairy companies will increasingly mandate annual testing of drinking water quality. For example, this obligation already applies to participants in FrieslandCampina’s PlanetProof milk stream. Other laboratories also offer sample collection, such as Eurofins Agro. Research by Eurofins shows that the bacterial count in the drinking trough is regularly 25 times higher than at the source. Bacteria such as E. coli are also often present in much higher percentages in the drinking trough. Drinking water is classified as good if it contains fewer than 10 colony-forming units (CFU) per millilitre of E. coli bacteria. Ideally, the bacterial count, an indicator of overall hygiene in the barn, remains below 10,000 CFU per millilitre.
Cleaning pipes
Once contamination has been detected, the next step is to get the drinking water clean again. This begins with cleaning the water pipes to remove biofilm, limescale, and iron and manganese deposits. This is typically done using a combination of chemical cleaning and flushing. Specifically: first, the pipes are flushed with an acidic agent, such as 2% citric acid, to remove limescale, manganese, and iron. Next, an agent based on hydrogen peroxide or chlorine dioxide is dosed to kill biofilm and bacteria. After cleaning, the pipes are flushed with clean water to prevent the cows from ingesting the cleaning agent.
Another option is mechanical cleaning: by pulsating the application of water and air, the biofilm can detach and be removed from the pipes. Continuously adding a biodegradable disinfectant to the water is also a possibility. To maintain clean drinking water, GD and Eurofins recommend thoroughly cleaning the drinking troughs regularly in any case. There are various companies on the market offering services and products in the field of clean drinking water for cows. For example, there is the WaterSkid from MS Schippers, a fully automatic water purification system that purifies well water and tap water by removing calcium, iron, and manganese. Or the Watter system, which was developed to produce a disinfectant (HOCl) from salt and water on-site using electrolysis. This system claims to neutralise pathogenic bacteria, fungi, yeasts, and viruses in drinking water without the use of harmful chemicals.
Kanten Special Products BV offers various solutions for cleaning drinking water in cow barns, and 2 years ago, the company Remon introduced a completely new water purification system: the Titan UF ultrafiltration. This machine purifies surface water, recirculating water, and drainage water of suspended solids, clay particles, humus compounds, sludge, bacteria, and viruses. The end product is clean drinking water.
Tips for drinking in the pasture
Now that the grazing season is in full swing again, how do you ensure that sufficient, good-quality water is available in the pasture? Here are a few tips from GD:
- Ensure that the distance to the water troughs is not too great.
- Provide sufficient drinking spots: one drinking spot per 20 to 25 cows.
- Ensure easy access to water points.
- Create sufficient space around water points.
- Ensure that the water supply is adequate; a good capacity involves more than 15 litres of water per minute.
- Regularly test the water quality at the drinking spot. Shallow water sources more often have excessively high bacterial counts and chemical abnormalities.
- Ensure that no algae growth occurs in the water.
- Take timely measures during periods of heat stress, with the emphasis primarily on sufficient water points and sufficient available water.
- Regularly change the water in a deep water trough; this helps prevent algae growth.
Oxygen on the rise
Adding oxygen to drinking water for cows is a development that has been gaining popularity recently. GLB BV from Bodegraven (South Holland) has been marketing a product for this purpose for several years now: MetO2. This is a liquid oxygen that is slowly released into the drinking water in the barn.
Advisor Jobbe Laan explains how this works. “We measure, among other things, the so-called redox value. This value indicates the extent to which water can absorb and release oxygen. The optimal redox level in drinking water is approximately 260, whereas on many farms it is around 100. We then add oxygen to the drinking water, continuing until it reaches that 260 again. What we see then is that the oxidation level of the water increases. As a result, it is able to absorb and release many substances in the rumen. An additional benefit is that the water becomes fresher and more palatable. Cows drink more of it,” says Laan.
Another advantage is that the water also supplies the so-called facultative anaerobic bacteria in the cow’s rumen with extra oxygen. “They need this to function optimally as part of their role in keeping the rumen anaerobic.” This triggers various processes in the rumen, Laan explains. “The number of gram-positive bacteria decreases sharply, and that is beneficial because they produce ammonia and toxins 20 times faster.”
Availability and access
What about availability and accessibility? Barn equipment supplier Spinder advises dairy farmers not to place water troughs too high. For instance, a dairy farmer in Drenthe in the Netherlands immediately saw increased water intake after lowering the drinking trough. GD confirms this. “We sometimes see water troughs hanging 90 centimetres or even a bit higher. The argument is that cows defecate less in the trough. But our advice is really to hang a water trough at a minimum of 60 and a maximum of 70 centimetres; this best suits the cow’s natural posture,” says Veldman.
Kanters recommends a water pressure of at least 20 litres per minute per drinking point and at least one drinking place per 10 to 15 cows. “Because if a cow lower in rank is constantly pushed away, she will drink less. And that means lower feed intake, poorer rumen function, and lower milk production.”
Lely observes in practice that cows drink in short periods: 7 to 12 times a day, consuming between 10 and 20 litres of water each time. “Cows prefer to drink after milking and during feeding. This behaviour is clearly visible in herds where cows go to drink after visiting the milking robot,” according to the company. For open drinking troughs, Lely recommends a minimum circumference of 1.2 metres per 20 cows. The height of the trough should be around 60 to 70 centimetres, and the water depth at least 7 centimetres so that cows can fully submerge their snouts. The company advises that 10 to 15% of the herd should be able to drink simultaneously. Tap water or well water is preferred because it provides greater assurance of stable quality; this is less the case with surface water and ditch water.
Fresh water from ultraviolet C light
Killing bacteria in drinking water with UV-C light – this is the principle of Blue Watercare. This new system is being brought to market by Ebbers Metalworks in Doetinchem, the Netherlands. The water in the drinking trough is illuminated by a UV-C lamp, killing bacteria. There are two systems: one for cows and one for goats. “With the lamps, the entire bottom of the goat drinking trough is illuminated, allowing the UV-C light to expose settled feed and mucus residues. As a result, bacterial growth and biofilm simply cannot form,” explains director Helmer Ebbers.
In the system for dairy cattle, an air pump ensures continuous circulation of the water, increasing the oxygen level and ensuring the drinking water flows continuously past the lamp. The low-voltage lamps are located in the water, beneath a special rubber protective flap that ensures the livestock do not come into contact with the UV-C light. The system works without additives to the water, so it does not disrupt rumen function. “Our system is now running at dozens of livestock farms, and water quality is improving substantially at most farms,” says Ebbers. Water samples from troughs equipped with the system show bacterial counts below the GD standard of 10,000 CFU per ml, a standard he does not encounter in untreated troughs. It is suitable for virtually all open drinking troughs in cattle barns. Currently, Ebbers is focusing on practical experience within the Netherlands before the concept is rolled out internationally. The price for using the system with dairy cows is €975 per system, excluding installation costs.