Quality of drinking water
Water is an animal’s primary nutrient. For this reason it is essential to ensure a sufficient supply in both quantity and quality. Having water analysed when it does not come from the drinking water network will allow you to assess its quality.
- Reminder of a horse’s water requirements
- Recommendations for the quality of drinking water for animals
- Possible consequences of poor water quality on a horse’s health
- Warning signs
- Why it is important to have water analysed
- To remenber
Reminder of a horse’s water requirements
Water is an essentiel nutrient and represents about 60 % of a horse’s body weight, which is around 300 litres for a horse weighing 500kg. On average, a 500kg horse will drink between 15 to 60 litres of water a day. This quantity of water consumed depends on several factors such as the amount of water in the food ingested, weather conditions, physical activity and physiological state.
Recommendations for the quality of drinking water for animals
The local sanitary regulations (Règlement Sanitaire Départemental (RSD)) stipulate that animals should have access to good quality drinking water. However there are no standards for « animal potability ». Animal drinking water should therefore comply to recommendations rather than standards with regard to physicochemical and bacteriological aspects. The recommendations of Sanitary Defense Groups (GDS) are mainly based on standards for drinking water for humans, with some tolerances.
| PARAMETERS | WARNING LEVELS from studies on the equine species (*), otherwise all species | REFERENCE VALUES (R) or LIMIT VALUES (L) for the quality of Water Destined for Human Consumption (WDHC) | |
| PHYSICOCHEMICAL | pH | 6 ≤ pH ≤ 9 | 6,5 ≤ pH ≤ 9,0 (R) |
| Conductivity | 200 ≤ conductivity ≤ 1100 μS/cm à 25°C | 200 ≤ conductivity ≤ 1100 μS/cm à 25°C (R) | |
| Total Dissoved Solids (TDS) | 4000 mg/L * | < 500 mg/L | |
| Total Organic Carbone (TOC) | 5 mg/L | 2 mg/L (R) | |
| Copper | 0,3 to 6,0 mg/L * | 1 mg/L (R) - 2 mg/L (L) | |
| Iron (Fe) | 0,3 mg/L * | 0,2 mg/L (R) | |
| Manganese (Mn) | < 50 µg/L | - | |
| Nitrate (NO3-) | 50 mg/L of NO3- | 50 mg/L of NO3-(L) | |
| Nitrite (NO2-) | 0,3 mg/L of NO2- | 0,5 mg/L of NO2-(L) | |
| MICROBIOLOGICAL | Total coliformes |
| Absence |
| Escherichia coli |
| Absence (R and L) | |
| Intestinal enterococcus |
| Absence (R and L) | |
Among the elements present in water, some minerals alter the taste (sodium, potassium, calcium, magnesium, iron, chloride and sulphate). These minerals are either present naturally or due to water treatment products added. Even though they are generally non toxic, horses are very sensitive to taste and /or smell, and may restrict their water consumption
A lot of substances are potentially toxic. Among these contaminants, pesticides (weedkillers, insecticides…), heavy metals, nitrites and nitrates, industrial pollutants or even bacteria and viruses.
The Sanitary Defense Groups (GDS) recommend an absence of any fecal germ in animal drinking water, as their presence indicates a poor sanitary state of the water, and a much higher risk of there being bacteria or infectious viruses, potentially dangerous for the horse’s health. They immediately lead to a decrease in animal water consumption.
Possible consequences of poor water quality on a horse’s health
Chart 2 below, indicates the possible unwanted side-effects following the ingestion of poor quality water, i.e. where the values are above those recommended in chart 1, for the parameters concerned (non exhaustive list)
| PARAMETERS | UNDESIRABLE EFFECTS |
| pH, Hardness, alkalinity | Decrease in consumption of food and water, weight loss, diarrhoea |
| Chloride, sodium, potassium, calcium, magnesium | Alteration of the taste of the water, leading to a decrease in consumption |
| Iron | Risk factor for the intestinal proliferation of the bacteria Clostridium botulinum (Risk of botulism), alters the taste of the water |
| Nitrates et nitrites | Acute gatritis (inflammation of the stomach mucous lining) |
| Bacteriology | E.g. : water contaminated by the urine of rodents, carriers of leptospirosis => diarrhoea, abortion in mares and death of foals |
| Cyanobacteria (toxins produced) | Photosensitivity, weakening, bloody diarrhoea, convulsions, death |
Warning signs
- Horses hesitant to drink => problem with the quality of water
- Drinking troughs dirtied by excretions => bad positionning of the troughs
- Long waiting time at the water troughs => insufficient flow
- Troughs which become green (algae proliferation), organic matter in the bottom (leaves) => lack of upkeep
Why it is important to have water analysed
To limit health problems linked to drinking water, it is advisable to have the water analysed if it is not from the drinking water network.
The quality of water can deteriorate between the source and when it ends up in the drinking trough. It is therefore important to analyse both the point of entry on the farm, and the animal’s drinking point
- In Spring, or during a period of flooding
• In Summer, heat can deteriorate the quality of water.
• In Autumn, when it rains
• And lastly during Winter
How to collect a sample of water?
By whom?
Samples can be collected by the farmer/ custodian, but it is possible to have a specialized technician come in to help the farmer in the interpretation of the results, and help in finding solutions where necessary. For example, the Sanitary defense Groups offer to carry out assessments of the quality of water for their subscribers, at competitive prices (more information from theGDS).
Where to collect the samples?
Ideally, the sample should be taken from the closest possible point to the animals’ drinking point, and from the source (water tower, well, borehole...).
What equipment should be used?
For the containers, you need at least :
- A sterile bottle to for the bacteriological analysis (of at least 1 liter in volume).
- A non-sterile bottle for the physicochemical analysis (of at least 1 liter in volume).
Most laboratories provide sampling kits with the bottles required for the analyses requested.
How should you send the samples?
The samples should be sent to the laboratory as soon as possible and ideally at a temperature of between 2°C and 8°C. The samples should be analysed within 24 hours after sample collection.
How much does it cost?
The price for a water analysis will vary depending on the laboratory and the type of analysis carried out. Generally for a full analysis, i.e. including bacteriological analysis (E.coli, enterococcus, total coliforms, revivable total colony count at 22 and 36°C and sulfate reducing anaerobic bacteria) and physicochemical analysis (pH, hardness, nitrates, nitrites, turbidity, total iron, conductivity) it will cost around €100.
To remenber
• To limit health issues linked to drinking water, it is advisable to have the drinking water analysed when it is not water from the drinking water network, and ideally at least once a year.
Know more about our authors
- Translated from french by : Karen DUFFY Translator
- Pauline DOLIGEZ Development engineer IFCE
- Marie DELERUE Veterinarian - development engineer IFCE
- Laurie BRIOT Research engineer IFCE
- Agata RZEKĘĆ Development engineer IFCE
Bibliography
- [1] OLKOWSKI A.A. (2009). La qualité de l'eau d'abreuvement du bétail - Guide de terrain relatif aux bovins, aux chevaux, à la volaille et aux porcs. Université de la Saskatchewan, Canada, 199 pages.
- [2] ANSES (2010). État des lieux des pratiques et recommandations relatives à la qualité sanitaire de l’eau d’abreuvement des animaux d’élevage. Saisine 2008-SA-0162, 124 pages.
- [3] MARTIN-ROSSET W. (2012). Alimentation des chevaux - Tables des apports alimentaires Inra 2011. Éditions Quae, 264 pages.
- [4] Directive (UE) 2020/2184 du Parlement européen et du Conseil du 16 décembre 2020 relative à la qualité des eaux destinées à la consommation humaine (refonte), Journal Officiel due l’Union Européenne, L 435, 23 décembre 2020, 62 pages
- [5] JONES W.E. (2004). Water dehydration and drinking. Journal of Equine Veterinary Science, 24, pages 43-44.
- [6] CLARKE L.L., ARGENZIO R.A. and ROBERTS M.C. (1990). Effect of meal feeding on plasma volume and urinary electrolyte clearance in ponies. American Journal of Veterinary Research, 51(4), pages 571-576.
