Quality of drinking water

There are no legal criteria in Europe for determining the quality of drinking water for livestock. However, the drinking water quality still has to meet specific criteria since animal products intended for human consumption are subject to specific requirements as well. The safety of water is assessed based on bacteriological criteria (total bacterial count and the number of coliform bacteria) and chemical parameters.

The table below summarises the interpretation of water quality parameters according to GD Deventer in the Netherlands.

Source: GD Animal Health (Netherlands)

* The values in the 'good' columns represent no negative effects for the animal in question. The 'abnormal' columns represent the limits where the animal does experience negative effects.

Drinking water is unsuitable for livestock if:

One or more parameters exceed(s) abnormal values.
Three or more parameters are ‘good’ to ‘abnormal’.

Monitoring Water Quality

It is important to check the water quality on a regular basis to ensure that it meets the standards consistently.

This video demonstrates how to take water samples in order to test the water quality in a stable.

The table provides some guidance on sampling frequency and location.

	Well water		Tap water
	Frequency	Where
Chemical test	new well: at least 4x/yr stable well: at least 1x/yr	right after purification	not needed
Bacteriological test	at least 2x/yr	right after purification	not needed
		header tanks	header tanks
		where the animals drink	where the animals drink

More details about where to take water samples

The goal of water quality testing is to minimise the risks that the animals are exposed to. This means that samples should be taken at high-risk areas:

If header tanks are present on a farm, a sample must be taken from a tank located at the end of the drinking water system, preferably inside the animal compartment and/or in a warm location. Submerge the sample container and open the lid. Allow the container to fill and close the container before taking it out of the water. This will prevent any dust floating on the surface of the water from contaminating the sample.
Water samples from a drinking nipple/trough or cup. Always take samples as far down the drinking line as possible. Preferably from a section with a low water flow rate and a high temperature (for example young animals). If a sample cannot be taken directly from the drinking point, collect water from a flush tap at the end or disconnect the pipe at the end. Collect the first 1 to 3 litres in a clean (white) bucket and take your sample from the bucket.
If medication was recently administered to the animals via the drinking water, it is recommended to take a sample from this section as well. Once again, take the sample from the last drinking point. Record the number of days since the animals received medication in their drinking water, as well as the medication that was administered last, on a lab form.
On sow farms, the piglet nipple in gestation crates requires special attention because it is idle for roughly the first ten days after birth and temperatures are high. Four to seven days after a litter was born, take a sample from the piglet nipples. Again, it is best to choose a nipple as far as possible down the drinking water system. For comparison, a sample can be taken from the sow nipple in the same gestation crate.
In the sickbay, the risk of infection is high, the flow of water is usually low and medication may be used more frequently.
Many organisms grow in stagnant water, so an empty animal compartment can provide useful water samples.

Poor water quality can lead to a range of different problems. Click here to read more about common problems.

Hard water

Water hardness is defined as the sum of calcium (Ca) and magnesium (Mg) expressed in mmol/l or the sum of calcium and magnesium expressed in °D (German hardness degrees) 1°D is 10 ppm CaO (10 mg/L).

Hardness ≥ 20°D affects water flavour, but animals are known to adapt. At levels exceeding 25°D, the animals will start drinking less water.

Very soft water (<4°D) can lead to corrosion of pipes because of lower pH.

Hard water also causes deposits of Ca scaling.

For both pigs and poultry, safe drinking water pH levels are between 5 and 8.5. If the drinking water pH drops below 4 or exceeds 9, its flavour will be poor. The animals will drink less, which will cause them to eat less as well.

The pH of the water depends, among other things, on the water’s buffering capacity, which in turn is determined by the hardness of the water: the harder the water, the higher the buffering capacity. Very soft water with a hardness of 0°D will lack any buffering capacity. Small changes are then able to lead to significant increases in acidity which may cause corrosion to the pipes. A hardness of 4°D is required to prevent damage to the drinking water system.

Iron

Iron (Fe) is very common in drinking water, although concentrations vary by region. It may cause:

clogged drinking nipples and red / brown deposits if >2.5 mg/L.
formation of complexes with certain medicines (e.g., tetracyclines) in the water if >5 mg/L.
abnormal taste of the water causing reduced intake if >10 mg/L.
diarrhea if >30mg/L.

When using galvanised pipes the iron concentration in the pipes can be higher than in the stock solution. So even while the stock solution was clear, precipitation might occur in the pipes.

Manganese

Manganese (Mn) is also quite common, and once again regional differences apply. At levels of >2 mg/L manganese may:

corrode stainless steel pipes, which leads to
1. roughening of the inner surface and higher risk of biofilm formation.
2. leaks in the system in the end.
form black deposits due to a reaction with oxygen in the water.
cause the water to taste bad (reduced water intake).

Quality of drinking water

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