The influence of drinking water quality on the efficacy of antibiotics

The influence of drinking water quality on the efficacy of antibiotics

Medication is often administered via drinking water. This allows the drug to be easily administered, ensures it can be accurately dosed, and the way of administration or the dosage can be easily adapted. The quality and features of the drinking water and the drinking water distribution system can, however, have an effect on the efficacy of the medicinal products. 

Drinking water quality

The quality of drinking water can vary widely. Groundwater quality can differ depending on the depth and region from where it is extracted. Even tap water, which has to meet strict quality standards, can vary in quality from region to region. These differences in quality can affect the solubility and the way in which the medications work (antibiotics and vaccinations).


Water hardness is a measure of the concentration of metal ions – mostly magnesium and calcium carbonate, but also bicarbonates and sulphates – in the water. If the water hardness is high, there is a greater risk that these metals are present and so additional measures need to be taken before you can start any treatment with antibiotics in drinking water. This is because complexes (connections between antibiotics and metals) can be formed with the antibiotics and these cannot be absorbed in the body. This is particularly the case with doxycycline, oxytetracycline and flumequine.

With very hard water, a biofilm is formed in the pipes much earlier on, which can cause bacterial contamination levels to soar. Hardness can be easily measured using a drop test. We can advise you about this.

pH value

The pH is a measure of the acid value (also known as acidity) of an aqueous solution. The pH of good quality water at room temperature is around 7. Acid solutions have a pH that is lower than 7 and therefore a high acid value. Alkaline solutions have a pH higher than 7 and therefore low acidity. The pH value can differ per water source, which can affect the solubility of certain antibiotics. 

The pH value of water can be measured using a pH meter or simply with litmus paper. The litmus paper can be dipped into the drinking water to measure the pH value. The paper then changes colour and this is indicative of the pH value.

Drinking water quality and antibiotics

The influence of the pH value on the way antibiotics work depends on the type of antibiotics. Below, we will discuss the kind of antibiotics that most often experience problems in relation to water quality.

Tetracyclines (doxycycline, oxytetracycline) 
Tetracyclines generally dissolve poorly in water. Their solubility is optimal at a low pH value. 

In hard water, calcium binds with all tetracyclines, such as oxytetracycline. Acid can be added to hard water (Citric Acid), so that the calcium reacts with the acid and not with the tetracycline; the oxytetracycline is thus freely available. The Citric Acid datasheet contains a table that explains the dosage of Citric Acid. 

Sulfonamides can bind with organic substances. With treatment involving sulfonamides (for example, Trisul 80-400 wsp, Trisul Forte wsp, Prococ wdp, Vitacox Plus wsp, Vitacox wdp), it is therefore particularly important to ensure clean drinking water pipes. 

Ampicillin and amoxicillin 
Ampicillin and amoxicillin dissolve better in a neutral to alkaline environment. They are very sensitive to temperature fluctuations and to beta-lactamase producing bacteria in the drinking water system. These can inactivate amoxicillin and ampicillin. Amoxicillin mixed with water therefore only lasts 6 hours. The animals should be given the amoxicillin mixed with a limited amount of water, so that they can drink it all within a given time.

Most antibiotics are perishable in a pre-solution. The shelf life of medicated drinking water is always stated on the label and on the datasheet of a product that can be found in the catalogue on our website

Drinking water system

With a good drinking water system, you can administer medication on a per stall basis so animals do not come into contact with...

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