Residue monitoring in drinking and groundwater

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Changed on: 15.07.2020

Drinking water is obtained almost exclusively from groundwater in Austria. Drug residues (as well as pesticide residues) have been detected in Austrian groundwater since the beginning of the 1990s. This also applies to so-called waste water indicators, such as sugar substitutes or industrial chemicals, which are usually found in urban wastewater.

As a result, the Federal Ministry of Health (BMG) commissioned the research project “Monitoring Programme for Pharmaceuticals and Wastewater Indicators in Drinking and Groundwater” in 2014: the programme used random samples to find out what types of antibiotics, pharmaceuticals and wastewater indicators can be detected in ground and drinking water. The project was carried out by AGES and the Environmental Agency Austria.

Sample-Taking in Austria

A total of 54 groundwater measuring points were chosen across Austria: earlier surveys had suggested that residues could be expected at these locations. In other words, the selection represented a worst case scenario. Secondly, 50 drinking water measuring points were picked around these groundwater measuring points.

The water samples were tested for a total of 37 antibiotic agents and eight lead substances (sugar substitutes, industrial chemicals, pharmaceuticals). Antibiotic agents were found during at least one analysis round at seven groundwater test points (13%) and five drinking water test points (10%). The majority of the levels detected were a few nanograms per litre. One nanogram (ng) is a billionth of a gram. The highest levels were 21 ng/l in groundwater (sulfamethoxazole, an antibiotic) and 5.6 ng/l in drinking water (sulfamethoxazole). These levels of concentration are below the levels for human toxicity toleration. A minimum of one wastewater indicator (mostly the sugar substitute acesulfame potassium) was detected at 46 groundwater testing points (85%) and 31 drinking water testing points (62 %) during at least one analysis round.

While other antibiotic residues (incl. erythromycin, lincomycin, sulfadimidine and sulfathiazole) were detected in groundwater in addition to sulfamethoxazole, sulfamethoxazole was the only one found in drinking water. This substance is used in both human and veterinary medicine. However, residues for the wastewater indicator carbamazepine (epilepsy medication) could be detected quite often at these measuring points, suggesting that the contamination of drinking water with antibiotics can be attributed mostly to their use in human medicine and not agricultural use.


Austrian ground and drinking waters contain levels of antibiotics to a degree that poses no toxicologic threat to human health. This is also true for the wastewater indicator residues detected. However, even such minute levels of antibiotics (nanograms) can contribute to bacteria developing resistances. The presence of pharmaceuticals and industrial chemicals in drinking water still represents a risk with regards to undesired synergy effects, even at the minutest levels. Thus, the reasons for the presence of such substances must be clarified, the sources identified and measures taken to minimise or even eliminate their presence in drinking water.

The import vectors in regards to pharmaceutical substances into ground and drinking water vary: human medicines are excreted partly unchanged or in the form of metabolites (degrading products) after ingestion. If they cannot be removed completely during wastewater treatment, they may find their way into running water and groundwater. They can also get into the groundwater via leaking sewers and from there in our drinking water. Veterinary pharmaceuticals can get into water via seepage and surface runoff. Substances such as sugar substitutes or industrial chemicals are very difficult to degrade using microbiological processes given their chemo-physical behaviour, thus contaminating watercourses and groundwater via sewers.

Final report Monitoring Programme for Pharmaceuticals and Wastewater Indicators in Ground and Drinking water.