Pharmaceutical residues in drinking water 

A survey by the German Association of Energy and Water Industries (BDEW) revealed that 40% of the 1,000 households surveyed were concerned about drug residues in their water ¹. But are pharmaceutical residues in drinking water really a danger? And is there a need for action? Let's take a closer look!

In this Guidebook you will learn...

• ... whether medicines in Tapwater pose a health risk,
• ... how pharmaceutical residues get into bodies of water and drinking water in the first place, 
• ... how drugs in water affect humans, animals and the environment
• ... and how to take action against drug residues in drinking water. 

Drug residues in water: a health risk? 

Chemical trace analysis is now so advanced that drugs can now be detected in Tapwater even in the lowest concentrations. This was not possible for a long time! It is therefore not surprising that with this progress and the new findings, the public debate and thus also the fear of pharmaceutical residues in drinking water is increasing. 

In fact, drug residues are repeatedly detected in water - especially in rivers, lakes and soil and, less frequently, in groundwater and drinking water. However, the concentration of pharmaceutical residues in drinking water is currently still very low and amounts to just a few nanograms. 

According to the Federal Environment Agency (UBA), there is currently no risk for any age group when drinking water. According to current knowledge, concentrations of less than 0.1 µg/l (100 ng/l) per substance in drinking water are harmless. This means that medicines are present in Tapwater in far lower concentrations than would be necessary for therapeutic purposes. ²

Problematic active ingredients

In total, there are currently 3000 different active ingredients in more than 9000 preparations (both human and veterinary) in Germany. As of 2021, 414 different active substances have been detected in water to date, including ³:

By far the most frequently discussed active ingredient in this context is diclofenac. Diclofenac is only available on prescription in high doses, but is freely available in smaller doses (e.g. as an ingredient in ointments). The active ingredient has already been detected in sewage sludge, surface water, groundwater and drinking water ⁴. The death of vultures in India and Pakistan in the 1990s and kidney damage in rainbow trout have already been attributed to this drug and its entry into the water cycle.

In principle, ibuprofen is a good alternative as a painkiller, as it is much more biodegradable and therefore less ecotoxicologically harmful. However, the consumption of ibuprofen has risen so sharply in recent years that there is now a high level of contamination and residues of ibuprofen have been detected in drinking water - albeit in concentrations that were previously harmless.

Forecast for the future

So far, the concentration of pharmaceuticals in Tapwater has not yet been classified as dangerous. However, a worrying trend is emerging that must be counteracted at all costs. The biggest challenge is posed by an increasingly ageing society. The older we get, the more medication we consume, as the following statistics clearly show. ⁵

Per capita drug consumption of SHI-insured persons in Germany by age group in 2018

Source: https://de.statista.com/

In this context, a 2017 study by civity Management Consultants on behalf of the BDEW (German Association of Energy and Water Industries) assumes that the consumption of human medicines will increase by around 70 % by 2045. By then at the latest, drug residues could pose a real threat to our drinking water if no action is taken in time. ⁶

How do drugs get into Tapwater? 

In principle, medicines enter the water cycle both selectively or directly and diffusely. A distinction must be made between the different entry routes of pharmaceuticals from human medicine and those from veterinary medicine. 

Drug substances from human medicine

The most frequently prescribed human medicines include anti-inflammatory drugs, asthma medications and psychotherapeutics. Residues of these drugs primarily enter the water cycle directly via wastewater. This happens both when they are excreted from the human body and when ointments and creams are washed off. As many active substances are not completely broken down in the body, some of them enter the water cycle unchanged and together with their degradation products. ⁷

However, improper disposal can also lead to pharmaceutical residues being released into the water. Discharges from the manufacture of pharmaceuticals or the treatment and disposal of hospital wastewater and waste are also a cause for concern.

Although our wastewater is continuously purified in sewage treatment plants, these are not usually designed to filter pharmaceuticals out of the water without leaving any residue. Ibuprofen, for example, can be removed with an efficiency of 60-80%. The X-ray contrast agent Iomeprol, on the other hand, can only be removed with an efficiency of 40-50%.

Even if these substances are retained, a new problem arises: sewage sludge is often used as a fertilizer in agriculture. If the sewage sludge is spread on the fields, the pharmaceutical residues it contains end up in the groundwater via the soil and ultimately in the drinking water.

Drugs from veterinary medicine

Important pharmaceuticals from veterinary medicine are primarily antibiotics, antiparasitics, anti-inflammatory drugs and hormonally active substances. These primarily enter groundwater and surface water via liquid manure, pasture farming or aquaculture through seepage and rain.

In addition, carry-over when administering medicines in stables as well as improper storage and disposal can lead to veterinary medicines entering the water cycle. Equally problematic are fermentation products from biogas plants that are spread on fields as fertilizer. Fish farming should also not be forgotten. Here, pharmaceuticals are introduced directly into the water via the feed and carried on from there.

Drug substances in the environment: effects

Whether pharmaceutical residues in water have negative effects always depends on the respective active ingredients. Substances that are persistent, mobile and toxic are particularly problematic.

• persistent = the substance is poorly degradable (degradability)
• mobile = the substance can be displaced in the water (displacement behavior)
• toxic = the substance has a toxic effect on humans, animals and/or the environment (toxicity)

Since 2006, pharmaceuticals have had to undergo an environmental risk assessment prior to approval. Here, problematic active substances and their risk to water and soil are determined. The aforementioned factors of degradability, translocation behavior and toxicity are the guiding principles. However, there is little or no data available, at least for those medicines that were approved before 2006 (existing active substances). ⁸

For this reason, the dangers of pharmaceuticals in the environment and in water are still partly unknown. Just as little data is available on so-called mixed effects - i.e. the interaction of residues of different pharmaceutical substances. Here are some examples of possible harmful effects that have already been proven ⁹:

What can be done about pharmaceutical residues in drinking water?

In order to reduce drug residues in drinking water now and in the future in the best possible way, a holistic approach is needed that starts at different points. Politics, water management, agriculture, healthcare and consumers must all play their part in order to protect people and the environment in the long term.

Politicians, the water industry and the healthcare sector can do this: 

• Separate treatment of hospital wastewater
• Additional purification stage in wastewater treatment plants
• Limit values for the concentration of drug residues in water
• Consideration of environmental aspects in the development of medicines
• Alternative forms of therapy
• adapted prescription practice
• Promoting a healthier lifestyle

Agriculture can do this: 

• Efficient application of fertilizer close to the ground
• Less application of fertilizers of animal origin 
• Seasonal and weather-adapted fertilization
• Responsible handling of veterinary medicinal products

This is what consumers can do: 

• Use of drinking water filters in private households
• No stock purchases of medicines
• Responsible level of self-medication
• Correct disposal of unused medication

Drug residues in drinking water: a problem of the future? 

Although the concentration of pharmaceutical residues in drinking water is not yet a cause for concern for humans, the first negative effects in the environment are already becoming apparent. The fact is: water as a habitat and as the basis of human life must be protected! Only if all authorities make their necessary contribution can the quality of our waters and our drinking water be safeguarded for the future.

FAQs on medication in Tapwater

Are there drug residues in the Tapwater ?

Yes, there are drug residues in our Tapwater . However, the concentration is still so low that no negative effects on human health are feared. 

Are there estrogens in Tapwater?

Yes, oestrogens and other hormones repeatedly find their way into drinking water. This is mainly due to incorrect disposal of medicines, industrial waste and natural excretion (contraceptive pill). 

Can drug residues be filtered out of the Tapwater ? 

In some places, a 4th purification stage is implemented in wastewater treatment plants to filter medicines out of the water. Primarily ozonation and activated carbon filters are used here. Such processes can remove up to 90 % of the substances. Private individuals can also reduce pharmaceutical residues in water with the help of a suitable drinking water filter. 

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