Plant protection products & pesticides in groundwater and drinking water 

Pesticides are among the most discussed pollutants in our waters. The pesticides and herbicides are applied to protect our crops, but end up in our waters and ultimately in our groundwater and drinking water via various routes. Want to find out more about pesticides in drinking water? Then you've come to the right place!

In this Guidebook , we explain to you...

• ... exactly what plant protection products or pesticides are, 
• ... whether and in what quantity they occur in groundwater and drinking water, 
• ... what the legal limits are for pesticides in drinking water, 
• ... how pesticides get into drinking water, 
• ... what effects plant protection products have on people and the environment
• ... and how pesticide residues in water can be reduced.

Plant protection products vs. pesticides: what's the difference?

Plant protection products are chemical or biological products that are used to protect plants from harmful organisms. They contain one or more active ingredients, known as pesticides. 

Pesticides are therefore the individual active ingredients used in plant protection products to repel or combat certain harmful substances. The best-known pesticides are 

• Herbicides against weeds
• Insecticides against insects
• Fungicides against fungi and spores
• Acaricides against spiders and mites
• Bactericides against bacteria
• Rodenticides against rodents
• Molluscicides against snails

Plant protection products in groundwater and drinking water: current test results

Pesticides or their degradation products (metabolites) are repeatedly detected in surface and groundwater, and somewhat less frequently in drinking water. In 2019, for example, the threshold value or environmental standard was exceeded for at least one pesticide in a quarter of all reported monitoring sites in European waters ¹.

The report by the Federal Ministry of Health and the Federal Environment Agency on drinking water quality in Germany also revealed that the limit value of 0.1 µg/l was exceeded for 4 of the 349 active substances or metabolites examined in the reporting period from January 2017 to December 2019 ². The substances in question are 

• trans-heptachlor epoxide
• Desethylatrazine
• Glyphosate
• Dikegulac

Further test results can be found in the raw water database for water supply set up by the DVGW-Technologiezentrum Wasser. In the period from January 2010 to March 2020, the limit value of 0.1 µg/l set for drinking water was exceeded at 228 of the 5659 raw water withdrawal points tested in Germany. 

The exceedance for the individual active substances (e.g. bentazone, metamitron and glyphosate) was at most in the lower per mille range and for the metabolites in the lower single-digit percentage range. ³

Pesticides in drinking water: legal limits

According to the German Drinking Water Ordinance, the limit value for most pesticides is 0.1 µg/l per individual active substance or their relevant metabolites. In total, the concentration must not exceed 0.5 µg/l ⁴. The same values are also specified in the Groundwater Ordinance ⁵. 

The problem is that a distinction is made between "relevant metabolites" and "non-relevant metabolites" in the case of metabolites, i.e. the degradation products of pesticides. 

• Relevant metabolites have a similar pesticidal effect to the parent substance (active ingredient) and may have a toxic effect on humans and the environment. The same limit values apply to them as to the active substances themselves.
• Nicht relevante Metaboliten wirken nicht gleich wie das ursprüngliche Pestizid und weisen eine geringere Toxizität (< 50% des Wirkstoffes) auf. Für diese Abbauprodukte gibt es keine einheitlichen oder verbindlichen Grenzwerte in der Trinkwasserverordnung, sondern nur einen Richtwert von 10 µg/l gemäß der Pflanzenschutzmittelzulassung sowie 1-3 µg/l laut gesundheitlichem Orientierungswert (GOW) des Umweltbundesamtes ⁶. 

The Federal Environment Agency strongly criticizes the fact that the non-relevant metabolites are played down and calls for an appropriate approach to this group of substances. This is because they do pose a risk - even if it is smaller compared to the pesticides themselves and the relevant metabolites. Furthermore, not all substances known from the approval procedures are measured. Of a total of 300 known non-relevant metabolites, only 50 are regularly monitored. 

The fact is that these non-relevant metabolites were detected in 58% of the groundwater monitoring wells investigated throughout Germany - and in some cases in concentrations above the GOW. ⁷

How do pesticides get into drinking water? 

Grossly negligent behavior and accidents can lead to large quantities of pesticides entering the groundwater and ultimately the drinking water. However, even if pesticides are used responsibly and appropriately, they are constantly being released into groundwater and drinking water. 

The majority of pesticides are released directly into the environment when they are sprayed on fields. Some of these penetrate the soil, where new substances (metabolites) are formed. Some of these degradation products are very mobile and seep easily into the groundwater, from where they enter drinking water. The wash-off into adjacent bodies of water due to rain is just as problematic. 

Pesticides in drinking water: effects on humans and the environment 

Article 4 of the EU Plant Protection Products Regulation 1107/2009 stipulates that plant protection products must not have any demonstrable harmful effects on humans or the environment for their authorization ⁸. Nevertheless, it happens time and again that harmful effects are only discovered years after authorization. 

It is clear that excessive use of pesticides poses a huge threat to biodiversity in the animal and plant kingdoms ⁹. Here are a few examples: 

• Herbicides lead to the decline of endangered wild herbs and grasses.
• Pesticides harm insects, including important pollinators such as bees. Both insects that are sprayed directly and those that come into contact with sprayed plants are at risk. 
• Birds are harmed on the one hand by direct contact with the pesticides and on the other by the loss of breeding sites and food.

Pesticides can also be dangerous for humans. For example, pesticides have fallen into disrepute...

• ... promote the development of cancer.
• ... to disrupt cell division.
• ... impair the immune system.
• ... to influence the hormone system.

However, according to the report by the Federal Ministry of Health and the Federal Environment Agency mentioned above, the pesticide concentrations measured in drinking water do not pose a risk to our health. This is because the limit values are far below the level that would be of toxicological concern. Greater risks are posed directly by the application of pesticides and the consumption of contaminated food.

Reducing pesticides in drinking water

The primary goal must be to reduce the use of pesticides. This is also what the EU Commission is calling for with its proposal to halve the use of pesticides by 2030 ¹⁰. This applies to agriculture and forestry as well as private individuals. Some important measures to reduce the use of pesticides and their entry into the water cycle include 

• Relevant political incentives and subsidies to support farmers in sustainable farming.
• Binding regulations and limit values for non-relevant metabolites.
• Tilling the agricultural soil to reduce the infiltration of pesticides. 
• Construction of retention systems and vegetated buffer strips along watercourses.
• Robust plant selection and use of beneficial insects and mechanical or thermal methods against weeds in private gardens. 
• Purchase regional and seasonal food from sustainable sources.

As an immediate measure, we recommend that private individuals use a suitable drinking water filter. Although this does not solve the underlying problem, it will immediately provide you with clean drinking water. 

We at Alb Filter offer you the two activated carbon filters Active and Active Plus+ for this purpose. Thanks to their extended filter spectrum, they reliably remove pesticides from your drinking water. The adsorptive effect of activated carbon is particularly important here. It ensures that the pesticide residues are absorbed and bound by the carbon. 

"No" to pesticides in drinking water - "Yes" to clean water

Pesticides and plant protection products pose a threat to our environment, water bodies and therefore also to our drinking water. Action is needed to prevent further contamination with pesticides and herbicides. The strategy is: use pesticides as sparingly as possible or not at all and enjoy clean water! 

FAQs on pesticides in drinking water

What pollutants are there in drinking water? 

Our drinking water contains numerous different substances, some of which are harmful. Undesirable substances include pharmaceutical residues, hormones, microplastics, pesticides and heavy metals. 

Can pesticides be filtered out of drinking water? 

Yes, pesticide residues can be filtered out of drinking water with an activated carbon block filter. At Alb Filter you will find the two drinking water filters Active and Active Plus+. These have an extended filter spectrum and can filter pesticides from your drinking water. 

What do pesticides do in the body?

Pesticides can have a number of negative effects on the body. These include, for example: 

• Disruption of cell division
• Favoring the development of cancer
• Impairment of the immune system
• Intervention in the hormone system

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