EU guideline for manufacturers of plant protection products and biocidal products to protect drinking water production

KWR co-authors guidance document for European Commission

A guideline was published recently with the aim of mapping out the impact of plant protection products, biocidal products and their transformation products on the production of drinking water. For the drinking water sector, this guidance document means that, before they can market new products, manufacturers will be required to demonstrate that the products do not pose a danger to drinking water production.

“It is very welcome that the EU is taking the initiative to protect the quality of drinking water – and therefore our health – with guidance like this,” thinks KWR researcher Roberta Hofman. She co-authored the document, which is more than 100 pages long: ‘Guidance document on the impact of water treatment processes on residues of active substances or their metabolites in water abstracted for the production of drinking water’. KWR drafted the guideline in collaboration with IWW Water Centre, KWR’s German counterpart, for the European Commission.

Drinking water treatment

New plant protection products and biocidal products are required to be tested for potential harm to humans and the environment before they go on the market. But when they are used on the land after approval, these agents can leach into surface water or seep into groundwater. There is then a possibility that they may enter sources of drinking water. If they do so, the transformation products of some substances may be formed during subsequent water treatment. How can drinking water producers be sure that substances of this kind will not affect the health of their customers?


This question was submitted to KWR by the European Food Safety Authority (EFSA) and the European Chemicals Agency (ECHA). “The guidance document is certainly not looking to make changes in drinking water production,” emphasises Hofman. “No changes will be made to the methods in place. I would therefore prefer to describe the document as a ‘cookbook’ for manufacturers, setting out what they need to do to demonstrate that a new plant protection product or biocidal product doesn’t constitute a risk for drinking water production. They can then submit the results of these analyses to the authorities responsible for authorisation in the different EU Member States. The document describes the approach required, and why which analyses are suitable, for all the usual disinfection methods. The title of the document also includes the word ‘metabolites’. These are substances formed as a result of microbiological and chemical processes after the agents enter the environment. It is very important to include these substances in the picture as well.” Using the ‘cookbook’, manufacturers can determine whether new substances could be formed from their products or the associated metabolites during drinking water treatment. The document then also sets out the approach, on the basis of expected concentrations and toxicological information, for determining whether those substances are potentially harmful to health. This allows for the implementation to a certain degree of extended producer responsibility.

Long road

Hofman says that the drafting of the document was a long road. “After the draft had been completed, the outside world was given the opportunity to comment. I understand that manufacturers are critical. The guidance means extra work, and therefore extra costs, for them. And at the EU, too, a lot of people had to be got on board. But now that the guidance is in place, I hope we can assume that, when a new plant protection product comes into the market, it will not cause a problem with drinking water treatment.”