In dry summers, there may not be enough water to irrigate agricultural and horticultural crops. Since 2023, use of purified urban wastewater for this purpose has been allowed in the Netherlands. This water may still contain some chemicals and pathogens. It is therefore important that this water is sufficiently clean and safe. That is why RIVM has developed an assessment framework to test whether the use of purified urban wastewater is safe for people and for the groundwater ecosystem.
In 2024, RIVM conducted a study on the maximum amount of chemicals and pathogens that purified wastewater may contain so that crops sprayed with the water will still be safe for consumption.
In this follow-up study, RIVM examined human exposure through the air and through drinking water, and the exposure of the groundwater ecosystem.
Air and drinking water
There is a small risk of people becoming ill when they come into contact with this purified wastewater. This concerns people who work with irrigation water, local residents and passers-by.
No purified wastewater may be used in protected areas where drinking water is produced from groundwater. This is because of the risk that pathogens may end up in the drinking water through the groundwater. This is not the case outside these protected areas, where the wastewater can be used safely.
Background and recommendation
Since 2020, European legislation has promoted the use of purified wastewater for irrigation during droughts. The Netherlands implemented this legislation in 2023.
RIVM recommends that the Ministry of Infrastructure and Water Management (IenW), based on the results of this study, develop a tool for establishing in practice whether the use of purified wastewater is permitted in specific situations.