Boil notices

Impractical boil notices

Five major boil notices were issued by Dutch drinking water utilities in 2024. Two notices were issued in 2025 and one in January 2026. That is well above the average of one in previous years, according to a survey by the Inspectorate for the Living Environment and Transport. The boil notice states that consumers should boil tap water for 3 minutes. However, the three-minute recommendation suffers from a number of drawbacks in terms of practicality. That could limit compliance with a boil notice and therefore reduce the measure’s effectiveness. Karagiannis et al. (2009) concluded that 2% of respondents did not comply with the boil notice because it was too much work. Boiling for 3 minutes also introduces new risks such as burns from hot pans, and it may result in malfunctions in appliances such as kettles. The 3-minute boiling time also uses extra energy, which customers may see as a drawback. Bottled water is considered to be an unsustainable alternative. The WHO, and also a recommendation issued by KWR in the past, has stated that heating water to a rolling boil provides consumers with an adequate level of protection. Given the WHO recommendation, the boiling time in Flanders has been reduced from 5 minutes to 1 minute, with the decision to opt for 1 minute being made for communication reasons.

The question has been raised in the drinking water sector as to whether the boil notice in the Netherlands can be brought into line with the WHO’s position. In order to convince the relevant authorities, further information is required in relation to the previous decision in 2011 to maintain a time of 3 minutes. The aim of the project is to provide new evidence that the ‘rolling boil’ approach provides consumers with an adequate level of protection, possibly in combination with insights that the approach results in a significantly higher rate of compliance with boil notices, fewer accidents or damage in the home, and lower energy consumption or fewer purchases of bottled water. It is known that current research into the difference between the rolling boil approach and boiling for 3 minutes has extrapolated the results for 60 degrees Celsius to 100 degrees Celsius. This introduces an element of uncertainty into the basis for the current boil notice that can be resolved by conducting a study into the elimination of bacteria at temperatures up to 100 degrees Celsius.

Furthermore, the 3-minute recommendation is based on, among other things, research in which micro-organisms were exposed to boiling water for 1 or 3 minutes but which did not take into account the time taken to reach boiling point. Taking this lead time into consideration in a new study will allow for a more realistic picture of the effectiveness of the rolling boil approach.

In addition to the boil notice, the document ‘Questions and Answers relating to a Boil Notice for Professionals in the Drinking Water Sector’ was drawn up by the RIVM in 2009 and discussed by the Water Quality Advisory Group and the NBC Drinking Water Expert Platform, in consultation with Vewin’s communications department. It explains, for example, which appliances are suitable for a three-minute approach (such as a hot-water tap) and which are not (such as a kettle or coffee machine). This project may result in recommendations for the amendment of these recommendations. However, this study will not make an assessment of all possible options.

Desinfection by boiling and determining user behaviour

The latest scientific insights will be updated by studying the literature about the inactivation of micro-organisms by heating or boiling water. In addition, a critical evaluation will be conducted of the current recommendations issued by RIVM and the paper on which the current boil notice is based (Bertrand et al. 2012).

This will constitute the basis for experiments targeting, for example, the organisms to be studied, the experiment design and other aspects of the research. Laboratory experiments will be conducted to investigate the effectiveness of a full rolling boil approach in terms of eliminating the micro-organisms that are relevant for drinking water.

In collaboration with the drinking water utilities, information will be gathered about practical matters relating to the boil notice. When boil notices are issued, drinking water utilities may conduct surveys of their customers relating to matters such as:

• compliance with boil notices and the impact of their practicality on compliance;
• implementation risks associated with boiling for 3 minutes as opposed to bringing water to the boil;
• other experiences with the implementation of boil notices, such as damage to equipment (experiences of drinking water utilities);
• customer experiences with boil notices that are relevant for recommendations; and
• clear communications with customers.

Proposal for amendment of boil notice

The aim of this project is to collect new insights that support the view that the current recommendation to boil water for 3 minutes could be amended to advise a shorter boiling time or heating water to a rolling boil. In addition, information about compliance and problems associated with a boil notice are being collected from the literature and water utilities in order to establish a clearer picture of the impact of a 3-minute boil notice on compliance and the potential risks involved in implementing the notice.

If the results justify doing so, they will be submitted to the ILT with a proposal to amend the notice. This could help to reduce health risks during periods in which boil notices are in place as a result of improved compliance and result in fewer risks during the implementation of the boil notice. In theory, this will also result in energy savings and a reduction in purchases of bottled water.