Drinking water quality

Explanation of the problem

If the temperature of the drinking water rises too much, there is a greater risk of a decline in water quality. There is a correlation between temperature and the number of complaints about brown water. Additionally, in warm drinking water, microorganisms such as Legionella can grow more rapidly. This is primarily a concern for water supply companies but can subsequently have negative effects on public health, agriculture, livestock farming, and industry. Tap water should not be warmer than 25°C, which is a legal requirement under the Dutch Drinking Water Act that water supply companies must comply with. The drinking water temperature rises when pipes are close to the surface and when the ground surface becomes hot, causing the soil to warm up. Warming of the drinking water network is also related to other factors such as soil coverage and albedo, soil type, sun/shade, depth of pipes, and the presence of anthropogenic sources (above ground, such as residual building heat, building density, electric charging stations; and below ground, such as district heating networks, geothermal systems, and high-voltage cables that can reach temperatures of up to 90°C). Additionally, tap water in apartments and offices can warm up further as it travels a long way through the building, and these water pipes are not always adequately insulated from other (hot) pipes.

Information and maps for better understanding

Basic maps according to the standardized stress test

  • Detailed heat map of the perceived temperature on a hot day Climate Impact Atlas) → to determine where drinking water pipes are at risk of overheating.

Additional maps

  • Map showing the number of summer or tropical days now and in the future (Climate Impact Atlas) → provides an indication of the increase in the number of days when work productivity may decrease.
  • Various maps of soil properties and spatial characteristics that influence the temperature in drinking water pipes:
      • Location of the pipes (including known depth).
      • Coverage.
      • Albedo.
      • Soil type.
      • In sun/shade.
      • Location of potential heat sources (anthropogenic sources above and below ground).

Some measures and guidelines

  • Install drinking water pipes deeper.
  • Install drinking water pipes in shaded areas as much as possible.
  • Install drinking water pipes under greenery.
  • Avoid placing drinking water pipes near heat sources.
  • Avoid running water pipes along the south facade of apartment buildings or better insulate them.