How climate change affects drinking water supply

Berlin It is an ambitious goal: by 2045, the building stock in Germany should be climate-neutral. That’s what the federal government decided. The Handelsblatt Research Institute (HRI), together with the sanitary company Viega, has now examined what consequences the climate targets can have on drinking water quality. The bottom line: there is a conflict of objectives between energy efficiency and high-quality drinking water.

In order to achieve drinking water quality, the operating temperature in buildings must be constantly at least 55 degrees. Otherwise there is an increased risk of bacterial contamination, especially with legionella. In the worst case, these can trigger a special form of pneumonia. Possible causes are insufficiently insulated drinking water pipes, little-used pipe sections or hot water storage tanks that are operated below 60 degrees Celsius.

But heating consumes energy: With an average hot water consumption of 40 liters per day, the energy required for heating is between 1.65 and 2.2 kilowatt hours (kWh) per day and person. According to calculations from 2018, the share of hot water in the final energy consumption of a private household accounted for around 16 percent, according to the study.

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One appeal of the study is therefore that the climate targets should not lead to restrictions on heating, but that climate-friendly technologies should be used instead. “Technical solutions are needed that ensure drinking water hygiene with lower energy consumption,” explains Sven Jung, who played a key role in the study at the HRI. Even with climate-neutral construction, care must be taken to ensure that the water temperature is sufficient.

As examples of innovative technologies that could combine climate protection and drinking water quality, the HRI cites “decentralized heat exchangers, energy recovery from wastewater, better insulation of hot water systems and more economical heat generators with good energy utilization, such as condensing boilers”.

Hygiene concept for drinking water

“In order to ensure high drinking water quality in the future and thus protect our health, the appropriate course must be set now,” says Bert Rürup, President of the HRI and scientific director of the study. Politics is also required.

In order to reconcile climate protection and health protection, the study therefore recommends, among other things, a mandatory drinking water hygiene concept comparable to fire protection for builders. In addition, innovative digital technologies are to be used in drinking water systems and in the construction and operation of buildings, and standards are to be monitored regularly.

Politicians are also responsible for maintaining the public water infrastructure – a significant cost item that has grown over the years and amounted to around 3.2 billion euros in 2020. For comparison: in 2010 the investment volume was just under 2.2 billion euros. In its study for the public sector, the HRI also warns that residues from medicines, cosmetic products, cleaning agents and pesticides – so-called anthropogenic trace substances – are increasingly affecting water quality.

Manure fertilization near Goslar

Limit values ​​for nitrate pollution are often exceeded.

(Photo: imago images/Martin Wagner)

A high nitrate concentration, which often exceeds the limit values ​​set by the EU, can also affect the quality of drinking water. Nitrate gets into the groundwater mainly through the fertilization of agricultural land. In addition to exposure to chemical substances, the HRI also assumes that climate change will change both the supply and demand for drinking water in the future. The changing meteorological conditions could lead locally to falling, rising or fluctuating groundwater levels.

Regional drinking water rationing

Because in the future, a “shift in the amount of precipitation” is to be expected: the summers would be drier overall and the winters wetter and milder. Extreme weather events such as floods and droughts could also pose challenges for the water supply in Germany in the future. According to the HRI, a general lack of water does not pose a fundamental challenge in this country, unlike in other parts of the world.

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Nevertheless, regional drinking water rationing also occurs more frequently in Germany due to water shortages. In April, for example, the Strausberg-Erkner water association announced that it would agree on a cap on the water supply with new customers. The water association is also responsible for the Tesla plant in Grünheide, Brandenburg. Increasing demand for water had caused the association to exceed the approved groundwater abstraction levels.

“For a long time, the supply of drinking water in Germany was not an issue that received particular attention,” says HRI boss Bert Rürup. Clean drinking water was practically always and everywhere available in this country. However, that has changed a bit in recent years.

More: Water is becoming scarce in the world – this is fueling more and more conflicts

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