Climate change to threaten Swiss drinking water supplies

Concerns about the effects of climate change on the nation’s drinking water supplies emerged at this week’s conference, jointly hosted by the Swiss gas and water industry association (SVGW) and the Swiss federal institute of aquatic science and technology (Eawag). More than 150 scientists took part.

The country’s tap water is generally gleaned from two sources: lakes and groundwater wells. Dr. Wouter Pronk, an expert at the Eawag process engineering department, told Swisster after the conference: “If extreme weather events increase there will be more problems. For instance, algae blooms [in lakes] are very dependent on temperature and some species are toxic.”

“We have more and more problems especially with the melting permafrost,” said SVGW technical consultant, Markus Biner.

“Increasing amounts of particles are washed down from the mountains and we then need to filter this water. Even now in some places it has a brownish colour, which was not the case ten years ago” – not quite the pristine image traditionally associated with the Swiss Alps.

“They need a lot of water for the tourist industry and increasingly they are forced to filter the water,” he added, referring to Alpine resorts in cantons Valais and Graubünden.

Flooding too is expected to increase under the global warming scenario, with sudden deluges of rain forcing rivers to burst their banks and contaminate surrounding groundwater wells.

“It is a risk that is important but we really can’t foresee exactly what will happen. This has not been discussed in much detail yet,” said Pronk.

Nonetheless, experts appear to have several solutions at hand, some of which are already being employed.

Over the past ten years, scattered water treatment plants have been installing a technology where raw water is forced under pressure through polymer- or ceramic-based membranes, with a pore size of around 0.01 micrometres (µm; 1 µm = a thousandth of a millimetre – the width of a human hair is about 70 µm).

The process can remove minute particles such as suspended matter, bacteria, parasites and even viruses, according to Biner and the resulting drinking water is not only purified but also disinfected.

Experts and manufacturers also claim that the technology will cut back on the use of chemical additives such as chlorine or ozone, widely used in the current refinement process.

Once prohibitively expensive, the price of these membranes is becoming more attractive, says Biner. “In Switzerland, membranes are seen as a technology which has a big potential, especially in mountain areas.”

Some water treatment plants in Switzerland date back from the Second World War and Pronk reckons the time is ripe for change. “This would be a very efficient upgrade,” he said.

However, while Eawag and SGWV provide technical advice to the plants (some are privately owned), it’s down to each individual canton and often municipality to decide on implementation.

If no one is really sure what the future in Switzerland will look like under the influence of climate change, Professor Andrea Rinaldo, director of the ecohydrology department at the federal institute of technology in Lausanne, feels that the country possesses the know-how and will to adapt.

“The most important thing is that the scientific community is aware of the problem and that they communicate it to the government. It happens very fast here, if there’s one community that would succeed in this scenario then it would be the Swiss,” he told Swisster.

“If you look at our geographical situation then we should be okay,” speculated Biner. “But only if the rainfall patterns remain more or less as they are now.”

“We have also been thinking about how to collect water. And perhaps take it from dams that are already there, filtering it with this membrane technology,” he said.

Swiss federal climate change policies