Climate change scenarios indicate that there will be more water, especially in the western and northern parts of Sweden, while access to water will become worse in the south east, with an increased need for irrigation within agriculture as a result.
Dryer summers and changes to sea level are affecting both access to and the quality of drinking water. The risk of salt water entering water sources is increasing in coastal and low-lying areas, for example in Lake Mälaren. There is much to indicate that torrential rain is occurring more frequently, particularly in conjunction with warmer summers, which will increase the risk of pollutants entering our water sources.
In conjunction with increased precipitation, torrential rain and flooding, leaching of environmentally harmful substances from industrial areas, landfill and other polluted areas can increase. Increased leaching of nutrients and humus is also expected in the areas that receive more precipitation. Clear trends of increasing humus levels are already evident in many surface water sources, which places greater demands on purification in water treatment plants in these areas.
Torrential rain can lead to sewage treatment plants being forced to release raw sewage more frequently, which can affect both surface and groundwater sources. The drains used for sewage and surface runoff are often not of a sufficient dimensions for even the present circumstances, which becomes a more major vulnerability in the event of climate change. Landslides can also affects drinking water pipelines, which is why the pipelines must be secures when the risk of landslides increases.
Protection of water sources
The most serious threats to water quality are an increased spread of pollutants and increased microbiological risks in the event of flooding, torrential rain and increased water temperatures, altered odour and taste problems in both groundwater and surface water and the presence of toxic algae.
In order to maintain a satisfactory and secure supply of water in Sweden in the future, the protection of our water sources is becoming increasingly important. In those water sources where the microbiological and chemical risks are increasing, these must be dealt with in the water treatment plants, which places greater demands on the water treatment plants in terms of continual monitoring of changing water quality.
The risks of water-borne infections via parasitic protozoans and viruses is judged to be higher now that when the majority of our water treatment plants were built. In general, our current water treatment plants were constructed in order to deal with bacteria, not viruses and parasites.
The doses of chlorine used in Sweden are largely ineffective against parasites and have a moderate effect on viruses. In other words, we need to make use of new technology. Possible measures are strengthened protection of raw water, supplementary disinfection with UV, ozone or membrane filters and, in some cases, it may be pertinent to change water sources.