The provision of good quality water in sufficient quantity is a basic need for the society. According to the data of Hungarian Investment and Trade Agency the total water abstraction in Hungary is about 6,000 million m3/year, of which 75% is used in power plants as cooling water. Within the remaining part, 40% is residential use, industry takes one quarter and agriculture uses the rest (irrigation 15%, fishponds 5% and animal breeding 15%). All settlements, more than 94% of households in Hungary are connected to the water supply system.
Particularly two extremities of the precipitation pattern, namely, intense rainfalls and drought/reduced precipitation can cause the most damage to the drinking water supply system. The quality of all types of water bodies can be harmed by intense precipitation. Intense precipitation – both in the form of storm runoff and resulting floods – can mobilise not only nutrients, but other pollutants such as salts, fecal coliforms, pathogens, heavy metals and various chemicals and wash them into the water bodies.
Beside the aridification trend of Hungary, higher temperatures (which reduce precipitation and increase the evaporation rate from water surfaces) decrease natural storage of water. Given that 95% of the surface waters of Hungary arrives from abroad, it is important to note that in case the neighbouring countries increase their storage capacities, reducing water flow arriving to Hungary.
The foreseen higher air temperatures and lower rate of runoff are expected to increase surface water temperatures, accelerating the rate of bacteriological processes and chemical reactions within the water. Eutrophication can deteriorate water quality by changing the transparency of water, the levels of dissolved oxygen concentration and pH, which can have adverse effects on the ecosystem function as well as human health and safety, recreational activities and water treatment processes.
More frequent heavy rains may cause the overload of the sewage system (if rain water stream in it), and in case of undersized systems, wastewater can overspill at wastewater pump stations and filter into the drinking water.
In an urban environment, sealed surfaces influence the infiltration in two directions: on one hand, they prevent the rain water filtering down to the soil and the water intake plant underneath. On the other hand, by holding back, this liquid gets accumulated and its runoff becomes more intensive, which may damage built infrastructures and vehicles as well.