Both underground and surface water from lakes and rivers are used as drinking-water in the capital city of Latvia, Riga, which has a population of 1 million. The technological process of water treatment is different in every water intake station, and the water quality is still judged according to the former Soviet Union`s standard norms. Costing of drinking water consumption and metering of sewage water, is an approximate procedure because it is based on the consumption of electric power and adjusted by a special correction coefficient for each pumping station. It is a complicated task to find out the efficiency of the pumping stations without flow-meters. Pressure in pump units is mostly controlled by a gate valve installed in the pressure pipe.