All the way from the dam to the Jesenice reservoir tanks, the flow of water is monitored and regulated from a central control room. The operators keep track of everything, from the status of the various technologies and the increasing quality of the water in the treatment process, to the quantity of water delivered to individual supply lines. Water is under constant control throughout its entire journey.
The towns of Zruč nad Sázavou, Ledeč nad Sázavou, Světlá nad Sázavou, Havlíčkův Brod, Čechtice, Humpolec, Pelhřimov and Pacov are supplied with water directly from the treatment plant. The supply tunnel, on the other hand, is used to carry water to Trhový Štěpánov, Vlašim, Divišov, Čerčany, Benešov, Velké Popovice, Jílové, Davle, Luka pod Medníkem, Týnec nad Sázavou, Jesenice and Průhonice. From the Prague water supply system, water is sent on to Říčany, Roztoky, Beroun, Černošice and other communities in the Central Bohemia region. The operators adjust the treatment plant’s output according to water demands.
The control room operators always keep an eye on two aquariums. These contain young rainbow trout, which react to the quality of the reservoir water flowing continuously through their tanks. If anything was wrong with the water, the fish would start behaving differently and the treatment plant operators would take appropriate action.
But this is not the only situation where fish can help with water quality. The mix of fish species in the reservoir can influence the quality of the water drawn from it. For this reason, we use managed stocking to keep its population of predatory and plankton-eating fish in an optimal equilibrium.
At the end of the entire treatment process, chlorination of the water protects against the proliferation of micro-organisms and their effects. This is a kind of “preventive disinfection” step for the journey to the consumer. The chlorine is released from the water only gradually, and keeps working for a fairly long period of time, but it doesn’t stay in the water forever. Before it enters Prague’s distribution system, this protective dose is therefore repeated at a level sufficient to ensure it reaches our homes safely. Chlorine isn’t harmful to health in the quantities used for drinking water. The amount added is really very small.
The Želivka Water Treatment Plant was inaugurated on 25 May 1972. In its first phase of operation, a production capacity of 3,300 m3/s was sufficient to supply Prague, and was handled by a coagulation tank together with sand filtration. In the next stage of its development, which was completed in 1987, the treatment plant’s capacity was more than doubled. The raw water pumping station below the dam was expanded, and a new discharge line, a new filtration hall, chemical dosing facilities and a new chlorination plant were built. As a result, by 1987 the Želivka Water Treatment Plant had reached a maximum capacity of 7,000 l/s of raw water. At the time of its completion, it was the largest water treatment plant both in Czechoslovakia and Europe as a whole.
... if milky, cloudy water comes out of your tap, that’s not because of chlorine, but oxygen bubbles? The chlorine already evaporated a long time ago.
If you’d like to learn more, continue to the other parts of the treatment plant...
