American filters are used for rapid filtration after settling. The water is collected in clean water reservoirs where chlorine is then added. Water quality is monitored for more than 200 components. There are 23 indicators for drinking water, including measurements of hardness, turbidity, and residual chlorine. State standards for drinking water set under the former USSR are still being used and are generally lower than in the United States.
Nitrates are usually higher in underground water.
Fluoride occurs naturally in the water, so it is not added. Tashkent sits about 20 miles downstream from the industrial city of Chirchik. With many chemical plants in the area, heavy metal contamination of Tashkent's water supply must be a problem. Because of the lower, older, USSR state standards, levels of lead, mercury and others may be higher in Tashkent's water supply than they would be elsewhere in the world. Extensive displays of water fountains and trees occur throughout the city.