A storage tank that looks perfectly fine from the outside can be quietly degrading the water inside it. Chlorine residual fades, sediment settles, and in chloraminated systems, bacteria can start converting ammonia into compounds that were never supposed to be there — all without a single alarm going off on SCADA. Managing that risk is a core Class 2 responsibility, and it starts with two linked concepts: turnover and water age.
Tank Turnover and Water Age
Water age is the length of time water has been sitting in a tank (or anywhere in the distribution system) since it entered. Turnover describes how completely and how often a tank's stored volume is cycled out and replaced with fresh water. A tank with good turnover exchanges most of its volume regularly as part of normal system operation; a tank with poor turnover has water that sits for extended periods with little exchan