Record-setting heat waves are sweeping the country this summer, placing higher-than-usual demand on water utilities. High water use by consumers typically translates into high turnover in water storage tanks, giving water less time to age and stagnate within the tank. However, areas with large capacity tanks or low summer demand can suffer from thermal stratification inside water storage tanks and serious water quality problems.
Thermal stratification – or the layering and separation of different water temperatures – can create high water age, loss of residual disinfectant and taste and odor complaints from customers. Water entering the tank during the fill cycle is typically much colder than water already sitting in the tank, which has been warmed by the sun. The cold water will remain on the bottom of the tank while the warmer, more buoyant water floats to the top of the tank for many days.
Active tank mixing can eliminate thermal stratification in storage tanks by ensuring that water entering the tank is completely circulated with the rest of the tank’s volume. Consistent water temperatures throughout the tank mean that residual is consistent as well. An added bonus is that homogenous water temperatures lower headspace temperatures and reduce corrosion rates inside the tank.
To learn more, watch our video on thermal stratification and active mixing: