In the water distribution system, cold weather can create risks that are hidden from plain sight: ice accumulation inside water storage tanks. Often, when operators realize they have a problem with ice buildup in their tanks, the tank’s interior is already damaged or the wall is punctured. Additionally, traditional methods for reducing ice formation inside water tanks have been expensive, difficult and often only partially effective.

Water operators in Anchorage, Alaska, struggled with ice formation in their 1-million-gallon steel tank for years. After discovering significant damage to the tank’s coatings and central column that supports the roof, operators at the utility researched various solutions. They decided upon a novel approach that would address ice formation once and for all: active mixing. After installing a PAX Water Mixer in September 2010, the tank remained ice-free during the winter despite outside temperatures of -15° F to -20° F. 

Active submersible mixers are a new approach for managing ice formation inside water storage tanks. Active mixers push the heavier, warmer water at the bottom of the tank up to the top and keep the entire contents of the tank thermally uniform, preventing ice formation. But only the most powerful active mixers are able to keep a tank ice-free all winter long. With the benefits of active mixing becoming better known, more municipalities are adding mixers to all of their tanks – especially to provide freeze protection during the winter.

A) Standpipe with active tank mixer                               B) Standpipe without active tank mixer