Industry standards suggest the maintenance and care of metal storage tanks. All metal storage tanks should be drained, cleaned, inspected and disinfected every three years and, where sediment is a problem, washed out annually. Regardless of a structure’s composition, however, all water storage facilities play a significant part in Total Coliform Rule compliance because of contamination risks and structure degradation.
State regulations vary in range and scope, with some requiring annual tank inspection but without the requirement that tanks be drained or cleaned. Some states require cleanings every three to five years. However, as responsible water utility personnel know, regular inspection and tank cleaning are critical to improving water quality and reducing treatment costs, both of which minimize customer complaints, unplanned expenses, and risks to public health.
Regular inspection and cleaning, with interim monitoring of inbound and outbound disinfectant levels, also make an operator’s life easier by reducing the likelihood of dirty water complaints, preventing quick loss of residual chloring, and helping forecast tank turnover problems.
Monitoring disinfection levels of water entering and exiting a pressure zone or storage facility is one of the simplest, most-effective ways to determine if cleaning is needed. Continuous monitoring systems, although expensive, may be one of the best investments a utility can make. Such systems provide immediate results to help personnel analyze any increased turbidity, fluctuation temperature, residual or total chlorine, and the need for operational changes or immediate on-site visits.
Contact one of Maguire Iron’s Field Representatives for assistance with evaluating your tank’s compliance with state regulatory requirements and industry standards.
Submitted by Chad “Eddie” Edwards, Maguire Iron Field Representative for Wisconsin
Ref: American Water Works Association Manual of Water supply Practices M42: Steel Water Storage Tanks