The biggest investment that most water utilities will make is in their distribution system that they operate and maintain. Maintaining and upgrading this infrastructure is a required focus of the water utility, albeit an expensive proposition, since all water customers expect a safe, reliable and sustainable potable water supply and our water utilities are obliged to meet this expectation. Therefore, all water utilities must develop programs to track the performance of, manage and replace infrastructure as it is needed and ages. Insomuch as all infrastructure has a useful life, water loss control links directly to the timely, efficient management of infrastructure rehabilitation and renewable as a continuous process.
Infrastructure management involves the tracking of current and repaired pipelines, appurtenances, and customer service lines (on the utility side of the customer meter), as well as the expected repair and replacement schedule. This includes four key areas of activity:
Some specific improvements that water utilities should assess for implementation, especially those small organizations that are not required to provide distribution capacity for fire flows, include those in the following list. The chief purpose of these improvements is to assist the utility in detecting and isolating leaks, supporting leak repair without disrupting customer water use, and improving he overall reliability of the water distribution system.
Small water systems that do not have to provide capacity for fire flows typically lack looping or redundancy in their water distribution systems. However the water distribution systems are aligned with county and local roads which are laid out on a grid system. Creating looped systems by connecting distribution feeders will help to provide redundancy, and if leak repairs are needed, can allow the utility to isolate one run of pipe without eliminating service to those customers that reside beyond where the pipe repair occurs.
Isolation valving is used in conjunction with pipe loops to allow for the isolation of any particular pipe section. This equipment allows the water distribution system to operate even as pipe and leak repairs are implemented. In addition, isolation valving can be used to track leaks in small systems, and support line flushing and other maintenance activities. Isolation valving can also be valuable in supporting pressure management programs (by isolating zones, not creating head loss – see Pressure Management BMP); however, valving should not be considered a means to directly control system pressures, but rather a means to isolate different portions of the distribution system from one another as seasonal and other factors impact system operations.
District Metered Areas (DMAs) refers to placing meters on the water distribution system main lines at various locations throughout the distribution system in selected small zones within the distribution system such that monitoring and measuring water flow characteristics in different zones, or areas, of the water distribution system can occur. Integrating DMAs with master metering and customer meter reading programs can help detect leaks, and identify leak locations, since DMAs are typically placed in those portions of the distribution system that are more prone to leaks.
The data that should be tracked and archived to support infrastructure management was discussed previously in the water distribution data collection and management BMP. The methods that water utilities should employ to track and manage water loss (and leaks) are presented in the Leak Detection and Repair BMP. Budgeting for capital improvement projects and setting water rates appropriately are described in the BMPs for Facility Assessment and Capital Improvement Planning and Rates and Fees, respectively.
It is typically the best practice with DMAs to start with a small area or areas to determine the feasibility of the DMA, before proceeding with large or multiple DMAs.
Water Utility Infrastructure Management (joint industry organization)