Section PSC 185.85 - Water audits and water loss control(1) DEFINITIONS. In this section: (a) "Apparent loss" means the volume of water attributable to customer and station meter inaccuracies, billing and data transfer errors, unauthorized consumption, and theft.(b) "Authorized consumption" means the volume of water used by metered and unmetered customers and the volume of water used for other purposes that is implicitly or explicitly authorized by the utility, including water used for flushing water mains and sewers, fire protection and training, street cleaning, public fountains, freeze prevention, and other municipal purposes regardless of whether the use is metered.(c) "Non-revenue water" means the volume of water equal to the difference between the volume of water entering the distribution system and the volume of water that is sold.(d) "Real loss" means the volume of water attributable to leaks and losses in the pressurized distribution system up to the customer meter, including water lost due to main breaks, service breaks, and tank and reservoir overflows.(e) "Revenue water" means the volume of water entering the distribution system that is billed and for which the utility receives revenue.(f) "Unaccounted-for water" means the volume of water entering the distribution system for which a specific use or purpose cannot be determined.(g) "Water loss" means the difference between the volume of water entering the distribution system and authorized consumption. Note: Water loss equals the sum of real and apparent losses that are caused by unauthorized consumption, meter inaccuracies, accounting errors, data processing errors, leaks in transmission and distribution mains, leaks in service connections up to the customer meter, seepage, overflow, evaporation, theft, malfunctioning distribution system controls, and other unaccounted-for water, as described in the American Water Works Association M36 manual - Water Audits and Water Loss Control Programs.
(2) UTILITY PRACTICES. A public utility shall do all of the following: (a) Meter all water uses and sales, where practicable.(b) Maintain and verify the accuracy of customer meters.(c) Maintain and verify the accuracy of station meters.(d) Identify and repair leaks in its distribution system to the extent that it is reasonable for the public utility to do so.(e) Control water usage from hydrants.(f) Maintain a continuing record of system pumpage and metered consumption.(g) Conduct an annual water audit under sub. (3).(3) WATER AUDITS. (a) A public utility shall conduct an annual water audit on a calendar year basis and submit the results of the audit to the commission no later than April 1 of the subsequent year.(b) A public utility water audit shall include the measured or estimated volume of all of the following: 1. Water purchased or pumped from all sources.2. Water used in treatment or production processes.3. Water entering the distribution system.4. Water sold, including both metered and unmetered sales.5. Water not sold but used for utility-authorized purposes, including flushing mains, fire protection, freeze prevention, and other authorized system uses.7. Unknown or unaccounted-for water.(c) The components of a water audit are shown in Table 1. Table 1. Water Audit Components
System Input Volume (Finished Water + Purchased Water) | Authorized Consumption | Billed Authorized Consumption | Billed Metered Consumption (including water exported, wholesale sales) | Revenue Water |
Billed Unmetered Consumption (Bulk water sales, utility uses) |
Unbilled Authorized Consumption | Unbilled Metered Consumption | |
Unbilled Unmetered Consumption |
Water Losses | Apparent Loss | Unauthorized Consumption (Theft, uncontrolled hydrants, etc.) | Non-revenue Water |
Metering Inaccuracies (Customer, station meters) |
Data Handling Errors |
Real Losses | Leakage on Transmission and Distribution Mains |
Leakage and Overflows at Utility's Storage Tanks |
Leakage on Service Connections (Up to point of customer meter) |
(4) WATER LOSS CONTROL. (a) Each public utility shall calculate its annual percentage of non-revenue water and its percentage of water loss, based on the volume of water entering its distribution system.(b) A public utility shall submit to the commission a water loss control plan if a water audit shows the public utility has any of the following:1. A percentage of non-revenue water that exceeds 30 percent.2. A percentage of water loss that exceeds 15 percent for a Class AB or Class C utility or 25 percent for a Class D utility.(c) A water loss control plan under par. (b) shall include all of the following: 1. The reasons for the excessive non-revenue water or water loss.2. A description of the measures that the utility plans to undertake to reduce water loss to acceptable levels within a reasonable time period.3. An analysis of the costs of implementing a water loss control program, including a comparison of lost sales revenue and the costs that would be avoided by reducing leaks and losses.4. Any additional information required by the commission.(d) The commission may require a public utility to conduct a leak detection survey of its distribution system if for three consecutive years the public utility's percentage of water loss exceeds 15 percent for a Class AB or Class C utility or 25 percent for a Class D utility.Wis. Admin. Code Public Service Commission PSC 185.85
CR 11-039: r. and recr Register July 2012 No. 679, eff. 8-1-12.