Best Practice in Water Loss Control:
Improved Concepts for 21st Century Water Management
In 2003 the American Water Works Association (AWWA) adopted improved best practice methods for defining and measuring water loss in water distribution systems. This transition into a new era of effective water management marked a departure from previous terms and practices no longer useful to the industry. The following explains this departure from obsolete practices and articulates key points and best practices in water loss control today.
Improved Terminology: Non-revenue Water
In 2003 AWWA abandoned use of the term “unaccounted-for” water (UFW) because all volumes of water supplied within a distribution system go toward either beneficial consumption or wasteful loss. All water sent into the distribution system can be accounted for. Today, the industry term favored by AWWA and its Water Loss Control Committee when quantifying water loss is “non-revenue” water (NRW).
NRW is specifically defined to include the sum of specific types of water loss and any authorized, unbilled consumption that occurs within water distribution systems.
Enhanced Performance Indicators to Measure Progress
Although percentage indicators—typically the ratio of authorized customer consumption to distribution system input—still exist in the industry, AWWA discourages use of percentage indicators, such as the “unaccounted-for” water percentage. Using percentage indicators to assess water loss in distribution systems gives a misleading and unreliable measure of utility performance because a percentage indicator
❯ is greatly affected by changing levels of customer consumption
❯ cannot distinguish among the specific components of non-revenue water occurring in a distribution system
❯r eveals nothing about water volumes and associated costs (the two most important factors in assessing water waste within a distribution system).
Today, the industry best practice for water loss auditing created by the International Water Association (IWA) and AWWA now quantifies several key performance indicators, which provide vastly superior means for assessing water loss performance in distribution
systems, while recognizing that contributing factors and potential corrective measures are specific to each water utility.
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