Unaccounted for Water

From Water Wiki

Years ago two kids named Jack and Jill were responsible for providing water to their household. They were sent on a mission to fetch a pail of water. In the fated case we all know about, poor Jack ended up injured and all the water he had collected was lost. We can assume that even under the best of circumstances, Jack and Jill would have lost some water through inevitable spillage as they ran down the hill. If they had not been maintaining their pail correctly, the leakage through cracks may have been substantial. On a hot sunny day, Jack or Jill might be tempted to stop and drink from the pail to quench their thirst. Jack might argue that his drink of water was necessary for the successful completion of his mission, but if he did not acknowledge the drink, his family could easily have assumed that this water had spilled on to the ground through his carelessness. Tracking water even in Jack and Jill’s time was a complicated matter.

While very few communities depend on small children for their water needs, getting water from streams, lakes and wells into people’s homes in a form that they can use still involves many steps and many opportunities for losses along the way. As water has become more valuable, water providers have improved their ability to track and minimize waters losses. In 1997, the International Water Association formed a multi-country task force to develop a uniform methodology to track water losses. http://www.awwa.org/Resources/content.cfm?ItemNumber=588

Despite the existence of an international methodology, utilities continue to use different methods to track their water losses and comparing water loss information across utilities can be difficult and/or misleading. For example, one utility may calculate unaccounted for water as a percent of the water they withdraw from their water source, while another utility calculates unaccounted for water as a percent of the water leaving their treatment facility (as much as 15 to 20 percent of water withdrawn from sources may be consumed in the process of treating water (eg. Backwashing filters).

It is important to recognized that "Unaccounted for water" does not equate to "leaks." Water can be "unaccounted for" because of faulty meters and use for purposes that aren't metered, such as firefighting, fire training, and washing filters at the water plant.

In 2006, the North Carolina Rural Center carried out a comprehensive utility water and sewer survey that included questions on water usage. The survey asked utilities to quantify their “Annual Usage” over the last 12 calendar months and to estimate their monthly “Unaccounted for Water” usage. 466 water utilities provided information on their unaccounted for water as part of this survey. Based on this data, the average amount of unaccounted for water as a percent of water usage was 12%. The numbers below show the distribution of unaccounted for water across the State of North Carolina.

<1%: 30

1.1 - 5%:113

5.1 - 10%:114

10.1 - 15%:64

15.1 - 20%:61

20.1 - 25%:28

25.1 - 30%:19

Over 30%:37