Analysis of apparent water losses, case study

Abstract

Apparent losses are the nonphysical losses that occur when water is successfully delivered to the customer but, for various reasons, is not measured or recorded accurately, thereby including a degree of error in the amount of customer consumption. According to data from the Lithuanian Water Supply Association, in 2012 about 124 mln. m³ of ground water was supplied to the network, but only 92 mln. m³ of it was sold, while the remaining share represented water losses – 32 mln. m³ per year. An average water loss level in Lithuania is 30%, varying from 53% to 15%. Local water utilities take a little care of apparent water losses, as they account for about 20–30% of the total water losses. This article deals with an investigation of apparent losses in Alytus city, Lithuania. The article highlights the significance of apparent losses and explains possible options for the control of these losses in order to recover revenue in systems with metered customers. One test was carried out with bulk water meters at blockhouses, using Class B and C water meters constructed sequentially. The other test was carried out at apartments of blockhouses, where new Class C flow meters are installed. Both tests showed a significant volume of apparent water losses due to inaccuracy of used flow meters. An average calculated pay-back period for the installation of Class C water meters is about 1 year.