Assessment of apparent losses in urban water systems

Abstract

Apparent losses relate to water that is consumed but not paid for. Most research carried out in the last decade particularly in the United Kingdom focused mainly on leakage. Until now, there are no set procedures and guidelines for assessment of apparent losses. Much work remains to bring it to par with the available tools and methodologies for leakage management. In the absence of adequate data and proper methodology, most developed countries use default values, which tend to be lowest values for well-managed water systems, for computation of apparent losses. These may not be appropriate for developing countries. This paper presents a methodology for the assessment of different components of apparent losses based on field audit and operational data for Kampala city's water distribution system in Uganda. Metering inaccuracies and illegal use have been found to be significant components of apparent losses. Appropriate intervention strategies have been developed based on the assessment.

Residential water meter selection using the analytical hierarchy process

“…The preference ratio was 4.66, implying that the multijet meter was 4.66 times more preferred than the single-jet water meter. These studies support the final ranking results for KWDS, which often has particulates in the water, especially in the older parts of the network, and where about 40% of all residential water consumption occurs at low-flow rates < 100 L/h (0.4 gpm; Mutikanga et al, 2011a). The accuracy-degradation rate criterion was considered to be more relevant than other criteria according to comparative expert judgment (Table 1).…”

“…About 70% of the meters are the oscillating-piston type. In a study carried out in Kampala (Mutikanga et al, 2011a), the global weighted domestic meter accuracy was estimated at 78.5±0.9%, meaning that meters are underregistering consumption by 22% and resulting in significant Wrongly selected meters can lead to early failure, high accuracy-degradation rate, early meter replacement, and substantial loss of utility revenues. revenue loss to the utility.…”

“…According to the annual water audit (fiscal year ending June 2006) for the City of Philadelphia, Pa., customer meter inaccuracy was estimated at 0.4 × 10 6 m 3 (105.8 mil gal) costing the utility more than US$0.5 million in revenue (AWWA, 2009). In Uganda's capital city of Kampala, about 22% of domestic water consumed is not measured because of metering errors (Mutikanga et al, 2011a). Annual metering inaccuracies have recently been estimated at more than 8.7 × 10 6 m 3 , costing the utility about US$7 million (Mutikanga et al, 2011b).…”

A Parameter Classification System for Nonrevenue Water Management in Water Distribution Networks

“…Losses can be real losses (e.g., via leaks, sometimes also referred to as physical losses) or apparent losses (e.g., via theft or metering inaccuracies) [24][25][26]. NRW corresponds to water loss due to leaks, commercial problems, and nonbilled consumption such as a lack of water meter precision or mistakes in client databases.…”

“…Advances in Civil Engineering e IWA recommends the use of alternative indices such as water losses per junction and per main length and infrastructure leakage indices [11][12][13][24][25][26][27].…”