Water meter replacement and its impact on water consumption, utility revenue and payback periods

Mechanical water meter accuracy degrades over time due to wear and tear. Based on this premise, many water utilities around the world undertake meter replacement projects. In many instances, these projects neither assess the potential or actual impacts of meter replacement on consumption and utility revenue, nor undertake meter replacement based on a best practice, customised metering policy. From 2013 to 2015, Johannesburg Water (SOC) Limited embarked on a project to replace more than 50 000 mechanical water meters that had not been read over a period of 180 days due to technical faults. This study obtained and analysed two databases of these meters and arrived at a sorted and validated database comprising 3 679 meter replacements. For each meter replacement, twelve months of water consumption data was obtained for the period prior to and after replacement. This study then investigated the impact of replacement on water consumption, utility revenue and payback periods. Some high-level highlights from the study include the following: (i) a metering policy that addresses such issues as efficient meter database management, and the optimum meter replacement age and/or volumetric reading, is critical for any water utility if it is to obtain the best results from meter replacement; (ii) in order to guarantee the highest returns on investment, bulk meters (40 mm and larger) should be prioritised for meter replacement over single-stand residential meters; (iii) the replacement of 20 mm and 25 mm meters with 15 mm meters resulted in more accurate metering of consumption by virtue of increased consumption; and (iv) payback of the 15 mm replacement mechanical meters was achieved within 12 months, with the replacement of 20 mm and 25 mm meters resulting in average monthly revenue increases per property of R266.70 and R203.08 respectively.