4.7 Residential Consumption 4.8 Residential Consumption – connections to mains supply 4.9Residential consumption - public water points Shows the average water consumption of groups of people B.2 Discussion Theoretically the “best” water consumption indicator is expressed in terms of litres/person/day. However there are data problems. Particularly: lack of accurate total consumption data (for example from universal metering) poor quality, or out of date, census data While the accuracy of service populations may need improvement, utilities are often more confident in the number of connections in their system. In addition water production figures may be known more reliably than those for water consumption. To draw on these other sources of (potentially) more reliable data a number of indicators have been included. These will allow trending analyses to be undertaken within a utility. Inter utility comparisons will be more difficult, however, given the different mix of household sizes and dwellings served by one connection. This is especially the case between utilities in different countries. Homogeneity of household size, and dwellings per connection, within a country will allow informed in-country comparisons to be made. C. Non Revenue Water C.1 Indicators INDICATOR UNIT CONCEPT Non Revenue Water Non Revenue Water Non Revenue Water % m3/km/day m3/conn/day Difference between water supplied and water sold expressed as a percentage of net water supplied; as volume of water “lost” per km of water distribution network per day; and volume of water “lost” per water connection per day. C.2 Discussion Non revenue water represents water that has been produced and is “lost” before it reaches the customer (either through leaks, through theft, or through legal usage for which no payment is made). Part of this can be saved by appropriate technical and managerial actions. It can then be used to meet currently unsatisfied demand (and hence increase revenues to the utility), or to defer future capital expenditures to provide additional supply (and hence reduce costs to the utility).
The number of pipe breaks, relative to the scale of the system, is a measure of the ability of the pipe network to provide a service to customers. The rate of water pipe breaks can also be seen as a surrogate for the general state of the network, although it reflects operation and maintenance practices too. It must be recognized, however, that highly aggregated reporting can hide the fact that sections of the network may be perpetually failing, whilst much of the remainder is in reasonable condition. Break rates for different materials, diameters or time periods laid can show where breaks are concentrated. Sewer blockages are, likewise, a measure of the ability of the sewer network to provide a service to customers. Blockages can reflect a number of issues including the effectiveness of routine operations and maintenance activities, the hydraulic performance of the network, and the general condition of the pipes. Bursts include failures on mains, service pipes where they are the Utility’s responsibility, or at joints or fittings, that are found by visible signs of water, not through leak detection by Utility staff. Sewer blockages include all blockages or collapses that occur in sewers or drains that are the Utility’s responsibility, whatever action is needed to clear them. F. Operating Costs & Staff F.1 Indicators INDICATOR UNIT CONCEPT 11.1 Unit Operational Cost W&WW 11.2 Unit Operational Cost W&WW US$/m3 sold US$/m3 produced Total annual operational expenses1/Total annual volume sold. Total annual operational expenses1/Total annual water produced. 11.3 Unit Operational Cost – Water only 11.4Operational Cost Split - % Water 11.5Operational Cost Split - % Wastewater 11.6 Unit Operational Cost – Wastewater US$/m3 sold % % US$/WW pop served Annual water service operational expenses1/Total annual volume sold. Split of the total cost into water and wastewater Annual wastewater operational expenses1/ Population served 12.2 Staff W&WW/’000 W&WW conn. 12.1 Staff W/’000 W conn. 12.5 Staff WW/’000 WW conn #/’000 W&WW conn #/’000 W conn #/’000 WW conn Total number of staff expressed as per thousand connections