Reducing non-revenue water:
an economic and environmental issue

Producing drinking water and delivering it to the consumer’s tap involves ever-increasing costs for pumping, chemical treatment and reservoir maintenance. The loss of any of this drinking water in the distribution network means producing even more to cover consumers’ needs. In addition to the financial loss for the operators, the environmental impact is not without consequences: more and more raw water resources are drawn from the water supply, more electricity and chemicals are consumed, which in turn lead to higher CO2 emissions. Acting on leaks and minimizing water loss is therefore a priority for local authorities across the world. While the efficiency targets in Western countries are as high as 85% (i.e., 15% water losses), in some countries the rate of non-revenue water is as high as 50%. With rates so high, it can be difficult for operators to be sustainable and even profitable in the long-term. In one of its studies, the World Bank estimates a global loss of 32 billion m³ of drinking water per year. Cumulative losses in developing countries account for more than half of this figure.

Non-revenue water is the difference between the produced drinking water entering the distribution system and the amount actually billed to water customers. Physical water leakage is not the only cause of non-revenue water volumes. In addition to leaks, there is also water used for service or fire purposes, tank overflows, non-accounted water and unauthorized connections. The main focus to reduce these water losses is on technology used for leak detection and to them locate these leaks.

District metering areas management, which consists of dividing the distribution network into small homogeneous sectors, allows operators to increase the number metering points between the reservoir and the customer. The difference between the inlet and outlet of each sector can indicate the volume of water lost. At each of these points, the operator can install a SOFREL DL4W data logger which continuously reads the meters or flowmeters, measures the pressure and performs a certain number of calculations (average, maximum flow rates, etc.). The data logger can also focus more precisely on the night flow rate which can help to identify any deviation in consumption at a time when it is supposed to be at its lowest. Since exceeding the threshold is often an indicator of water loss, the data logger sends an alert to the supervision and maintenance teams. This often occurs before there is any noticeable or visible loss of water. By reducing intervention time and directing the leak detection teams to the identified location, the SOFREL DL4W data logger can play a crucial role in the reduction of non-revenue water. The investment in the data logger is largely recovered soon after a first leak has been identified.

The SOFREL LS-V model, by regulating the pressure, can go further in the reduction of non-revenue water. Micro-leaks that cause continuous water loss are, due to their regular volumes, almost invisible in the curves. By controlling pressure, the SOFREL LS-V regulates valves and lowers water pressure at night, when the demand is lowest. During this period, the pipes in the network will be under less stress and the volume of such leaks will be reduced.