Managing non-revenue water
Every second, critical resources are lost due to the high levels of non-revenue water in many regions of the world. Water loss is a worldwide challenge that has caused adverse effect to the economy and environment. Even more, that water needs to be produced and distributed. Imagine how our lives will be when water is lost before we realized that now is the time for us to manage our non-revenue water.
Water security is a must. We must preserve the limited supply of water for the sake of future generations and growing populations. Access for clean water is in many places taken for granted, just like the fresh air we breathe. We should always remember that water is a "product", and producing it is a comprehensive process. We are experiencing water scarcity caused by climate change, increase population, and lack of water management practices. We encounter a more subtle but significant issue when the distribution management is insufficient causing a water loss also referred to as non-revenue water, or NRW.
What is non-revenue water?
Non-revenue water (NRW) is water that has been produced and is "lost" before it reaches the end-user. Losses can be real losses through leaks, sometimes also referred to as physical losses. This is when the production costs and the energy used to produce and distribute the water are wasted. And when a significant amount of water is lost, it means that more water needs to be produced and once again be distributed.
What are the causes of non-revenue water?
The causes of water losses are many, ranging from leakages, pipe bursts and poor water management to illegal connections and unauthorized consumption.
Leakages and pipe bursts
A large portion of NRW is due to high volumes of clean water that are lost through leaks and overflow in the distribution system. There are many reasons for leakage such as corrosion, ground movements, or traffic load, in many cases, bursts have been triggered by high and fluctuating pressure, which could have been avoided by efficient pressure management.
Inadequate water management
In adequate water management of water resources contributes to water loss. This may, for example, be lack of maintenance of the supply network resulting in leakages and pipe bursts, or lack of customer meters, so that the utilities cannot bill the consumers based on actual consumption.
Unauthorized consumption
Unauthorized use of water such as water theft or filling a vacuum tanker from a fire hydrant not designated for that purpose, increases the volume of non-revenue water.
Dividing the supply network into district metering areas
Generally, NRW management in an open system is undertaken in a passive manner where NRW reduction activities are initiated only when the loss becomes visible or is reported. A more effective approach is to move towards Active NRW Management where dedicated teams are established and sent out to look for water losses, such as leaks, reservoir overflows, and illegal connections.
Active NRW Management is only possible using zones, where the system is divided into a series of smaller sub-systems for which NRW can be calculated individually. These smaller sub-systems, often referred to as District Meter Areas (DMAs) should be hydraulically isolated so that utility managers are able to calculate the volume of water lost within the DMA.
One effective method to prevent water loss is by dividing network into sections called district metering areas (DMA). Utility managers should create a thorough operations handbook specifically for each DMA to support upcoming groups in overseeing the water supply. The handbook of operations includes flow meter location drawings, a schematic of the pipe network, border and pressure control valves, as well as a copy of the invoice the DMA's database. The handbook is an operating guide and working document. A data, including details on the following, should be updated regularly:
- Flow and pressure graphs
- Leakage step tests data
- Leak locations
- Illegal connection locations
- Legitimate night flow (LNF) test data
- Pressure T Factor test data
Establishing a series of DMAs not only targets NRW reduction but it also improves asset condition and customer service by:
- Maintaining asset life through pressure management
- Safeguarding water quality
- Enabling continuous water supply
