In this module you will hear about how dividing a large urban area’s water supply into zones – District Metering Areas (DMAs) – can help optimise network efficiency. This can result in considerable operating and maintenance cost savings, for example by locating and reducing leakage. 

The distribution pipe network in cities is often divided into zones to get a better understanding and control of pressure, flow and leakage. We call these zones District Metering Areas or DMAs. 

To create a DMA, valves within the distribution pipe network are closed. A few pipes remain open to supply and remove water from the DMA. These are fitted with flowmeters to record the flow in and out. With the addition of consumer meters, the amount of water billed to the consumer in the area can be measured against the amount of water supplied to the DMA. "

The difference between the two figures is called Non-Revenue Water or NRW. The NRW represents the water volume not accounted for.

This can be due to non-metered consumption, pipe leaks, fire hydrants, stolen or illegal connections, and metering inaccuracy. 

Pipe leakage in networks typically represents 90 % or more of the NRW."

In addition to measurement of flow in and out of all zones making it easier to localise leaks, you can also regulate the pressure in each zone and achieve leakage reduction. Depending on the variation of terrain elevations, the distribution network can be divided into pressure zones. This is done to avoid pipes in lower ground having higher pressure than needed, and pipes in higher elevations having insufficient pressure to satisfy consumers.

Pressure and leakage are directly related. The higher the pressure, the higher the leakage. So, the key is to provide a constant minimum pressure while maintaining consumer satisfaction. Pressure-reducing valves (PRVs) and booster pumping stations can be used to control pressure in areas of the network.

To find out more about how to achieve an optimal pressure management, see Module 3.

Some of the other benefits include longer-lasting pipelines, lower energy consumption and fewer pipe bursts.

In addition, due to the increase in data obtained from zoning, operational efficiency and asset management are also improved. This is because you can actively use data-driven analytics to get alerts of leakage events, for example, or to predict the probability of a pipe failure.

Let’s recap what we have presented in this module:

• How network zoning or DMAs can help identify water loss and localise leaks

• How network pressure zoning and pressure reduction can help reduce the leakage

• How operational efficiency and asset management can be further enhanced by actively using data from network zoning