Water Leakage Monitoring & Reduction

WATER LEAKAGE MONITORING & REDUCTION

How real time water network monitoring reduces leakage

4 BASIC METHODS OF LEAKAGE CONTROL

Sometimes known as ‘Squeezing the Box’

The different types of leakage in the water distribution network each have different impact and a different economic cost to remedy. The overall run-time of leaks consists of awareness, location and repair times (see opposite).

Long leakage run-times generate large water losses, even from relatively small leaks.

The four basic methods for managing real losses are:

1) Pressure management – reducing excess pressure, reduces the volume of water lost through leaks (including customer-side leaks which are estimated to account for around 25% of overall leakage). Lowering or stabilising pressure also helps to reduce bursts by putting less ‘strain’ on the infrastructure.

2) Active Leakage Control – the process of proactively looking for un-reported leaks and bursts, this consists of two distinct stages:

  • Leak monitoring and localisation.
  • Leak location and pinpointing.

3) Speed and quality of repairs – a rapid & efficient response to reported leaks that sends teams to the correct location.

4) Pipe material selection, installation, maintenance, renewal and replacement – asset renewal to reduce the rate of occurrence of new leaks, and investment in facilities such as district meter areas (DMAs) and telemetry to improve the efficiency of Active Leakage Control operations.

The combined action of these four control strategies is sometimes known as ‘squeezing the box’ (see opposite) because they focus on reducing the rate of leakage towards a ‘Sustainable Economic Level of Leakage’. This is defined as the level at which fixing a leak is less than the cost of not fixing the leak – which includes environmental damage and the cost of developing new water resources to compensate for the water lost through leaks.

The use of telemetry to monitor the network helps determine that level and is essential to implementing these water leakage reduction strategies.

How does telemetry help?

It greatly helps with the formation of district metered areas (DMAs) which make it possible to divide the water distribution network into small, isolated, and independent water distribution networks. Within the DMA the quantities of water entering and leaving the area are controlled using the closure of metered valves, the values are reported and the valves are controlled with telemetry and SCADA systems.

A permanently monitored DMA is the most effective tool to help reduce the duration of unreported leakage. Monitoring night flows is used to identify unreported leaks, and provides data required to efficiently locate them.

Telemetry is also used to manage water pressure using valve and pump controls. Small reductions in average and maximum pressures over large areas are usually more beneficial in reducing burst rates, on both mains and services, than large pressure reductions over small areas.

water loss reduction
leakage control strategies

4 basic leakage control strategies – source: D Pearson

 

rsr.akro.org ProjectUpdate Crop 600

Summary of DMA implementation for leakage reduction in Kenya – source: Nouri Koedam
Minimum Night Flow recoverable loss source EPAL active water loss contol 600 Minimum Night Flow analysis to target recoverable loss – source: EPAL

DISTRICT METER AREA MONITORING

How DMA’s help control leakage

As the illustration opposite shows establishing and using District Metered Areas to reduce leakage, also referred to as Non Revenue Water (NRW) reduction, uses the same guiding principles but becomes a unique implementation for each Water Service Provider due to variations in customer metering, usage, topography, pipework network layout etc.

By grouping and aggregating data stored in an analytic software application, district metering can be performed via the following steps:

  1. Identify the meter or meters that feed water into the district (i.e., the “master meter”).
  2. Identify the group of meters in the district and aggregate the total consumption of these meters on an interval-by-interval basis. Accrue the aggregated consumption of the district into a virtual meter.
  3. Compare the net consumption of the master meter (the measured input to the district) with the metered consumption of the aggregated district (the measured consumption within the district) on a time-synchronized interval-by-interval basis. Any difference between the net consumption of the master meter and the aggregated consumption of the virtual meter is considered , which can include leaks.

Once the district metering analysis has been conducted and the analytics application has ranked the various districts according to severity, water providers can prioritise where to look for leaks.

Where this includes large numbers of unmetered properties then best practice analysis of DMA flows requires the estimation of leakage when the flow is at its minimum, which is typically at night. Boundary valves around the DMA are closed and very accurate readings are taken at around 3:00 or 4:00am, which is generally the time when night flow is at its lowest. Customer demand is typically at a minimum at night and the percentage of the flow made up of leaks is therefore at its highest.

This enables water operators to accurately spot any unexpected continual increases in a DMA’s water consumption that might suggest a burst or an undetected leak, as demonstrated by the following diagram where a leak becomes apparent and then is fixed.

Fakenham Trend

WATER PRESSURE MONITORING

How controlling water pressure reduces leakage

A small reduction in pressure can mean a significant reduction in real losses through leaks. When activated during low-demand periods such as late at night or early in the morning, pressure management will not affect service levels and can reduce consumption in networks with no intermediate storage.

To effectively manage pressure, it is important to comprehensively evaluate a service area and gain an understanding of its background losses before introducing pressure control.

With a pressure management program, a utility’s distribution system is broken down into pressure zones. Pressure is monitored at the inlet, average zone point and the critical zone point. The average zone point is a location that exhibits the average pressure rate for the zone. The critical zone point is a location where pressure is the lowest, usually the highest elevation in the zone.

The reduction of pressure greatly reduces the amount of night flow when the system is quiet. Figure 3 shows how night flow is reduced in conjunction with the reduction in pressure. The reduction of night flow reduces a utility’s amount of leakage without even repairing a leak.

Effects of Water Pressure on Leakage

Effects of water pressure on leakage – source: Akdeniz University

Kidney Green

OUR MONITORING SOLUTIONS

Using the correct water leakage monitoring equipment is an essential component of a successful implementation leakage reduction programme. Accuracy is vital to avoid misleading analysis and the consequential waste of resources.

In addition, remote control of valves can save manpower cost and allow easier verification of leakage analysis over time.

Metasphere’s solutions allow the use of lower cost Point Green RTU’s for simple logging and remote reporting tasks through to Point Orange RTU’s for more complex analysis and reporting and finally MM-IM units for control and automation tasks.

FOR MORE INFORMATION ON WATER LEAKAGE MONITORING

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