Water Supply Data Management, Infrastructure Planning & Asset Management

Peter Styles

Leakage ControlStrategy

Leakage Control

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Leakage Control - IWA Standard Water Balance

Network input

AuthorisedConsumption

Non RevenueWater

BilledWater

Losses

Billed and authorised

Unbilled but authorised

Apparent

Real

Billed and metered

Billed unmetered

Unbilled and metered

Unbilled and unmetered -•fire•flushing and jetting•parks and gardens•fountains

Unauthorised –•theft•Illegal connections

Other –•incorrect assumptions•billing errors•meter errors

Physical losses –•service reservoirs•transmission mains•distribution mains•connections•boosters

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Leakage Control

Non Revenue Water (NRW)

Unaccounted for Water (UfW)

‘Leakage’ = physical losses in the system

Any target needs to clearly define what it is targeting especially if it is a KPI

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Leakage Control

What are we lookingto control?

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Leakage Control

What are we looking to control?

•Water losses in treatment

•Losses in trunk mains and storage

•Losses in the distribution system

•Losses in private systems

•Strategy must address all of these

Metering is the key to knowing what to do

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Leakage Control - typical losses

Typical physical losses:

<1% from service reservoirs

3.0% from transmission mains

12.0% from distribution mains

<1% from operations

<1% from fire fighting

<1% stolen water????

7.0% from customer connections

3% from internal plumbing

Based on a system with total losses of around 25%

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Leakage Control

Water losses in treatment

Treatment losses are typically around 5 -10%

Measure abstraction and water put into supply – difference is treatment loss

Minimise treatment losses by good housekeeping and management at the treatment plant

Recycling can often be used

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Leakage Control

•Storage losses are often visible –prompt repair

•Trunk mains and all take-off points should be metered and logged

•Leakage may be visible from large mains – repair promptly

•Changes in metered use indicates possible invisible leakage

Water losses in trunk main and storage

Electromagnetic meter

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Leakage - Passive and Active Control

Passive Control•Repair bursts when they occur•Make repairs ‘as and when’

Cheap but high losses

Active Control

•Undertake pro-active interventions•Zoning and metering•Pressure control•Rehabilitation

Expensive but lower losses

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Leakage Control

Water losses in the distribution systems

An open system is difficult to model and to meter

Use DMAs to isolate supply zones

Each zone is metered

First priority is to have swift response to bursts involving isolation and then repair

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Leakage Control – Open System

WTP

Operators often think that open systems are easier to manage but leakage control is very difficult

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Leakage Control – DMA*s

WTP Trunk/supply main

DMA ‘B’

DMA ‘A’

Trunk mains require large metersDMAs require smaller meters

*District Meter Areas

District meter ‘A’ District meter ‘B’

Bulk supply meter

Bulk supply meter

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District meter ‘B’

Valving of all nodes is essential for leakage control

Leakage Control – Valves

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Leakage Control – DMA metering

Each zone is metered and data is logged

Differences in supply patterns can be seen from graphs using the logged data

Parts of the zone are then isolated and leaking pipes identified using listening devices

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Leakage Control - Pressures

Apartments

Very high pressure water main Connection

Russian system

Apartments

Lower pressure water main Connection

Mexico City system

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Leakage Control – Pressures

Each zone may have its own pressure control

Pressure zones are designed according to the contours and the need (e.g. height of the buildings and use of storage)

Pressure may be controlled by booster pumps or pressure reducing valves according to the need to raise it or lower it

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Leakage Control - Wastage

midnight

consumption

Mid daymidnight

Case study from South Africa

What was going on????

normal consumption

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Leakage Control - Wastage

This case involved a particular quarter of a city –the Chinese quarter.

There were many small laundry businesses who used standpipes which were left running all day.

Solution – a meter was put on each standpipe

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Leakage Control - Wastage

Wastage can also be high at facilities such as tanker filling points

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Leakage Control – New Works

Zones are constructed with metering and all junctions valved

Any cross links to other areas must be valved and metered

Materials and jointing are crucial:

•Plastic is excellent but joints must be good•Steel is short lived due to pin holing

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Leakage Control – Programming

A leakage control strategy requires a program which includes:

•Bulk meter installation•Treatment plant audit•Trunk main surveys and audit•Setting up of DMAs•Checking of the DMAs and remedial actions•Pressure control•Use of appropriate materials•Isolation and repairs to bursts•Action on private (internal) systems

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Source: IWA

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Leakage Control – Resume

•Minimise treatment plant losses•Eliminate trunk main losses•Reduce distribution system losses•Use DMAs for metering and monitoring•Use best materials for pipelines and ensure joints are high quality•Install pressure control•Make prompt repairs for bursts•Take action on inadequate private systems

A new report and guide for the detection of water pipe leaks has been published by UKWIR - "A SURVEY OF PRACTICES FOR THE DETECTION AND LOCATION OF LEAKS". This new 77 page report collates the practical experience of 9 UK Water Companies. It provides a software tool to guide the engineer towards the most appropriate method, using:

• Volume Saving• Type of Increase• Pressure• Properties (residences)• Connection Density• Mains Material• Pipe sizes• Water Quality Risk• Traffic Management Constraints• Ambient Noise Level• Sub-metering Options• Permanent logging option

The system provides a banded score for Equipment / Technique selection. The report will be of most interest to practitioners and managers responsible for managing leak detection.

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Leakage Control – New Manual