Introduction – Pressure
Management As Foundation
Of Effective Leakage Management
Bambos Charalambous
Pressure Management
Questions
o Is it really necessary?
o Where can it be applied?
o How does it work?
o Is it reliable?
o Are there any limitations?
…More Questions
o What are the benefits?
o Are there any disbenefits?
o Has it been proven?
o Is there sufficient knowledge?
o Can it be fine tuned?
o How does technology assist? 2
Pressure Management:
IWA Water Loss Specialist Group Definition
In its widest sense, Pressure Management can be defined
as the practice of managing system pressures to the
optimum levels of service ensuring sufficient and efficient
supply to legitimate uses and consumers, while:
 reducing unnecessary excess pressures,
 eliminating transients and faulty level controls,
all of which cause the distribution system to leak
unnecessarily
Effective Pressure Management
“is a measure of the extent that the targeted objectives of
a water utility’s pressure management programme are
achieved”
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EU Reference Document
Good Practices on Leakage Management
WFD CIS WG PoM (January 2015)
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Excerpts from the EU Reference Document
Good Practices on Leakage Management
Pressure Management
•“Pressure strongly influences burst frequency and leak
flow rates on mains and service connections, …”
•“The basic foundations of effective leakage management
are the management of excess pressure and pressure
transients, …...”
Recommendation R:
“Pressures must be measured and monitored; excess
pressures and pressure transients must be managed
and reduced wherever feasible, ……”
Recommendation S:
“The sequences in which pressure management, active
leakage control, leak repairs and pipe replacements are
carried out is very important, if wasted expenditure is to
be avoided.”
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Excerpts from the EU Reference Document
Good Practices on Leakage Management
Several underlying concepts and factors have contributed over the past 20 years to
success stories in reducing and controlling leakage at acceptable levels:
 District Metered Areas to identify and target leaks where and when they occur.
 Influence of pressure on leak flow rates of different types of leaks (FAVAD
concept).
 Component analysis of background leakage, reported leaks and unreported
leaks.
 Standard IWA Water Balance, terminology and best practice performance
indicators.
 Improved technology for leak detection.
 Understanding how pressure influences burst frequencies of mains and
services.
 Economic ALC intervention, with or without Pressure Management.
 Enormous improvements in ease and speed of on-site data collection and
transfer.
 Innovative pressure control technologies to modulate and stabilise pressures.
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Excerpts from the EU Reference Document
Good Practices on Leakage Management
Leakage management is now becoming a maturing
technical subject which requires a professional
approach – the days of ‘guesswork’ or ‘let’s try this
and see what happens’ are numbered, although not
everyone realises that yet. However, whatever the
type of leak – background, reported or unreported –
the basic foundations of effective leakage
management are the management of excess
pressure and pressure transients, and limiting the
run time of all detectable leaks, whether reported or
unreported.
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Managing Real Losses
Secondary
Influence
Secondary
Influence
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Leakage Increases with Pressure
(L1/L0)=(P1/P0)N1
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Burst Frequency Increases with Pressure
Mains Bursts [per 1000 Km / year]
400
300
200
100
0
0
10
20
30
40
50
60
70
Average Night Pressure [m]
Source of Data: Welsh Water
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Pressure: Burst Frequency Relationships
Country
Australia
Bahamas
Bosnia
Herzegovin
Brazil
Canada
Colombia
Cyprus
Brisbane
Number of
Pressure
Managed
Sectors in
study
1
Assessed
initial
maximum
pressure
(metres)
100
Water Utility or
System
Gold Coast
10
60-90
Yarra Valley
New Providence
4
100
7
39
Gracanica
3
50
Caesb
2
70
Sabesp ROP
1
40
Sabesp MO
1
58
Sabesp MS
1
23
SANASA
1
50
Sanepar
7
45
Halifax
1
56
Armenia
25
100
Palmira
Bogotá
5
2
80
55
Lemesos
7
52.5
Bristol Water
21
62
United Utilities
10
47.6
1
1
1
112
Maximum
Minimum
Median
Average
Average
Average
69
130
199
England
Torino
Italy
Umbra
American Water
USA
Total number of systems
199
23
57
71
Average % Average
reduction
%
Mains (M) or
in
reduction
Services (S)
maximum
in new
pressure
breaks
35%
28%
M,S
60%
M
50%
70%
S
30%
28%
M
34%
40%
M,S
59%
M
20%
72%
S
58%
M
33%
24%
S
30%
38%
M
80%
M
65%
29%
S
64%
M
30%
64%
S
50%
M
70%
50%
S
30%
M
30%
70%
S
23%
M
18%
23%
S
50%
M
33%
50%
S
75%
94%
M,S
30%
31%
S
45%
M
32%
40%
S
25%
M
39%
45%
S
72%
M
32%
75%
S
10%
45%
M,S
39%
71%
M,S
36%
50%
M
75%
10%
33.0%
38.0%
36.5%
37.1%
94%
23%
50.0%
52.5%
48.8%
49.5%
All data
All data
All data
M&S together
Mains only
Services only
10 countries,
112 systems
On average, 38%
reduction in Pmax
produced 53%
reduction in bursts
Average reduction in
mains burst frequency of
1.4 times the % reduction
in average pressure
Source: Thornton & Lambert
Water 21, Dec 2006
Benefits of Pressure Management
Source: Water Services Association of Australia Asset Management Study PPS-3 2011, with later addition of ‘reduced and more efficient use of energy’
Framework for targeting Leakage and Pressure Management
The proven benefits of pressure management in distribution
systems go beyond basic control of leak flow rates, as
initially researched
In fact pressure management is now recognized as the
foundation for optimal management of water supply
and distribution systems
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Basic, Intermediate and Advanced
Pressure Management
There are many ways in which pressure in water transmission and distribution can
be managed. The following is a proposed IWA WLSG broad classification:
 Basic:
o Identify and reduce pressure transients and surges.
o Achieve continuous supply (24/7 policy), even if at low pressure.
o Strategic separation of transmission mains from distribution systems and
zones.
o Monitor pressures (inlet, critical, average), flows, bursts/leaks/repairs,
complaints.
o Avoid overflows from service reservoirs; reduce outlet pressures whenever
possible.
 Intermediate:
o Create sub-sectors (Pressure Managed Areas or Zones).
o Reduce pressure using fixed outlet PRVs or intelligent pumping.
 Advanced:
o Introduce time and/or flow modulation, or feedback loop from a critical node,
or remote control, for valves and pumps.
o Introduce hydraulic flow modulation for valves.
Source: EU Good Practices on Leakage Management Document
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Asset – Pressure Management
Overview Approach
The overview shown in the following slides is not intended to
be a rigid or detailed analysis of pipe failures
Rather, it is suggested as a very general overview of how
changes in pipe failure rates may be influenced by
combinations of:
 operating pressure, surges, age, corrosion
 local influences such as traffic loading
 seasonal influences (ground movement, temperature)
It also suggests why pressure management, to reduce surges
and excess pressure, can show a wide range of % reductions
in burst frequency
New Pipes – No Surges
When new mains and services are laid,
they are designed to withstand existing system pressures
with a large factor of safety, so failure rate is low
NEW PIPES
FAILURE
RATE
PRESSURE
New Pipes, System with Surges
If the new pipe system experiences surges (pressure
transients), the Factor of Safety will be reduced, but the
failure rate should remain quite low.
FAILURE
RATE
NEW PIPES,
SYSTEM WITH SURGES
PRESSURE
Combination of Factors cause
Increase in Failure Rates
As the pipes deteriorate through age (and possibly corrosion), and
other local and seasonal influences, the Factor of Safety is significantly
reduced and the pressure at which failure occurs gradually reduces
until at some point in time, burst frequency starts to increase substantially
COMBINATION OF FACTORS
FAILURE
RATE
CAUSE INCREASE IN
FAILURE RATES
PRESSURE
Pressure Management –
Step 1: Reduce Surges
The first step in pressure management is to check for the presence
of surges; if they exist, reduce the range and frequency of surges
STEP 1: REDUCE SURGES
FAILURE
RATE
PRESSURE
Pressure Management –
Step 2: Reduce Excess Pressure
Next, identify if the pressures at the critical point are higher than
necessary; if so, reduce the excess by pressure management, to
avoid operating the system at higher than necessary pressures
STEP 2: REDUCE
EXCESS PRESSURE
FAILURE
RATE
PRESSURE
Pressure Management –
A Key Element of Effective Leakage Control
Source: A. Lambert and M. Fantozzi
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Important Remarks!!
Pressure Management has the following Benefits:

Water conservation

Reduced pipe failures

Extended asset life

Cost savings
Pressure : Consumption
Thank you
Multumesc!
Bambos Charalambous
J2C Water Ltd
Tel.: +357 99 612 109
Email: bcharalambous@cytanet.com.cy
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