WSDP: MODULE 2
TOPIC 8: WATER CONSERVATION AND WATER DEMAND MANAGEMENT STRATEGY
8. WATER CONSERVATION AND WATER DEMAND MANAGEMENT STRATEGY
8.1. WCWDM STRATEGY
The aim of the Water Demand Management and Water Conservation Strategy is to describe,
motivate and illustrate the need for a revised, more comprehensive Water Conservation and
Water Demand Management (WC/WDM) policy and strategy for the City of Cape Town. This
strategy was initially implemented from June 2007. Three years have now passed since the
implementation of the strategy. The City of Cape Town has now revised this strategy to
further project it towards 2020/21.
8.1.1. Assessment of Water Savings and Growth Projections
The impact of the WC/WDM strategy on curbing water demand basically depends on two
main elements:
1. The unconstrained growth in water demand (i.e. what the demand would have
been
without any WC/WDM measures).
2. The actual savings realized through the WC/WDM strategy (including abating water
demand growth).
There are a number of demand projections that have been developed over the last few
years. The DWA Western Cape Water Supply System Reconciliation Strategy used a
demand growth rate of 3% to estimate unconstrained demand (i.e. a ‘Do nothing’ scenario)
based on the historical trend for the period between 1991 and 2000 and basing the curve on
the reported potable water demand from 2000. Figure 1 below indicates this curve.
The DWA Reconciliation Strategy has also adopted two future water requirement curves
namely the High Water Requirement Curve with a demand growth of 3.09% per annum and
a Low Water Requirement Curve with a demand growth of 1.43% per annum. Both curves
using the demand of 2006 as starting point.
2.135
Source: Reconciliation Strategy
Figure 1: Water Demand Projections (source: Recon Strategy)
From Figure 1 it can be seen that from 2001 a significant decrease in the actual demand
occurred and this was more or less maintained up to 2006/7.
The WC/WDM strategy assessed the impact of the implementation of the Strategy on the
need for a new dam and found that the full implementation of the WC/WDM strategy will
result in a new dam only being required by (a review to the Reconciliation Strategy will be
done end of 2012 and figures below are subject to change):

2051 if water demand followed the Low Water Requirement curve

2026 if water demand followed the High Water Requirement curve
2.136
However, it is important to note that this impact assessment was based on the assumption
that there will be no growth in demand after the start of the strategy implementation in 2006
for:

the first 27 years in the case of the LWR (i.e. from 2006 to 2033)

the first 13 years in the case of the HWR (i.e. from 2006 to 2019)
This assumption was based on the anticipation that the full implementation of the WDM
strategy will abate the natural demand growth to 0%. It is important to understand that these
assumptions were made, to the best knowledge available at that stage and that the CCT
worked closely with DWA in the development of the strategy. These assumptions can be
adjusted and the impact of the Strategy re-evaluated as a result of this monitoring and
evaluation process.
The actual average annual demand growth over the period 2006 to 2010 since the inception
of the Strategy is 2.20 % p.a. Table 1 summarises the bulk water treated since 2007/8 and
the demand growth calculations. Figure 1 portrays this graphically.
Table 1: Annual Water Demand Growth
Year
Percentage Water Demand Growth
07/08
2.29%
08/09
3.21%
09/10
1.65%
10/11
1.66%
Average
2.20%
Bulk Water treated a volume equal to 336.64 Mm3/a during 2010/2011
One of the aims of WC/WDM is to postpone the need for further water resource
augmentation scheme.
2.137
Water Demand million m3 per annum
Water Demand Chart
600
500
400
300
200
100
0
1999 2001 2002 2004 2005 2006 2008 2009 2010 2012 2013 2014 2016 2017 2019 2020 2021 2023 2024
Projected Unrestricted
Existing Demand Growth
System yield
Figure 2: Annual Water Demand Growth
Figure 3: Total projected WDM initiative curves (Aurecon)
Source: Bulk Water;
The achievement of the Strategy’s goals should be considered in the light of the discussion
in the previous section on demand projection and demand growth.
2.138
Table 2: Summary of Strategic Goals
Goal
Target
A
Water Losses < 15% by 2015/16
D

Apparent Losses (Unbilled
Unauthorised Consumption)

Real Losses
NRW < 20%

Bad debts

Unbilled Authorised Consumption

Apparent Losses (Unbilled Unauthorised
Consumption)

Real Losses
Quantitative
Quantitative
E
Demand Growth < 2 %
Quantitative
B
On-going effective management systems and
implementation of IWRP
Qualitative
C
Mobilise resources according to the Water
Conservation and Water Demand Management
Strategy.
Qualitative
Source: WCWDM Strategy 2011
In the 2010/11 financial year, a number of successful WC/WDM projects were implemented
of which notable projects were:

Pressure Management was successfully implemented in Crossroads/Plumstead
/Retreat/Marina Da Gama/Lavender Hill. The savings are estimated at2.28 Ml/day;

20 574 dysfunctional consumer water meters were replaced;

95 users were supplied with Treated Effluent which accounts for 30 Ml/day of re-use
(Potable Water replacement of 12.66Ml/day);


60 Schools were visited and leaks repaired ;
o
± 100 Caretakers of schools were trained ;
o
Awareness and Education with approximately 2 688 workshops;
Approximately 200 households were visited for the Integrated Leaks Repair project.
2.139
It must be noted that the actual savings are only shown for those WC/WDM initiatives of
which could be measured, and that the additional immeasurable savings may also have
been achieved.
8.1.2. Reduction of Wastage
The overall target of this goal is to reduce water wastage by consumers. A number of
projects have been implemented involving promotional projects (awareness and educational
campaigns); regulation and enforcement; development and implementation of equitable tariff
structures; customer assistance towards efficient water usage (retro-fit programmes) and
targeting inefficient use within CCT operations.
8.1.3. Water resource management interventions: Situation Assessment and
Implementation progress to date
The annually average water produced in 2010/11 stood at 336.64 Mm3/y. On average, the
volume of water produced has always been greater than water supplied.
Nevertheless, water production steadily increased from 331.1 Mm3 per year in 2009/10 to
336.64 Mm3 per year in 2010/11. The average yearly volumes of water produced in 2010/11
increased by 0.04%.
The Water Demand Management Unit has initiated many projects with the intention of
reducing the water demand. In addition, most of the maintenance activities of the
Reticulation branch also have a Water Conservation/Water Demand Management impact,
for example replacing a leaking water main.
8.1.4. Targets for reducing unaccounted for water and water inefficiencies
Unaccounted-for water (UAW or water losses) for the period July 2010 to June 2011 stood at
18.5%. The target for 10 year Water Conservation and Water Demand Management
Strategy is less than or equal to 15% by 2015/16 according to director objective (see Table
2).
2.140
8.1.5. Reducing high-pressures for residential consumers: urban
Pressure reduction (Installation of smart pressure reducing valves as well as advanced
pressure management). Reducing pressure in the network has an immediate effect on the
leakage in the system and also aids in enhancing the life of the pipe-work infrastructure. It
has the added benefit of reducing the amount of apparent losses that occur as a result of
meter inaccuracies. The latter is due to a smaller volume of water flowing through the meter.
Overall pressure reduction reduces the overall strain and stresses on the overall system.
8.1.6. Reducing high pressures for residential consumers: rural
The City has a very small rural component and reducing pressures here will result in an
insignificant water saving.
8.1.7. Public information and education programmes
Consumers have been made aware of the need to save water through a variety of means.
Many shopping malls have been targeted in the Metro together with the Airwave media.
Display stands have been set up at most events held around the City including during Local
Government-, Water- and Sanitation Weeks.
8.1.8. Leaks Projects
The focus here was to fix leaks in domestic plumbing on private property. The following
projects have been undertaken to date:

Fixing of leaking infrastructure (taps, toilets, cisterns) on low-income household
properties

Installation of Water Management Devices to assist consumers to manage their water
consumptions
8.1.9. Leak and meter repair programme: rural
See urban.
2.141
8.1.10. Working for water programme; Removal of Alien Vegetation
The CCT has an ongoing programme for the removal of alien vegetation in the catchment
areas of their dams. This programme will have the effect of increasing available run-off.
The CCT also contributes towards the removal of alien vegetation in DWA catchments
through a catchment management charge.
The City’s Integrated Aquatic Weed Control Programme aims to assist with management of
alien aquatic weeds which occur in rivers, canals, wetlands, dams and treatment ponds.
Depending on conditions prevailing in the target water body, mechanical, manual, chemical
or biocontrol methods may be recommended.
8.1.11. Treated Effluent Re-use
Two thirds of the City’s water consumption ends up in the 24 Wastewater Treatment Works
and from there the final effluent is discharged back into the environment. The opportunity for
re-using the treated effluent has not yet been fully exploited. Thus far, the majority of Golf
Courses in the City are using treated effluent for irrigation purposes, as do parks and sport
fields. A limited number of Industries are also benefiting from the lower tariff.
Currently, approximately 12 823.16 Ml/month (November 2011, USPC Report) of treated
effluent is used. It is important to note that the volume of treated effluent use does not
directly translate into water demand savings, as not the full volume of treated effluent use
replaces potable water demand. A portion of the use replaces ground water use or in
specific cases what otherwise would be no use at all.
2.142
8.1.12. Water resource management interventions: Future trends and goals
The WCWDM strategy is looking to further implement various programmes/interventions in
order to conserve our water resource and reduce the consumer water demand.
8.1.13. Targets for reducing unaccounted for water and water inefficiencies:
Urban
Table 3: Goal A and D breakdown into sub goal targets
Description
GOAL A
Water Losses

Apparent Losses
(Unbilled
Unauthorised
Consumption)

Unauthorised
Consumption


Customer Meter
Inaccuracies
Real Losses

Leakage on
Transmission and
Distribution Mains

GOAL D
Leakage on
Overflows at
Storage Tanks

Leakage on Service
Connections up to
point of customer
meter
NRW (includes bad debts)

Unbilled Authorised
Consumption

Apparent Losses
(Unbilled
Unauthorised
Consumption)
Real Losses

Actual
Percentage
18.5%
Target
Intervention
>15%
7%
4%
- Meter replacement program
- Meter Audits and data cleanup
1.0%
1%
6.0%
3%-4%
Conforms to International
benchmarks. Water Audits would
be useful in reducing and
maintaining
- Water Audits
- Meter age analysis/Audits
Meter replacement Program
11.5%
11.49%
7%-8%
7%-8%
0.05%
-
0
-
23.2%
>20%
4.7%
2%-3%
7%
3- 4%
As stated in Goal A
11.49%
8-10%
As stated in Goal A
- Pressure Management
- Leak Detection
- Pipe Replacement
Monitor and respond to concerns
– pro-active maintenance and on
demand maintenance/repairs.
-
Metering and monitoring and
pro-active maintenance
As the implementation of the WC/DM Strategy intensifies the assumptions will be tested and
the targets reviewed either up or down depending on the accuracy of the current
assumptions. District management areas will be implemented throughout the Council by
installing additional district meters. Leak detection activities will be intensified and a
dedicated team will soon be established.
2.143
8.1.14. Public information and education programmes
The following programmes/projects will be continued:

Aftercare Programmes & liaison

Schools training
8.1.15. Leak and meter repair programmes: urban
The following initiatives are planned for over the next two years:

Further comprehensive demand projects will be identified and rolled out over the next 5
years. In Delft, the integrated leak repair project was implemented and is now complete.

The Fix-It leak projects will continue in various areas. The Fix-It leak projects targets
high-volume consumers in low cost areas until such a time as a comprehensive demand
project is implemented.

A comprehensive debt management policy has been implemented. Part of the debt
management will be to introduce flow limiters (water demand management devices).
The debt management policy will be implemented as part of the comprehensive demand
management projects but also on an ad-hock basis for high-volume consumers in low
cost areas as part of the Fix-It leak initiative.
8.1.16. Leak and meter repair programmes: rural
Refer to 8.1.15
8.1.17. Funding
There are a number of examples in S.A. where large industries have sponsored various
WC/WDM initiatives by Councils in order to ensure a more secure supply of water. This idea
can be expanded considerably and can be utilised to fund a number of the proposed
WC/WDM initiatives. There are also a number of foreign programmes that offer funding
opportunities. Some examples are the UN habitat programme and the African Cities Water
Conservation programme.
There are a number of private companies that are willing to enter into concessions or joint
management contracts to manage Water Services delivery or specific key performance
indicators such as the reduction of non-revenue demand.
2.144
8.2. WATER BALANCE
By undertaking a water balance, WSAs can calculate the amount of water that is being lost
to their systems. The non-revenue water provides an indicator of how efficiently the water
supply system is being run, and provides information to the WSA on how to improve the
system. Non-revenue water is a direct loss to the WSA.
Table 4: Non-Revenue Water balance according IWA balance
Billed
Authorised
Consumption
707.46Ml/d
Billed metered
consumption
707.46Ml/d
Revenue Water
707.46Ml/d
Billed unmetered
consumption
0 Ml/d
Authorised
Consumption
750.94 Ml/d
Unbilled
Authorised
Consumption
43.48Ml/d
System
Volume
Input
921.29 Ml/d
Apparent
Losses
64.87 Ml/d
Water Losses
170.35Ml/d
Real Losses
105.48 Ml/d
Unbilled Metered
Consumption
29.67Ml/day
Unbilled Unmetered
Consumption
13.81 Ml/d
Unauthorised
Consumption
9.59 Ml/d
Customer Meter
Inaccuracies
55.28 Ml/d
Leakage on
Transmission and
Distribution Mains
105.99 Ml/day
Leakage on
Overflows at
Storage Tanks
0.45 Ml/day
Non-Revenue Water
213.83 Ml/d
Leakage on Service
Connections up to
point of customer
meter
Negligible
Note: The calculation of the IWA water balance was performed using the best available
information at present and in some cases estimation based on input from officials within
Water and Sanitation. Therefore the accuracy of the IWA water balance can still be
improved.
2.145
Table 5: NRW Trends
Year
Overall NRW
NRW LOSSES (Ml/day)
BULK TREATED (Ml/day)
2006/7
19.36%
165.62
845
2007/8
20.22%
174.90
865
2008/9
23.30%
207.84
892
2009/10
25.37%
230.11
907
2010/11
23.20%
213.83
921
The non-revenue water has decreased from 25.37% in 2009/10 to 23.20% in 2010/11.
Note: Expressing NRW as a percentage of the system input is not encouraged as it can be
misleading as percentage figures are strongly influenced by the consumption.
Previous trends, before 2010/11, showed steady increase in the overall NRW. One of the
objectives of the strategy was to have a system in place which assesses the overall water
balance.
Possible reasons for improved NRW value:

Meters replaced/ New connections

WDM Device installation (debts written off – indigent households)

Pressure Management
There is a need to develop or set a system which will aid in accurately determining and
analyses of water losses as per requirements as set out by IWA
2.146
8.4. TREATED EFFLUENT RE-USE
The table below lists the measured volumes of treated effluent consumption for the month of November 2011 being used instead of potable water.
12 month history
Current Month
NO PLANT
1
Cape Flats
WWTW
2
% OF TE
CAPACITY
CAPACITY USED
RE-USED
Oct-11
Sept-11
Aug-11
July-11
Jun-11
May-11
Apr-11
Mar-11
Feb-11
TE CAPACITY % OF
(Ml/month)
PLANT
188.32 172.52 111.9 98.0 334.9 187.1 113.8 113 252.7 116.6 189.4
284.4
6 000
483
4.7
58.9
Potsdam
WWTW
499.30 565.44 899.59 826.9 851.6 789.1 400.9 353 330.8 423.1 386.9 682.7
715.4
1 410
1 398
50.7
51.2
3
Melkbosstran
d WWTW
2.37
3.00
0.00
14
16.1 35.9 24.3 56.8
57.0
162
66
35.2
86.4
4
Parow
WWTW
Macassar
WWTW
Kraaifontein
WWTW
Scottsdene
WWTW
Bellville
WWTW
18.48
27.24
22.92
1
0.3
23.1
21.9
36
57
60.8
38.4
30.64
71.40 104.14 44.2
50.9 99.3 80.0 55.3 31.4 48.5 46.8 37.8
51.5
1 710
333
3.0
15.5
5.174
42.62
19.55
6.6
43.7 50.8
8.9
9
21.514
10.32
14.50
14.4
11.6 13.3
1.8
1.9
56.969
86.93
34.35
Atlantis
WWTW
0
33.61
10 Athlone
WWTW
1
0.00
5
6
7
8
9
132.50
Jan-11
Dec-10
Nov-10
CONSUMPTION PLANT
(Ml/month)
CAPACITY
(Ml/month)
101.5 49.6 58.6 20.5
9.3
5.7
4.9
3.1
3.5
4.2
13.4 15.6
7.3
13.9
29.5
525
270
5.6
10.9
1.4
0.6
7.5
0.6
360
249
0.2
0.2
7
13.8 78.6 43.5 47.8 36.6 66.5 58.5 32.5
46.0
1 650
585
2.8
7.9
35.61
32.9
32.5 27.7 26.7 29.4 19.8 36.4 67.3 53.7
25.2
420
192
6.0
13.1
52.24
64.8 109.6 73.4 17.8 11.6 12.9 16.4 21.1 57.3
63.2
3 150
459
2
13.8
2.5
COMMENT ON EVENTS
OR WORK
UNDERTAKEN AT EACH
EFFLUENT SUPPLY
POINT
11 Mitchell’s
0
0.5
1 350
183
0
0.3
An upgrade for this plant is
0.26
0.00
0.00
0.1 1.2 0.1
0
0
0.8 1.4 2.7
Plain WWTW
currently in the EIA stage.
12 Gordon’s Bay
0.098
0.2
0
0
0
93
60
0
0
This plant is not providing
0.01
0.37
0.1 0.2 0.1
0
0
0
WWTW
effluent.
TOTAL VOLUME 768.315 1 028
1 356 1 220 1 267 1 532 790.5 636.8 575.7 901.9 735 1157.
1295.2
16 866
4 335
7.7
29.6
OF TREATED
4
EFFLUENT
(Ml/month)
NOTE:The consumption figures for November increased considerably from October with more effluent being used for irrigation. November’s usage compares favourably with the months usage in
2010 showing an increase of 641.6Ml. We are endeavouring to bring more end users online by expanding our treated effluent networks, it can be seen in the TE Capacity (Ml / month) column that
there is much potential for more effluent usage.
2.147