WSDP: MODULE 2
TOPIC 9: WATER RESOURCES
9. WATER RESOURCES
Cape Town has seasonal winter rainfall runoff and therefore relies on dam and reservoir
water storage to provide water throughout the year and cover peak demand in a normally dry
summer.
Table 1: Water resource breakdown
Resource
Proportion
Surface Water
98.5 %
Ground water
1.5%
Growth in demand /annum
100%
2006/7
2007/8
2008/9
2009/10
2010/11
2011/12
4.75%
2.29%
3.21%
1.68%
1.69%
-1.8%
The table above indicates that the key resource by is surface water and that there has been
a substantial reduction in the demand growth through a number of interventions. The
reliance on these two sources has kept the cost of water relatively low.
9.1. Surface Water Sources and Volumes
Table 2: Surface water sources (DWA and CCT owned)
Source / Storage Facility
Volume in Mil m³/annum
% of Total
DWA Owned schemes
Theewaterskloof
118
29.6%
Voelvlei
70.4
17.7%
Palmiet
22.5
5.6%
81
20.3%
291.9
73.2%
Wemmershoek
54
13.5%
Steenbras
40
10.0%
Lewis Gay and Kleinplaas Dams
1.8
0.5%
Land en Zeezicht Dam
1
0.3%
Table Mountain Dams
3.5
0.9%
Albion Springs
1.5
0.4%
5
1.3%
Subtotal CCT Schemes
106.8
26.8%
Total Allocation
398.7
100%
Berg Rivier
Subtotal DWA Schemes
CCT Owned Schemes
Atlantis Groundwater Scheme
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9.1.1 Future Water Sources
The CoCT is currently implementing a number of demand management projects with the
effect that the projected time for requirement of new sources of water being moved from
2019 to 2024. Due to ageing water network the unaccounted for water for the city offers an
opportunity for a considerable improvement in water saving. The improved metering of every
zone will allow targeted interventions to reduce loses
Ground water is a small proportion of CoCT water and does not offer major explanation into
the future as a source. The risk as the result of climate change may make the recharge rate
of ground water more erratic and will need extra measure in place to monitor the resource.
Reclamation offers is a huge potential that has not been implemented (for cost and cultural
reasons) however effluent reuse for irrigation has been taken up with little cultural
resistance.
The timing of the development of the required bulk water infrastructure is dependent on the
growth in water demand and the effectiveness of the Water Demand Management (WDM)
Strategy.
To ensure security of supply, the City of Cape Town, in consultation with the Department of
Water Affairs (DWA), is exploring the next water resource scheme to be developed by 2019.
The most probable scheme in the order of economic priority is the raising of Voelvlei dam
(DWA), wastewater reclamation, groundwater (TMG Aquifer) and desalination.
The desalination study is currently underway, the water reclamation study will commence
soon and the pilot for the groundwater (TMG) extraction will also be commencing soon. In
addition, the City of Cape Town will increase the treatment and conveyance capacity of the
bulk water supply to enable optimum utilization of the existing water resource capacity
created by the construction of the Berg River Dam.
To this end, the Bulk Water Augmentation Scheme (BWAS), which entails the construction
of Muldersvlei Treatment Plant (500 Ml/day), reservoirs (600Ml) and conveyance bulk
pipelines (56km), is under planning and design.
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9.1.2 Water returned to resources
Wesfleur Treatment Works at Atlantis is the only WWTW which returns effluent to the source
from which it was extracted (groundwater). All other treatment works have exemptions (in
terms of the 1956 Water Act) from this requirement.
The conditions for greater volumes of return to source will require consideration. There may
be an amendment required to the Act.
9.2 Monitoring
9.2.1 Abstraction of Water Monitoring: Surface Water
Abstraction is monitored with the use of bulk meters which read monthly. This is useful to
calculate water balance. Some of these are read remotely, the CoCT is exploring ways of
doing remote reading on a much larger scale which could dramatically help in improving
water balance calculations.
9.2.2 Abstraction of Water Monitoring: Ground Water
Although less than 2 % of water used in the CoCT is from ground water. It is a valuable
source and is also metered and quality tested by the CoCT.
9.2.3 Abstraction of Water Monitoring: From External Water
As 73.2 % of water is obtained from DWA owned schemes these are quality checked by the
CoCT.
9.2.4 Abstraction of Water Monitoring: Provided to External Customers
As per service level agreements all water provided to external customers monitored
by the CoCT.
9.2.5 Water Levels
All CoCT Dam and reservoir levels are monitored. DWA dam levels and other storage
facilities are also monitored.
9.2.6 Water Quality
The CoCT has achieved blue drop quality status and has established an excellent record of
water quality testing by its scientific services department. There have been recent
complaints about taste and water colour which has been attributed to filters at water
treatment. Monitoring measures have to be put into place to limit these occurrences.
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9.2.7 Boreholes Yields
Bulk potable water is being used for Atlantis and is carefully monitored to prevent over
extraction and to balance the recharge rate. As the cost of water increases and the improved
awareness of water scarcity there are an increasing number of privately owned bore holes
being used for agriculture and garden irrigation. This is use of ground water irrigation is
extensively done in the Philippi agricultural area. There is a need to monitor the impact of
increased levels of ground water extraction particular on environmentally sensitive areas.
9.2.8 Borehole Extraction
Extraction is currently confined to less than 2% of potable water supply. Possible future
sources are:

TMG Aquifer

Cape Flats Aquifer

Newlands Aquifer

West Coast Aquifer Recharge (Langebaan)
9.2.9 Compliance to Drinking Water Acceptable limits
Microbiological and chemical compliance to SANS 241/2005 of the drinking water is
expected to remain in the “Excellent” category.
Growth in the city will require increased monitoring in the newly developed areas. As there is
an ageing reticulation system in large parts of the metro, replacement and refurbishment of
the network requires a large budget. As the rate of pipe bursts increases there would be an
increased chance of contamination. The water main replacement and refurbishment is
considered as one of the CoCT most strategic projects averaging a budget R 40 million/year.
9.2.10 Compliance to Effluent Release Acceptable Limits
The CoCT has an excellent record for the treatment and testing effluent released including
green drop status. The CoCT will continue to test the quality of effluent quality. Currently the
CoCT is upgrading Four WWTW in order to provide acceptable levels of treatment for both
release and its expanding effluent reuse programme.
The WWTW being upgraded at the moment are Potdsdam, Bellville, Zandvliet and Athlone.
During the up grading measures have been put in place where possible to divert some of the
load to other WWTW.
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9.2.11 Number of Sampling Points for Drinking Water Sufficient
The CoCT has managed to achieve blue drop status with its current sampling points and will
continue with this as well as add additional points as new infrastructure is installed and new
areas are developed. The new bulk water augmentation scheme will produce 500Ml /day
and will need a substantial number of sampling points.
Scientific Services will continue to check for improvement in the following areas:

Parameters to be monitored

Sampling location and frequency

Sampling needs and equipment

Schedules for sampling

Methods of quality assurance and validation of results

Responsibility and necessary qualifications of staff

Requirements for documentation and the management of records

Requirements for reporting and communication of results
9.2.12 The Number of Monitoring Points for Effluent Release is Sufficient
Sampling and monitoring at WWTW will include inflow, outflow, process flows, Industrial
effluent and sludge. Industrial effluent has been critical as there has been experience of the
poisoning of treatment works resulting is a protracted period of recovery.
9.3 Water Quality
9.3.1 Reporting on Water Quality Taken from Sources: Urban
The CoCT will continue to take regular sampling and report results monthly to DWA. The
CoCT is committed to retaining its blue drop status will report to regularly to the public and
political representatives in a transparent way (refer to Annexure B 9.3.1. Water Safety Plan
and Annexure B 9.3.1. Drinking Water Incident Management Protocol).
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The commitment to transparency requires regularly notification in the media by:

Making water quality monitoring results available in an accessible way

Informing the public of any possible risks being faced

Warn public of any contamination that has occurred the locality affected and
precautions to be taken

Educating the public on upgrades of supply system that are taking place and what is
required in the future to maintain the level service as well as informing the public of
the real cost of producing good quality water.

Consulting public on decision making that could affect public health as well as
changes in legislation or regulations.

Educating the community on the for saving and conservation of water resources
9.3.2 Reporting on the Quality of Water Returned to the Resource: Urban
The CoCT does operational compliance monitoring of effluent at all its WWTW in
accordance to the DWA requirements for green drop certification (Refer to Annexure B 9.3.2
Risk Abatement Plan). The sampling is done by WWTW staff and testing is done by
scientific services. To ensure quality of effluent the following will require regular checking:

State of infrastructure

Correct functioning of mechanical, electrical, instrumentation and regularity of
maintenance
To achieve this it is recommended that regular inspections and audits are done. The CoCT
has started to implement ISO 9000, 2008 which will assist in the effort to regular inspections
and audits across all sections of the Water and Sanitation department.

Whether the plant is operating within the design and prescribed operational
parameters.

Educating the community on the for saving and conservation of water resources
9.3.3 Reporting on the Quality of Water Returned to the Resource: Rural
The CoCT does not have rural cases of applying this approach.
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9.3.4 Are the Water Quality Results available electronically?
The CoCT makes test results available electronically and is committed to loading results on
DWA’s assessment Data base.
9.4 Wet Industries
The COCT encourages industry to pre-treat effluent before discharging into the sewer. The
city is also rolling out treated effluent reuse many industries have taken up the opportunity to
access cheaper sources of water. There some developments that managed to treat effluent
on site and to reuse.
9.5 Raw Water Consumers
The Bulk water branch of the CoCT has allowed raw water draw offs for agricultural
purposes.
9.6 Industries and Permitted Effluent Releases
Monitoring the effluent releases of all industries effectively has been a challenge for the
CoCT. Although there is regular monitoring of large industries, it can sometimes be the
smaller industries that relies toxic effluent that wipes out the capacity at WWTW. Policing
offenders is particularly important.
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