Greater Efficiency not Desalination to Save Cape Town

Sane answers from Cllr Xanthea Limberg’s professional staff around questions on desalination and what the city is doing to manage the water crisis.

Q: Is desalination part of the solution for a secure supply of potable water for Cape Town and if so why is Cape Town not exploring this?

A: Cape Town is a system with 97% to 98% assurance of supply, it means that in two to three years out of a hundred, there will not be sufficient water to meet the normal demand. The system makes allowance for this by permitting the City to implement restrictions to meet savings targets imposed by National Government. Lowering consumption during a time of drought, or even proactively as the City started doing in advance, is in accordance with international best practice.

2016 06 26 rain dropsTogether with the many people of Cape Town and businesses, we have already managed to reduce consumption by 400 million litres of collective use per day compared with a similar time last year. This is no mean feat and we will continue to target those who have not come to the party. To put this into perspective, in terms of desalination costs one study shows that for the City to build the first phase of a 450 million litre per day desalination plant could cost approximately R8 billion excluding VAT for a yield of 55 million m3 per year (some infrastructure for the ultimate full production would need to be completed as part of the first phase). This would have to be recovered by the tariff and would have significant implications for the cost of water.

Our system is designed and modeled on the fact that the operating rule for drought years is to introduce the necessary levels of restriction to limit the demand in order to ensure sustainable supply – as per international best practice. Therefore, we promptly responded to lower rainfall as early as 2015 by implementing Level 2 water restrictions, which pre-empted a directive from the National Department of Water and Sanitation to do so.  Over a year, we’ve lowered consumption by as much as this study shows the first phase of a desalination plant could produce per year.


Long-term planning and implementation of water supply schemes is done in collaboration with the National Department of Water and Sanitation and according to projected population/demand growth and rainfall projections. Based on these projections, a new supply scheme was not necessary until 2021. 

We have solid plans in place, we have been implementing certain water demand and conservation initiatives since 2000 we have been recognised as an international leader of water demand and conservation efforts. It must be emphasised that the reason dam levels have depleted so much is not because of any sudden increase in demand, or high levels of water lost through leaks and bursts, or any issue that can be influenced by management. It is because we have received abnormally low rainfall for two years in a row.  

A question not asked or answered is whether the modelling takes sufficient account of the lower rainfall predicted by Climate Change.

Because of the scale of water supply infrastructure needed for a large city like Cape Town, on a practical level, new supply schemes must be carefully planned and our supply schemes are all on track to be implemented when our extensive modelling has found to be the appropriate time.

Q: What is the city doing to harvest local water sources such as rain run-off and water from City springs. 

A: The City has just concluded a study regarding how run-off water can be used more extensively in a sustainable manner. The City is now engaging with the Department of Water and Sanitation and other stakeholders and preparing a license application for further use of the water.

Certain high-yielding springs can be used for irrigation of sports fields, parks and other larger-scale gardens. Currently the known use in the CBD is the irrigation at the Cape Town Stadium and surrounding area, cleaning of streets and irrigation in sections of the Company’s Garden. These springs have not been considered to supplement drinking water supply because the expense of enabling the City to treat this water would not justify the small amount of drinking water that this would yield. Filtration and disinfection barriers would be required to protect community health, as would a pressure feed into the adjacent network and additional staff to control the treatment process. Use of the water for other purposes such as irrigation or industrial processes would be more cost-effective and simpler to achieve and off-set unnecessary use of potable water. The yield from these springs is not such that it would offset the effects of the current drought, however the planned usage will take some pressure off the City’s potable water reserves.

Q: Who are the high water users who have not responded to calls for efficiency?

A:  Regarding business and hospitality:  As you may know, the Executive Mayor of Cape Town, Patricia de Lille, as well as the Executive Deputy Mayor, Alderman Ian Neilson, have engaged in a regime of calling businesses, such as hotels, to see what they are doing to save water. In addition, to warn them where we spot high water use.

DIY grey water from shower to garden

DIY grey water from shower to garden

The response has been overwhelmingly positive, with many businesses sending us e-mails of what water-saving measures they have started to implement after these calls, or how they are sitting up and taking notice of their high water use and investigating why it is extreme in some cases.

Informal Settlements and tourists are often popular scapegoats but compared to the formal residential sector, which uses about 65% of all water supplied, they use very little. 

Such speculation is dangerous in that many people could relax their savings efforts or use these kinds of excuses to dodge the responsibility they have to reduce their water usage.

 

Based on our figures 2015/16 water consumption figures and the 2011 census, an average formal household (formal houses, flats or group house) uses slightly more than three times more water than an average informal household.

Unless we all, residents, businesses and government, make significant changes to our water habits, we will face much more hardship down the line. If residents would like to report a contravention, they should please do so by sending an email to water.restrictions@capetown.gov.za. Evidence should be provided to help the City to bring culprits to book.

Thank you for your own efforts to use water sparingly, and also for your concern about the issue.

Cllr Xanthea Limberg, Mayoral Committee Member for Informal Settlements; Water and Waste Services; and Energy.

Posted 27 February 2017

Comment: Using water efficiently must become a way of life for all in the Western Cape.  The other reality is that water is going to cost us more- either from the tap or through investments in water harvesting and grey water systems. Just as we have learnt to become more efficient in our use of electricity to`adapt’ to high electricity costs, so we are going to need to become efficient water users and collectors.  There has also been some talk about reducing the allocation of the 6 kiloliters of Free Basic Water.  This does not appear to be imminent, but appears to be under consideration, nationally as well as locally.  So best to build our water resilience and take the good lessons learnt from this drought into everyday living.

Kim Kruyshaar

One Response to Greater Efficiency not Desalination to Save Cape Town

  1. Junius October 18, 2017 at 12:14 pm #

    i.e. the City’s strategy has been to hope for rain. Plan B is presumably to pray for it.

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