Cape Town still has water, Jim, but not as we know it.

Again personal opinion:

We should note that we are in a hydrological drought brought on by below average rainfall, which severely impacts CoCT because it relies 98% from surface water (dams) to supply drinking water.

So although we are in a hydrological drought, Cape Town still has water, Jim, but not as we know it.

Use less water. South Africa is water scarce as level 2 water restrictions should be the commonly accepted practice by all of us. A daily consumption of 250 l/day still puts South Africa as one of the largest water users (http://aspirenews.org/621/blue-zone/water/water-by-the-numbers/) despite our low rainfall. Using less water also makes more water available at zero capital costs which is perfect!

Fix the leaking pipes. Non-Revenue water in SA stands at around 36.8% so continue to replace and fix those leaking pipes! (http://www.wrc.org.za/Knowledge%20Hub%20Documents/Research%20Reports/TT%20522-12.pdf) Also note that the greater the distance to bring water to where it is needed, the greater the network of pipes which need to be fixed and monitored for leakage.

Stop flushing toilets with drinking water from the Boland.  Crazy I know right? Perhaps all houses (especially new houses) should be designed to use grey water or rainwater to flush toilets and not drinking water. Flush toilets have been around for decades. Many improvements to the design have been done but these are not implement in large scale production – why? – because there isn’t the consumer need. Let’s start buying and demanding more water efficient toilets so they can start producing them full scale. Just note that currently our waste water treatment works rely on the dilution when flushing to treat effluent. Any large change would need to be done with an upgrade to the waste water treatment loads to insure they can handle the increased nutrient loads.

Decentralised water supply. Why rely on government for water? Why not capture your rainwater in winter and store it until summer to irrigate your garden. Why not use greywater (just make sure you aren’t polluting the groundwater resource)? Why not get a wellpoint or a borehole (Just note that groundwater and surface water are connected – one resource. So don’t waste groundwater).

What Does Cape Town have planned:

CoCT has planned the following: The first additional scheme is Voelvlei Augmentation Scheme which will come on around 2021 when additional water will be pumped from the berg River into Voelvlei Dam.

A City project is the reuse project – to be in place by 2023 – 100 mega litres of waste water recycled to drinking standard in the first phase.

The third, phased project is the Table Mountain Aquifer Group project for 2024,  (http://www.capetalk.co.za/articles/239593/billions-of-cubic-metres-of-water-in-table-mountain-group-aquifer)

What about water security?

So how do you increase water security in a changing climate? We need alternate water resources, so if one fails or is under pressure like surface water during a drought, we increase the usage of the water sources, and then go back to sustainable use afterwards.

No more dams – Cape Town is already 98% reliant on dams, hence the current predicament of our severe drought. Drought frequency and intensity is also expected to increase with climate change. The annual average potential evaporation for Cape Town is between 1400mm and 2200mm. So for a standing body of water, between 1.4m and 2.2m evaporates every year (this applies to swimming pools which don’t have a cover on it too)

Desalination – Things to consider: Where does the water come from, where does the energy come from, where does the water go, where does the waste go, cost.

Costs continue to decrease (but it is still expensive). Desalinating sea water is costlier than saline water and produces more brine. South Africa is still in an energy crisis so should we be diverting our precious energy to produce drinking water if there are alternate and cheaper water? Desalination should not be done using coal fired energy from Mpumalanga because this moves the high water footprint to another part of the country and doesn’t solve the problem. Water is used to mine coal, wash coal and used by the coal fired power stations as a coolant. In addition water is polluted by coal-based activities in the form of acid mine water and acid rain. There are also massive transmission loses as the electricity is transported across the country in the power lines. Koeberg and Nuclear Power is an option. Koeberg is by the ocean and generates electricity that can be used without transmission loses. The issue would be transporting the water from Koeberg to Cape Town. The pipeline between Atlantis and Cape Town only runs in one direction (from Cape Town), despite Atlantis having an abundant groundwater resources and artificial recharge scheme. But should we invest in desalination from nuclear power when the future of nuclear is so uncertain in South Africa, and fraught with allegations of corruption.  So desalination costs a lot in terms of capital expenditure and maintenance and should we be investing money in it when there are cheaper water resources?

Rainwater Harvesting. Rainwater harvesting is a decentralised or individual option. It is easy to capture winter rainwater in jojo tanks, and then store it until it is needed. Rainwater harvesting can become a municipal requirement for all new developments. There are issues with the long storage time and the growth of bacteria, especially during the host summer months, so would not recommend using rainwater for drinking water. Just note that the rivers require rainwater to dilute the urban pollutants so if all rainwater was captured our rivers would become heavily polluted.

Stormwater. Currently our stormwater is flowing out to sea and could be captured and used. This water would have a high cost of treatment as our cities are dirty. UCT is looking at future city options like permeable pavements to filter and treat the stormwater before it enters the drain. Just note that the rivers require stormwater to dilute the urban pollutants so if all storm water was captured our rivers would become heavily polluted.

Recycling water. Recycling water is a very good option. No transport of the water is needed as it is already in the urban system. The problem is the public is against drinking recycled water and does not trust that it is clean and safe to drink. Whilst there are complicated pharmaceuticals and endocrine disruptors in our waste water, these can be monitored and mostly removed if the water is going to be used for drinking water. Treating water back to drinking water quality is costly, but it is cheaper to treat it for the purpose which it can be used, such as irrigation or industrial use….or for flushing toilets (yes I keep on getting back to that).

Groundwater. Groundwater yes it can! Does Cape Town have a lot of groundwater? Yes. There is the Capfe Flats aquifer, Table Mountain Group Aquifer, Newlands Aquifer, Atlantis Aquifer, Camissa Springs, Newlands Spring etc. etc. etc. While surface water is stored in Dams, groundwater is stored in aquifers…which means….no evaporation! Groundwater does not suffer from the massive evaporation loses like surface water dams…also the rock or sand (which makes up the aquifer) generally provides a filtration function and purifies the water. Are we drinking groundwater already? Yes! Most of bottled water is spring water which is…groundwater. SAB Newlands brewery uses pristine spring water from the Newlands/Albion Spring in its beer. Table Mountain Ground Aquifer is also excellent quality water. But, like surface water, not all groundwater is of drinkable quality and some require treatment. The Cape Flats aquifer, thanks to apartheid land planning practices, has had its quality heavily impacted. So with the Cape Flats aquifer, we have the water but it would need treatment in order to be used. Consequently, one of the reasons that Cape Town always has floods in winter in the informal areas is because the groundwater in the Cape Flats aquifer is not being used. Instead the water table is sitting close to the surface so by the end of the winter rainfall, the rain cannot seep into the ground and instead floods of the surface – so although it might be costly to treat the Cape Flats aquifer, by dewatering it we mitigate our winter floods in the informal settlements on the Cape Flats as well as the health impacts of the annual flooding.

So why isn’t groundwater being used more?

  • People, politicians and engineers love dams. They’re charismatic and people can see that government is doing something about it. Which headline would make you feel good “Government spends billions building a new dam” or “Government spends millions drilling a few boreholes”
  • Groundwater is underground so it cannot be seen, unlike a dam which is easy to see and monitor. Groundwater can be monitored and utilised, especially by groundwater specialists.
  • People know dams but don’t know groundwater (despite drinking a lot of it).
  • Groundwater is much cheaper to develop in terms of capital investiture compared to building a dam, but still the public perception (which influences the political decisions) is that dams are the answer.
  • We have the expertise for groundwater in Cape Town (University of the Western Cape) but civil engineers have the partnership with the construction firms, and we all remember the collusion with the “construction cartels” for the World Cup in the building of SA’s soccer stadium. That’s quite a machine to go up against….

 

So, what are you doing to make yourself water secure?

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Photo from Daily Maverick

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One thought on “Cape Town still has water, Jim, but not as we know it.

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