Cape's groundwater will gain in importance from Day Zero
Collected rainwater and groundwater are critical “off-mains” sources of water that now are helping households reduce the demand for bulk water, and will be even more important when the taps are turned off.
Groundwater is a hidden resource that is a national asset and belongs to all South Africans. As Cape Town already has 22000 registered boreholes, it’s a privately accessed resource and, by default, under the influence and “management” of thousands of users.
With the City’s new water restrictions pegging personal use to a maximum of 50 litres a day from February 1, groundwater use is increasingly under the spotlight.
1. Where do we find groundwater in Cape Town?
Groundwater is found beneath much of Cape Town and feeds the springs around the city. Cape Town has three major aquifers: the Table Mountain Group (TMG) aquifer found beneath the mountain and high-lying suburbs, the Cape Flats aquifer and the Atlantis aquifer.
2. What’s the difference between a well-point and a borehole?
Well-points tap into loose sand aquifers. They are generally shallow, have a narrow diameter pipe and are quick to install. A borehole can vary from a few metres to hundreds of metres deep.
3. Who controls how much groundwater you’re allowed to use?
The Department of Water and Sanitation (DWS) controls all aspects of water use. This includes how much groundwater you can take out and what to use it for.
And, unless you have been given a licence by DWS, you are not allowed to pump more than 400m³ per hectare per year in Cape Town - which is about 1000 litres a day (that equals to only about 100 litres per day on a 1000m² stand/erf ).
4. What can you use groundwater for?
You are allowed to use groundwater for basic garden and household use but you may not use it on a commercial scale or sell it. Life beyond Day Zero will present exceptional circumstances, and we hope that emergency by-laws will be brought in to enable Capetonians to use and share groundwater with neighbours.
5. Is it safe to drink groundwater?
Under normal circumstances, drinking water should come from treated mains water.
It is not safe to use untreated groundwater to drink without testing it, and in many cases treating it.
6. Where will the City access new sources of groundwater?
The City is planning to abstract 80million m³ from the Cape Flats aquifer, 30million m³ from the Atlantis aquifer and 40million m³ from the TMG aquifer before the end of this year. The TMG well fields are mainly outside the metropolitan area near Grabouw.
7. Is our groundwater also going to run out?
Like any renewable resource, if we take out more than is going in over the long term, groundwater can run out.
Day Zero prep - this week’s Bucket List:
If you have a borehole or well-point:
1. Make sure your pump is in good working order. When was your pump last serviced? Do you have necessary spare parts? Now is the time to think ahead, get it serviced and make sure you can rely on it.
2. If you haven’t done a water quality test within the last six months, test your water quality at a Sanas-registered laboratory.
If you don’t have a borehole but your neighbour does: Start talking to them about sharing emergency access to their groundwater after Day Zero.
For more information: bwa.co.za/laypersons-guide, www.wrc.org.za/, www.gwd.org.za/books/where-does-groundwater-come, www.wrc.org.za/Knowledge%20Hub et al.
WWF is grateful for the participation of the following experts in compiling this Thursday water file: Marlese Nel (UWC), Fanus Fourie (DWS), Roger Parsons (Groundwater Division of the Geological Society of South Africa), John Holmes and Chris Hartnady (Umvoto Africa).
World Wildlife Fund SA