WWF Water Update – Spotlight on Groundwater

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groundwater

24 JANUARY 2018

Cape Town already has 22 000 registered boreholes, and as Day Zero inches increasingly closer, groundwater has come under the spotlight. In this second weekly update, WWF tells us what you need to know about groundwater.

Where do we find groundwater in Cape Town?

Groundwater is water found underground, which serves to feed 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.

Who controls how much groundwater you’re allowed to use?

The use of groundwater is regulated by The City of Cape Town and the national Department of Water and Sanitation. This includes how much groundwater you can take out and what to use it for.  If you want to drill a borehole, first you have to apply to the City and then register your borehole or well point once it is drilled.

What can you use groundwater for?

You may use groundwater for basic garden and household use but you may not or sell it. The City discourages you from using groundwater to water your garden but rather to save it for flushing toilets.

Is it safe to drink groundwater?

It is unsafe to drink untreated groundwater without testing and treating it. In order to know how to make groundwater safe to drink (potable) you will need do a laboratory test for salts, metals, nutrients and bacteria (preferably the full SANS241). This costs about R2000.

How much groundwater can the City access?

The City is planning to abstract 80 million m3 from the Cape Flats aquifer, 30 million m3 from the Atlantis aquifer and 40 million m3 from the TMG aquifer before the end of this year.

Is our groundwater going to run out?

It is possible that if we take OUT more than is going IN over the long term, groundwater can run out, however it would take longer than rivers and dams to feel the effects of drought. But to ensure that there is a fair share of this hidden resource for everyone for a long time, we need to measure how much we use, monitor the water levels and be sparing.

What about the new rules on metering?

On 12 January 2018 DWS introduced new rules which say all private boreholes must be metered and that the amount of groundwater abstracted must be recorded on a weekly basis and submitted to the DWS. A second new rule also states that we must use this resource sparingly.

What are the dangers of using too much groundwater?

If a lot of groundwater is abstracted close to the coast there is a danger of seawater ‘intruding’ into the aquifer – salt water fills the aquifer and this water then can’t be used by homeowners or farmers. In extreme circumstances where lots of groundwater is removed, the aquifer itself can collapse and land subsidence occurs.

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 an SANAS-registered laboratory. As a minimum you need to know the levels of total dissolved solids (TDS), pH, nitrate, iron, E. coli and coliform bacteria. A full drinking water test is the SANS241 test.

For more information:

www.wwf.org.za/getting-to-grips-with-groundwater

bwa.co.za/laypersons-guide

www.wrc.org.za/ (Groundwater: the myths, the truths and the basics)

www.gwd.org.za/books/where-does-groundwater-come

www.wrc.org.za/Knowledge%20Hub%20Documents/Research%20Reports/TT303-07.pdf

anrcatalog.ucanr.edu/pdf/8085.pdf (how to sample a borehole)

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