Municipalities are water authorities ito of Water Services Act and under the Constitution, basic infrastructure incl water and sanitation are among their functions and powers. Cape Town was a partner with the Department of Water Affairs and Trans-Caledon Tunnel Authority on the Berg River Dam. So muni's have significant control and responsibility for water.
See https://www.thesouthafrican.com/watch-cape-town-warned/. In 2007 DWA warned the city it would run out of water by 2015 but due to 'overconfidence' - the city said it would only need more water in 2022 - and good rains it made 'bad management decisions'. De Lille, Zille et al keep referring to plans, but there are none. They also keep blaming residents when it's politicians' fault.
I don't like the ANC too but please stop tiresomely being in denial about whose fault it is - the DA-run city. Once we're clear we'll know what to do next election, or sooner if you'll join the campaign to #FireDeLille&Limberg.