Water tanks are not on the minor building work list, and the Act's definition of a building includes a reservoir. No national rule sets a tank size above which plans are needed, so this is a question for your council.
What matters in practice is the stand. A 5 000 litre tank holds about five tonnes of water. On a raised stand, wind, the foundation and the frame all need designing, and a collapse is dangerous.
Sources
- National Building Regulations and Building Standards Act 103 of 1977 (the dtic copy)
- SANS 10400-A:2010, Regulations A1 and A2 (minor building work)
Checked October 2026. Councils change their tariffs every July, so confirm fees before you pay.