Quick answer
Rusty water is internal corrosion, and which taps produce it tells you where from. Hot water only means the geyser cylinder is corroding internally. Both hot and cold means the galvanised supply pipework. Brief discolouration on both that clears after a couple of minutes usually means the municipality has been flushing or repairing a main nearby, and it will settle on its own.
Common causes
- Galvanised supply pipe corroding internally and shedding rust
- Geyser cylinder corroding, which shows on the hot side only
- Municipal main flushing or repair work stirring up sediment
- Sacrificial anode in the geyser fully consumed, leaving the cylinder unprotected
- Rusty water sitting in the line after a period of no use
- Corroded galvanised fitting on an otherwise copper installation
What you can do now
- 1Run the cold tap for two minutes — if it clears, it is almost certainly municipal work
- 2Test hot and cold separately at several taps and note which produce it
- 3Check whether it is worst on the first draw of the morning, which indicates water standing in corroded pipe
- 4Note the geyser's age; hot-side rust on a cylinder over eight years old is significant
- 5Avoid washing light-coloured laundry until it clears
When to call a professional
If it is hot water only, book a geyser inspection — internal corrosion means the anode is spent and the cylinder is next. If both hot and cold are persistently rusty after flushing, the supply pipework is at end of life and re-piping needs planning rather than reacting. Call promptly either way: rust in the water means metal is being lost from somewhere that holds pressure.
Typical cost in Johannesburg
Pipe re-run R1,400+
Indicative ranges only. We provide written, itemised quotes before any work.
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