Quick answer
Vacuum breakers sit on the hot and cold lines above the geyser and are required by SANS 10254. They stop the cylinder siphoning empty if mains pressure drops, which is what protects the element from dry-firing. They contain a perishable rubber diaphragm, so a weep after a few years is wear, not a defect. Replacement is quick and inexpensive, and skipping it risks the far more expensive failure it exists to prevent.
Common causes
- Perished rubber diaphragm at end of life
- Scale build-up preventing the breaker from seating
- Incorrect installation orientation, which must be vertical to work
- Debris in the line after municipal supply work
- Breaker discharging into the ceiling rather than to the outside, so a small weep does real damage
What you can do now
- 1Identify whether the water is coming from the vacuum breaker or the overflow — they are different parts with different fixes
- 2Check the breaker is mounted vertically; on its side it cannot seal
- 3Look at where the discharge goes; anything weeping into the ceiling needs attention sooner
- 4Note how many breakers are fitted — SANS requires them on both hot and cold lines
When to call a professional
Book it within the month, sooner if it discharges into the ceiling rather than outside. A continuous weep wastes heated water and soaks insulation. Ask the plumber to check both breakers and the safety valve while they are up there, since all three are perishable parts of the same age and replacing them together saves a second call-out.
Typical cost in Johannesburg
R450–R750 per vacuum breaker fitted
Indicative ranges only. We provide written, itemised quotes before any work.
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