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    What Is a Geyser Vacuum Breaker — and Why a Faulty One Floods Your Roof

    The small vacuum breakers on your geyser are a common, overlooked failure point. What they do, why they leak onto your roof, and the cheap fix every Joburg homeowner should know.

    1 April 2026 5 min read
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    Of all the parts on a geyser, the humble vacuum breaker causes more mystery "roof leaks" than almost anything — and almost nobody knows what it is. Here's the small component every Johannesburg homeowner should understand.

    What it does

    Your geyser has two vacuum breakers — one on the hot line, one on the cold. They let air into the system to prevent a vacuum forming, which would otherwise siphon the geyser empty and damage it if the water supply drops. They're a required safety component under SANS 10254 — small and cheap, but important.

    The mystery roof leak

    When a vacuum breaker perishes, it leaks — often onto the roof or out an overflow. Homeowners frequently mistake this for a roof leak and chase the wrong problem. In reality, replacing the perished vacuum breaker is a cheap, quick fix that stops the water.

    Why they fail

    They perish over a few years, faster with high water pressure, making them a frequent cause of geyser-area leaks. Replacing them during a geyser service heads off both the leak and the damp damage it can cause.

    Catch it early

    It's an inexpensive part, but ignored it lets water track into ceilings. If you've spotted water near the geyser or on the roof, have the vacuum breakers checked before assuming the worst — see valve replacement or book a geyser check.

    Frequently Asked Questions

    Vacuum breakers (one on the hot line, one on the cold) let air into the geyser system to prevent a vacuum forming, which protects the geyser from being siphoned empty and damaged if the water supply drops. They're a required safety component under SANS 10254 — small, cheap, but important.

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