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For most South African homes the geyser is the single biggest electricity user, and it is also the appliance most likely to cause expensive water damage when it fails. It sits quietly in the roof for years, then one day the ceiling is wet. The good news is that geysers usually give notice before they fail, and a little regular attention can add years to their life and trim your electricity bill at the same time.
How your geyser works
A typical home geyser is an insulated steel tank that holds hot water. An electric heating element warms the water, a thermostat switches the element on and off to hold the set temperature, and a number of safety valves protect the tank from too much pressure. Because it involves mains water and mains electricity together, the geyser is a job where plumbing and electrical skills meet, and where mistakes can be dangerous.
Warning signs your geyser needs attention
- Water dripping from the overflow or pressure relief pipe. A small amount during heating can be normal. A steady drip or flow means something is wrong, often a worn valve or too much pressure.
- Rusty or discoloured hot water. This can point to corrosion inside the tank.
- Water takes much longer to heat, or runs out quickly. Often a failed element or thermostat, or a build-up of scale on the element.
- Banging, popping or rumbling noises. Usually scale or sediment at the bottom of the tank.
- Damp patches, stains or sagging in the ceiling below the geyser. Act immediately, as the tank or a connection may be leaking.
- The breaker or earth leakage trips when the geyser heats. A failing element can leak current to earth. Do not keep resetting it. (See why your earth leakage keeps tripping.)
- A tank that is more than about ten years old. Lifespan depends on water quality and maintenance, but older tanks fail more often.
If you see water coming through the ceiling, switch the geyser off at the distribution board, close the water supply to the geyser, and call us.
The safety parts you should know about
Pressure relief (safety) valve
This valve opens if pressure in the tank gets too high and so prevents the tank from rupturing. It should be checked and, if it is worn, replaced. Do not block or cap the outlet pipe.
Vacuum breaker
Prevents the tank from being damaged when the water supply is cut, such as during a burst main or municipal maintenance.
Drip tray and overflow pipe
A geyser in the roof should sit in a drip tray with a correctly sloped overflow pipe that discharges somewhere visible outside. This turns a leak into a visible drip instead of a collapsed ceiling. Many older installations have a blocked or missing tray.
Thermostat and thermal cut-out
The thermostat controls the temperature. The thermal cut-out is a back-up that switches the power off if the water overheats. If your geyser ever behaves as if the thermostat has failed, have it checked at once.
Sacrificial anode
Some tanks have a sacrificial anode that corrodes in place of the tank walls. Replacing it when it is used up can extend the life of the tank. Ask your plumber whether your geyser has one.
Simple maintenance that pays off
- Look at it twice a year. Check the drip tray, the pipework and the ceiling beneath for stains or damp.
- Test the pressure relief valve. Lift the lever briefly, as the manufacturer instructs, and make sure water flows and then stops. If it keeps dripping afterwards, it needs replacing.
- Have the element and thermostat checked if heating times get longer, or every few years in hard-water areas.
- Insulate the tank and the first metre or two of hot and cold pipes. A geyser blanket and pipe lagging reduce standing heat loss.
- Keep the roof space clear and make sure access is safe for a plumber.
Saving electricity
Because the geyser is such a large load, small changes add up:
- Lower the thermostat. Around 60 °C is commonly recommended, hot enough to limit bacterial growth in the tank but not wasteful. Higher temperatures use more power and increase scale and scalding risk.
- Use a geyser timer or smart controller. Heating water only when you need it, for example in the early morning and early evening, avoids reheating a full tank all day.
- Insulate. A good blanket and lagged pipes are one of the cheapest savings available.
- Fix dripping hot taps. A slow drip wastes both water and the energy used to heat it.
- Consider solar or a heat pump. The upfront cost is higher, but running costs can be much lower. Ask us whether your roof and household use suit it.
Load shedding and geysers
Many households now switch their geyser off during outages, and that is sensible, because a geyser starting up the moment power returns adds to the surge on your circuit. A timer helps here too. Do not run a geyser from a small inverter unless the system is properly sized for it, since an element draws a lot of power and can overload an inverter that was not built for the load. Also make sure any inverter or changeover arrangement was installed by a qualified electrician.
Repair or replace?
A failed element, thermostat or valve is usually a straightforward repair. If the tank itself is leaking, repair is generally not possible and the geyser must be replaced. As a rough guide, if the tank is old, rusted or has leaked, or you are repeatedly paying for repairs, replacement is usually the better value. When we replace a geyser we also look at the drip tray, overflow, valves and isolating switch so the new installation is safe and compliant.
If replacement is on the cards, our Geyser Replacement Cost in Johannesburg (2026 Guide) breaks down what to budget.
Insurance and compliance
Many insurers expect a geyser to be installed by a registered plumber, and some require the work to be certified. Keep your invoices and any compliance paperwork. If your geyser bursts, photographs and a written report from a plumber about the cause can help support your claim. Check your policy for conditions and excesses.
Frequently asked questions
Is it normal for my geyser to drip?
A little water from the overflow while the water heats can be normal as it expands. A constant drip or flow is not, and you should have it checked.
Why does my hot water run out so quickly?
Common causes are a failed element, a faulty thermostat, heavy scale build-up, or a tank that is too small for the household.
Can I replace the element myself?
We recommend against it. It involves isolating power and water, working in a roof space, and correctly testing afterwards. A mistake can mean electric shock or flooding.
How long does a geyser last?
Roughly ten years is common, but it depends on the tank, the water and how well it has been looked after.
Let us help
Supa Nova Electrical Power & Plumbing has been serving Johannesburg since 1981. As both electricians and plumbers we can inspect your geyser, valves, drip tray and wiring in one visit, repair or replace as needed, and advise on timers and ways to cut your bill. We cover a 20 km radius of Maryvale, offer free quotations, and charge no call-out fee: just labour plus a R400 travelling fee. We work Monday to Friday, 7:00 to 17:00 (Saturdays by prior arrangement).
Whether your geyser needs a service, a repair or a full geyser replacement, our plumbers can help, and our emergency plumber service is there if it bursts. We can also issue a plumbing certificate of compliance.
Call us on 011 485 1324 to book a geyser check before it checks you.