Tankless vs Traditional Geysers: Which Is Right for You?

Tankless (instant) geysers come up a lot in conversations with Midrand and Johannesburg homeowners planning a geyser replacement — usually framed as “should I just switch while I’m replacing it anyway?” The honest answer depends on your household, your existing plumbing, and what you’re actually trying to solve. Here’s a straight comparison.

How a tankless geyser actually works

A traditional geyser heats and stores a tank of water (150L–200L is typical for a home), keeping it hot and ready around the clock. A tankless unit has no storage tank at all — it heats water as it flows through, on demand, the moment a tap or shower is opened. No standing tank means no standing heat loss between uses, and in theory, hot water for as long as it’s running rather than until a tank runs cold.

Where tankless genuinely wins

• No standing heat loss — a traditional geyser reheats stored water continuously to maintain temperature, even overnight when nobody’s using it. A tankless unit only uses energy while water is actually flowing.
• Never runs out mid-shower — there’s no finite tank to deplete, which matters for larger households where someone’s always waiting for “the tank to reheat.”
• Smaller footprint — no bulky tank to fit in a ceiling or cupboard, relevant for smaller Midrand apartments and townhouse units where geyser placement is already tight.
• Load shedding resilience is different, not necessarily better — a tankless electric unit still needs power the instant you turn on a tap, so it offers no hot water during an outage, same as a traditional geyser with a depleted tank. A gas tankless unit sidesteps this entirely, which is why the two are often discussed together.

Where tankless falls short

• Flow rate limits — an electric tankless unit can only heat so much water per minute. Two showers running at once, or a shower plus a dishwasher, can outpace a single unit’s capacity, resulting in lukewarm water rather than a full flow of hot.
• Higher upfront cost — the units themselves, plus the electrical work often needed (tankless electric units typically require a dedicated high-amperage circuit that older Midrand and Johannesburg homes may not already have), usually costs more than a like-for-like traditional geyser swap.
• Retrofit complexity — swapping a traditional geyser for tankless isn’t just a unit swap. It can mean new electrical wiring, sometimes a distribution board upgrade, and re-routing pipework depending on where the old geyser was positioned versus where a tankless unit needs to sit.
• Multiple units for a larger home — a single tankless unit often can’t serve a full house with several bathrooms running simultaneously. The realistic option is sometimes multiple smaller units placed closer to point of use, which adds to the cost.

Electric vs. gas tankless

Electric tankless units are simpler to install where the electrical capacity already exists, but they’re bound by the same grid dependency as any electric geyser — no power, no hot water, load shedding included. Gas tankless units solve that specific problem and tend to have a higher flow-rate ceiling, but they come with their own installation requirements — proper ventilation, correct gas line sizing, and a gas Certificate of Conformity, distinct from the water-side PIRB compliance certificate. If load shedding resilience is the main driver behind considering tankless at all, gas is usually the option that actually delivers it; electric tankless doesn’t.

So which one actually makes sense?

A traditional geyser still make sense for most single-family homes with fairly predictable, sequential hot water use — one shower running at a time, standard household size. Tankless earns its higher upfront cost where the specific pain point is genuinely “we keep running out of hot water” in a household with several bathrooms in near-simultaneous use, or where ceiling/cupboard space for a tank is a real constraint. If the actual goal is load shedding resilience rather than never running out of hot water, that’s a gas conversation (either a gas storage geyser or gas tankless), not necessarily an electric tankless one.

What a proper tankless installation quote should include

An honest assessment of your home’s electrical capacity (or gas supply, for a gas unit) before recommending tankless at all, correct sizing for your household’s actual simultaneous hot water demand, any electrical or gas line work required stated up front rather than discovered mid-installation, and the relevant compliance certificate — PIRB for the water side, a gas Certificate of Conformity if it’s a gas unit. If a quote skips straight to “install a tankless unit” without assessing whether your home can actually support it, that’s worth questioning before committing.