Water heating: the largest saving in most Pakistani homes

Short answer. A 2,000 watt storage geyser left switched on cycles for roughly nine hours a day to hold a tank of water hot that nobody is using — about 540 units a month. Heating it for two hours before bathing instead costs about 120. No other single change in a Pakistani home is worth as much.

Applies: Winter · Cost to do: Costs nothing · Indicative saving: around 400 units a month

Standby loss is the entire problem

A storage geyser holds thirty or so gallons at temperature. Heat leaks through the tank wall continuously, and the element restarts to replace it whether or not a drop has been drawn.

The energy that reaches your shower is a fraction of what the meter records. The rest was spent keeping water hot at three in the morning.

Why 'reheating costs more' is wrong

The claim survives because it feels intuitive: heating cold water from scratch must cost more than topping up warm water. The arithmetic disagrees.

Reheating a tank once takes a fixed amount of energy determined by the mass of water and the temperature rise. Maintaining it for sixteen idle hours costs the standby loss for every one of those hours. For any tank in a Pakistani house, the second figure is much larger.

The claim would only hold for a tank so well insulated that its standby loss approached zero, which no domestic geyser is.

Thermostat setting

Set 55 to 60 °C. Above that you are heating water to a temperature you then mix cold back into at the tap, which is pure waste, and you accelerate scale formation on the element.

Below about 50 °C, stored water sits in the temperature range where bacterial growth becomes a genuine concern in a tank that is rarely fully drawn down. Fifty-five is the sensible floor.

Insulation and pipe runs

A tank jacket is cheap and cuts standby loss materially. So does insulating the first two metres of hot pipe leaving the tank, which otherwise acts as a radiator.

A dripping hot tap is a continuous draw of paid-for heat. Fixing one is worth more than it looks.

What to actually do

Switch the geyser on an hour before bathing and off immediately after — or fit a mechanical timer so you do not have to remember.
Set the thermostat to 55–60 °C.
Fit a tank jacket and insulate the first two metres of hot pipe.
Fix every dripping hot tap.
For a bathroom used briefly by one person, consider an instant heater — there is no tank to keep warm.
Where gas is available and safely ventilated, use it as primary and the electric geyser genuinely as backup.

What does not work

“Leaving the geyser on all day is cheaper than reheating it.”: It is roughly four times more expensive. Standby loss over sixteen idle hours far exceeds the energy to reheat the tank once.
“A bigger geyser is more economical because it holds heat longer.”: More water and more surface area means more standby loss, not less. Size the tank to what your household actually draws.

Frequently asked questions

How much does a geyser timer actually save?

Going from always-on to two heated hours a day takes a 2,000 watt geyser from around 540 units a month to about 120. At a high slab marginal rate that is a four-figure monthly saving from a device costing very little.

Is a gas geyser cheaper than electric in Pakistan?

On a per-unit-of-heat basis, generally yes. The counter-arguments are winter gas load shedding, which arrives exactly when the geyser is needed, and the real safety risk of an unvented gas heater in a bathroom.

Related guides

Why your winter bill can beat your summer one — winter, small one-off cost
Staying under 200 units and keeping protected status — all year, costs nothing

The numbers behind this

All 10 guides are ranked by value in the index. To see what your own house needs, run the efficiency audit.