Pump running costs, and why your tank is already a battery.

What a pump actually costs to run

The sum is simpler than most energy advice makes it sound. Three numbers, all of which you already have or can read off the pump.

Rated kilowatts, times hours run, times the rate per kilowatt hour.

A 1.5 kW pump running two hours a day uses 3 kilowatt hours a day, or roughly 1,100 kilowatt hours a year. A 0.75 kW pressure pump cycling on and off through the day might only accumulate an hour of actual running. The rated kilowatts are on the nameplate. The rate is on your bill. The number nobody has is the hours, which is the whole problem, and we will come back to it.

We do not publish cents per kilowatt hour here, because your retailer sets your rate, the rates differ between plans and networks, and a figure copied from someone else's bill would only mislead you. Take it from your own bill. What matters more than the number is whether it is a single number at all, because on a time of use tariff it is not.

The bit that has changed: off peak is not just overnight any more

The traditional advice is to pump at night. That advice is now partly out of date, and following it blindly can mean paying more than you need to.

There is so much rooftop solar on Australian networks that the middle of the day has become a problem the networks want to solve by encouraging consumption. Several New South Wales tariffs now price a midday window as cheaply as the small hours, and sometimes more cheaply.

Last checked: 14 August 2026. Ausgrid windows from Ausgrid's time of use pricing page. Endeavour and Essential business tariff codes and windows compiled by WATTever. The note that Endeavour's overnight off-peak rate sits above its flat rate is from the Endeavour network price list effective 1 July 2026, read against the AER's 2026-27 default market offer. Network windows typically change on 1 July, and your retailer may apply its own windows on top of the network's. The tariff code on your own bill is the only authority for your site.

The practical upshot for a farm with solar: pumping at midday may now be cheap twice over, once because you are using your own generation instead of exporting it for a small feed-in payment, and again because the network window itself is cheap. That is a better answer than a 2am timer, and it is easier on the neighbours.

The tank is the storage

Here is the whole idea in one line: you are not trying to use less water, you are trying to move the moment you pay for moving it.

A header tank, a storage tank feeding troughs by gravity, or a pressure tank on the house all do the same job as a battery for this purpose. You fill it when power is cheap and draw from it when power is expensive. The differences from a lithium battery are all in your favour:

• You already own it, so the payback period on the storage itself is zero.
• It does not lose capacity over ten years.
• It has no round-trip efficiency loss worth worrying about. Water pumped up stays up.
• It keeps doing its original job at the same time, which is holding water.

The limits are real and worth stating. Storage only helps to the extent you have headroom in the tank, so a tank that sits nearly full all the time gives you nothing to play with. Gravity feed needs actual height, and a pressure pump that runs on demand cannot be scheduled at all unless there is a storage tank between it and the tap. And if your water use is dominated by irrigation that has to happen at a particular time for agronomic reasons, the timing is not yours to move.

Why none of this works without a level reading

This is where most off-peak pumping plans quietly fail, and it is the reason this page exists on a monitoring site rather than an energy one.

Scheduling requires knowing how much room you have. Without a level reading, pumping is reactive: someone notices the pressure has dropped, or a trough is low, or the house tank sounds hollow, and the pump goes on right then. That moment is set by when a person happened to notice, which on a working property is disproportionately late afternoon and early evening, which is precisely the expensive window on every tariff in the table above. The default behaviour of an unmonitored pump is to run at the worst possible time.

With a level reading you get the three things a schedule needs:

• Headroom. How much you can put in tonight or at midday tomorrow, so you fill in one cheap block instead of three expensive top-ups.
• Draw rate. How fast the tank actually empties, which tells you how far ahead you can safely pump and when you would need to override the schedule.
• Proof the pump worked. A pump that ran for four hours and moved no water is a run-dry, a blockage or a burst line. On a timer alone you find out days later, and you have paid for every one of those hours.

That last one usually matters more than the electricity saving. Our page on pump dry-run protection covers what happens to a pump that runs without water, and how tank level sensors work explains the measurement itself.

Setting it up, in the order that works

1. Find your tariff code on the bill and write down the cheap windows. Do this first, because it decides everything after it, and because you may find you are on a flat rate where none of this applies.
2. Note the pump's rated kilowatts from the nameplate.
3. Measure the level for a fortnight before changing anything. You need the draw rate, and you need to know your real starting point rather than an assumed one.
4. Pick one cheap block that covers a normal day's draw with margin, and set the timer for it.
5. Set a low-level alert below your comfortable minimum, so an unusual demand day or a leak overrides the schedule instead of leaving you short.
6. Check the trace after a month. If the tank is hitting the alert regularly, the block is too short. If it never drops below three quarters, you are pumping more than you need.

A controlled load circuit is worth asking your retailer about at step one. Those rates are usually the cheapest available, the trade being that the retailer decides when the circuit is live rather than you. For a pump filling storage that trade is often acceptable, because the tank absorbs the uncertainty. It needs separate wiring, so price it as an electrical job.

Where this sits

If you want the tariff mechanics themselves, our sister site explains how time of use tariffs work, with the peak and off peak windows network by network. If your interest is the whole property's energy profile rather than the pump specifically, dairy refrigeration, irrigation scheduling and sheds together, Rural IoT covers the whole-farm view.

Questions people ask