Load-Shedding and Your Pool Pump: A Practical Guide

2026-09-26

Pool equipment is built to run on a steady supply of electricity. When load-shedding or a municipal outage happens, the pump stops, timers can lose their place, and the pool loses filtration and chlorination for as long as the power is off. None of that is a disaster on its own, but repeated outages add up, and the moment the power comes back can be harder on your equipment than the outage itself.

This guide covers how to plan around outages, what to check when the power returns, and what to think about if you are considering running the pump on backup power.

Plan run-time around your area's schedule

If your area has a published outage schedule, it is worth using. Check the schedule for your area with your supplier, which is either Eskom or your municipality, depending on who bills you for electricity.

A few principles help:

Split the run-time into blocks. Two or three shorter blocks spread through the day are more resilient than one long block. If an outage lands on one block, the pool still gets the others.
Place the blocks in windows that usually have power. Look at the times your area is scheduled to be off and set the pump to run around them.
Check the total still adds up. The pool needs enough hours to turn its volume through the filter at least once a day, more in summer. Our guide to how long a pool pump should run and what it costs explains how to work that out.
Make up lost time. Unplanned outages, such as a cable fault or a substation problem, cannot be planned for. When one knocks out a block, add the hours back later in the day or the next morning.

Timers that lose their setting

The timer is the part most affected by outages, and it is easy to miss when it has gone wrong.

A mechanical timer with a dial and pins simply stops while the power is off. When the power returns it carries on from where it stopped, so after a two-hour outage the timer is two hours behind the real time. After a few outages, a pump set to run in the day can be running at night.

A digital timer keeps time with a small internal battery. When that battery is flat, the timer can lose the time, the programme, or both, and fall back to a default setting.

Get into the habit of glancing at the timer after every outage. If it keeps drifting, a digital timer with a working backup battery, or one that sets itself, saves a lot of checking. If you are unsure whether the timer is wired correctly, have it looked at by someone qualified rather than opening the panel yourself.

Surges when the power comes back

When the supply is restored, the voltage can spike and dip for a short time. Motors, chlorinator power supplies, heat pump electronics and digital timers can all be damaged by this.

Two things reduce the risk:

Switch the equipment off during a long outage at its isolator, and switch it back on a few minutes after the power has returned and settled. Only do this if the switch is safe and easy to reach, and never with wet hands.
Surge protection fitted at the distribution board protects the pool circuit, and the rest of the house, from spikes. This is electrical work and must be done by a qualified electrician.

Do not open the distribution board or the pool equipment's wiring yourself. Water, electricity and a pump room are a dangerous combination.

When the pump loses prime

A pump that sits above the water level can lose its prime during an outage: the water drains back towards the pool and air takes its place. When the power returns, the pump spins but moves no water.

Signs include a pump basket with no water in it, a motor that hums or sounds different, no flow at the returns and a pump housing that is getting hot. A pump running dry can damage its mechanical seal in a short time, so do not leave it.

Switch the pump off.
Check the water level in the pool. It should be about halfway up the weir opening.
Open the pump lid and fill the pump basket housing with water from a bucket or hose.
Check the lid O-ring is clean, in place and lightly lubricated, then close the lid firmly.
Switch on and watch the basket. Air should clear and water should start moving.
If it will not prime after a couple of tries, switch off and leave it off.

A pump that loses prime regularly may have an air leak on the suction side or a worn lid seal. Our pool pump repair service is R850 for diagnosis and repair, with any parts quoted before they are fitted.

Salt chlorinators

A salt chlorinator only produces chlorine while the pump runs and water flows through the cell. Every hour lost to an outage is an hour of chlorine not made, and in summer that shortfall shows up as falling chlorine readings and dull water.

After the power returns, check that the control box is on and still set to the output you normally use. Many chlorinators wait for flow before they start producing, and some show a flow or low-salt warning until the pump is running properly. If outages have been frequent, test free chlorine and top up with a manual dose if it has dropped below 1 ppm. Our guide to cleaning a salt chlorinator cell covers keeping the cell producing well.

Heat pumps

Pool heat pumps are generally designed to protect their compressors, and many have a built-in delay before they restart after the power returns. Let that delay run. Switching a heat pump on and off repeatedly to hurry it along is hard on the compressor.

A heat pump also relies on water flowing through it, so it will not run until the pool pump is running and primed. After an outage, check that the heat pump's settings have not reset. Heat pumps draw a lot of power, so running one from a home backup system is rarely practical.

Running the pump on inverter or battery backup

Some homeowners want the pool pump on their backup system so filtration continues through outages. It can work, but there are things to consider before connecting it.

Start-up current. An electric motor draws much more current for a moment when it starts than when it is running. The inverter has to be able to supply that start-up surge as well as whatever else it is powering at the time.
Battery capacity. The pump's running energy comes straight out of the battery. Work it out the same way as a running cost: input kilowatts × hours = kWh, and compare that with what your battery can supply alongside the rest of the house.
Variable-speed pumps. These typically start gently and draw far less power at low speed, which makes them much better suited to backup systems than a single-speed pump.
Proper installation. Connecting a pool circuit to an inverter is electrical work for a qualified electrician, who will also check the installation suits the pump's figures.

Take the figures from your pump's nameplate and your inverter's specifications rather than a general rule, and ask your installer to confirm they match.

After a long outage

After an extended outage, or several in a row, work through this list:

Check and reset the timer.
Check the pump has primed and is moving water, and empty the weir and pump baskets.
Run the pump continuously for several hours to catch up on filtration.
Test free chlorine and pH, and correct them.
Brush the walls and floor, especially if the water has dulled.
Check the chlorinator and heat pump have restarted with their normal settings.
Check the filter pressure and backwash if it has risen.

Getting help

On our weekly pool maintenance service we check the timer and equipment on every visit, and help you set a schedule that fits the times your area usually has power. We run weekly routes across Centurion, Pretoria, Pretoria East and Midrand; see our Pretoria East pool services page for that side of the city.

If your pump will not prime, trips when the power returns or the timer keeps misbehaving, send us a WhatsApp on 081 577 5051 with a photo of the pump, the timer and the filter, and we will tell you what we think is going on.