No Hot Water After a Storm, Blackout or Holiday: The Restart Guide

These outages happen every storm season and every January, and this is the secret truth: a good portion need a restart, not a repair, and it fills a plumber’s phone. They interrupt the pilots, tariff windows, timers and pipework in known patterns and at known points. The restart guide, event by event, system by system, plus the essential short list of post-event symptoms that are not restart material and are where a professional is needed.

After A Storm: Wind, Water And Blown Flames

There are 3 ways that storms impact hot water systems. Gusty southerly changes are the number one assassin of gas pilot lights, so the number of “no hot water” calls increases the morning after the wild weather. The fix is just the standard relight, panel instructions, gas cleared, thermocouple warmed, and a system which relights and holds requires nothing more.

Burner compartments: wind-driven rain can wet a burner area on an outside unit, causing a pilot to be unable to light until the rain has dried; many systems that are “storm-killed” come to life after a dry day, while a persistent failure to light after drying indicates a problem that requires a service call, not another relight.

If a unit has been truly flooded, water over the controls or electrical components or burner, it is a complete no-no for a restart. Gas controls and electrics are impacted without anyone knowing it when a unit is submerged, and the moment post-storm stories get worse is when a flooded unit is relit and re-powered. Any flooded systems must be professionally inspected prior to restart, and the damage must be included in your insurance claim for the storm.

After A Blackout: The Scrambled Schedule

Electric systems seldom fail due to power failures, they are only disrupted. Complete the checklist sequentially.

The tariff window: if the outage coincided with your controlled-load heating hours, the tank simply missed some or all heating for overnight use; expect a normal service day tomorrow, and use the boost switch if available and required tonight.

The switchboard: one of the most common culprits after a restoration surge is the hot water breaker, a device you can see on the board. When the breaker resets after a few seconds, think of it as a hot water leak to earth; stop resetting it, schedule a trip to the electrician, and mention the blackout, as you’ve now diagnosed the problem.

Electronics: continuous-flow units can display error codes after power events; digital timers and controllers can lose the clock and begin a heating window at a time that isn’t designed, but usually return to normal after a power cycle (note if it doesn’t); and heat pumps occasionally enter protective lockout after a power event that is only cleared by power cycling, note if the code returns.

Then wait appropriately: restoration plus recovery time comes before judgement (for which we come to the calibration below).

Hours, Not Minutes

Real recovery times following restarts: gas storage reheats in about an hour, an electric element takes several hours to full tank, off-peak tanks may wait for tonight’s window, longer in winter. Judge a restarted system starting tomorrow morning, and not 20 minutes in.

After Water Main Works: Air And Grit In The Lines

If the water supply is interrupted by Sydney Water or by street works, the water will come back with souvenirs: air in the pipes and sediment stirred up by the street works. The symptoms are ominous, coughing and spitting taps, milky-white water, some taps do not have a proper flow, a continuous-flow unit won’t fire, and the cure is simple. Flush the air from the system by running the tap (first cold, then hot) continuously until it runs smoothly; if the flow from an outlet is weak, unscrew its aerator and run the water through it for a few minutes until it becomes smooth. After a few minutes, the cloudiness should be removed; if it is not, it is probably air or harmless sediment which will pass out.

The one additional check for continuous-flow units: they have a small inlet filter screen just for this purpose. If it’s clogged with debris from the mains, the unit will not get the minimum flow and will look like a “broken” unit, but really it’s just a clogged strainer, which is easy to clean by a professional, or a careful owner on the models that are accessible. Gravity-fed systems in older homes are the exception, as they are prone to airlocks; if spitting continues after a day, it’s a service call, not more flushing.

After Holidays And Vacancy: Waking The Sleeping System

Getting back to a cold house typically involves getting back to a system that someone (to their credit) had shut down before being gone, so the process of returning is mostly the reverse of leaving, but with two additional things. The sequence: water main back on slowly; electric hot water on at the board (and boost if tonight matters); gas systems returned from PILOT or OFF with the standard relight; then the recovery wait.

The two rules to keep in mind. First, use the taps: for water that has been in the system for weeks or longer, there is a need to purge, so run all water outlets until new water arrives, and while you’re at it, let the floor wastes and unused drains fill their traps. Second, for truly long vacancies, follow the Legionella logic: bacteria grow in warm, stagnant water, and a turned-off tank is exactly that after a month. Wait for the tank to reheat to the correct storage temperature of 60°C, the temperature specifically set to control Legionella, before treating the hot water as normal, and make sure the outlets get a hot flush after the tank has been reheated. One night of patience and it’s textbook procedure for the revival of any stored-water system.

What’s Not A Restart: The Red Flag List

There is a boundary to the whole concept of this guide, and here it’s clearly defined. These post-event symptoms are faults, not scrambles, and it is here where stopping the restart and starting the repair begins: a breaker that won’t hold after one reset (element earth leakage, the classic surge casualty); a pilot that lights but won’t stay lit after a proper procedure (thermocouple); a tank that is still cold after a full recovery window with power, gas and settings confirmed; any new leak from the tank base, fittings or a relief valve that now runs all the time (no longer dribbling); and a gas smell, which outranks all restart instincts in this article, valve off, ventilate, professional help.

The great thing about this: post-event faults are among the most predictable in the trade. The surge takes elements, the wind takes thermocouples, and the pattern (“blackout Tuesday, breaker won’t hold”) is usually enough to figure out the order of things before anybody can even get there.

Questions We’re Often Asked

How long after a blackout should I wait before deciding something’s actually broken?

For an electric tank, power up at the board, and then several hours for recovery, or the next off-peak window if controlled-load; gas storage, 1 hour or so after power. Cold water following that window, confirmed, is a real fault, and “still cold 24 hours after the blackout” is about as apt a sentence as you can say on the phone.

The storm knocked our power out and now the hot water breaker keeps tripping. Coincidence?

Not at all, surges are an electrical killer, making high currents flow through old insulating material and invariably causing failure. The re-tripping breaker is a safety device that is correctly refusing to power a bad element. It’s also one of the fastest hot water repairs; let them know about the storm when you book and they will follow the pattern to fix the tripping.

Who do I actually call after an event, SES, electrician, or plumber?

Division of labour: the SES (132 500) for storm emergencies, structural damage, flooding in progress. An electrician for electrical supply issues such as a dead switchboard and damage to a mains connection. A plumber for the hot water system itself (elements, gas components, valves, tanks); and a licensed gasfitter (any good plumbing outfit) for gas systems. If in any doubt, give a description of the symptom to the first person you call, as the trades are used to directing each other’s work.

We’re renting and the hot water didn’t survive the storm. Whose job is the restart?

The reasonable split: simple restarts, breaker reset or panel-instruction pilot relight, are fair for the tenants to try, just like any tenant would. If it fails again, or it was flooded, it is the landlord’s problem, and a hot water failure is on the NSW urgent repair list, so it is a legal obligation to do it, not a favour. Report it in writing the same day, record what restarts you made, and the clock starts from there.

Should I shut the system down before every trip, given the restart hassle?

Yes, the restart in question here is only minutes of work; and the alternative (a system that is left heated and pressurised in an empty house) is a real risk of flood and possibly waste, which the shutdown prevents. The pro move is made up of departure and return, matched up as a routine: main off, system down on the way out; valves on, relight/re-power, purge and patience on the way back. Ten minutes each way, and both ways of this article become non-events.

The Bottom Line

If the hot water shuts off immediately after a storm, blackout, mains interruption or holiday, assume it is the event before the equipment: relight the pilot after the power is back on, reset the tripped breaker one time, purge the air and grit, reverse the departure shutdown, and let the hours of recovery count before judgement. The majority of outages after the event are scrambles and have known resets. When the red flags fly, a breaker that won’t hold, a pilot that doesn’t stay, a failure of the tank to heat, anything that got wet, you’re holding a real but very predictable fault, and the quickest cure is to inform the plumber of what the sky, the grid or the street did first.

The Premium Sydney Plumbers team: licensed plumbers offering hot water system repair across Sydney, same-day service when available. Call 1300 026 452 at any time and we’ll help you get your hot water back up and running.