No hot water? What to check before you call a plumber

Begin with a safety check rather than the switchboard

Before touching anything, look for visible water around the cylinder, damaged wiring, scorching or unusual smells. Keep children and other occupants away from the affected area. Water on the floor may make nearby electrical equipment unsafe even if the appliance appears to be off. Do not step through water to reach a switch, and do not touch wet electrical fittings. If there is immediate danger, leave the area and seek emergency help.

If you smell gas, leave immediately. Call the gas supplier or emergency services from a safe remote location, not beside the appliance or inside the affected building. Do not operate switches, use a phone in the affected area or attempt to investigate the source. A hot water fault can wait until the gas hazard has been made safe. Subsequent repairs need an appropriately licensed gasfitter.

Use this short sequence to organise your observations

The numbered sequence is intended to gather useful information, not to repair the heater. You can stop at any stage and call for advice. There is no benefit in repeating checks when access is difficult, the installation is unfamiliar or you feel unsure. A photograph of the visible model label and a clear description of the symptoms can be enough to start a useful conversation.

Avoid running taps repeatedly while testing. Brief observations are usually enough to establish whether water flows and whether different outlets behave similarly. If there is a visible leak, do not delay arranging assistance while working through the sequence. The priority is preventing exposure to hot water, electricity or gas and limiting further damage where that can be done safely.

1. Look from a safe position for leaks, damaged equipment or unusual smells, and stop if you find a hazard.
2. Check whether cold water is available at the kitchen and another accessible outlet.
3. Briefly compare hot water at separate outlets, noting whether it flows cold, runs lukewarm or does not flow.
4. Check your water supplier's outage information if both hot and cold supplies are affected.
5. Check electricity outage information and ask your electricity retailer about controlled hot water supply interruptions where relevant.
6. Read any externally visible appliance message without opening covers or attempting a reset.
7. Contact the appropriate licensed professional with the observations you have gathered.

Separate missing water from water that is not heating

If cold taps work but nothing comes from the hot side, a plumbing or valve problem is a possibility. If water flows normally from the hot tap but stays cold, an electric storage system may have a supply, element or thermostat fault. Rheem's fault guide makes this distinction because the next professional involved can differ. These patterns narrow the enquiry, but they do not establish the cause without inspection.

Where hot and cold water are both absent, check the water supplier's current outage information. In Auckland, Watercare asks customers with no running water to check outages before reporting the fault. If there is no known public interruption, a residential plumbing assessment may be appropriate for a private supply problem. Tell the plumber whether the loss was sudden, followed other work or began after someone operated an isolation valve.

Check supply information without attempting electrical repairs

An electric storage cylinder may be affected by a general electricity outage or an interruption to a separately controlled hot water supply. Ask the electricity retailer whether a known issue could explain the symptoms. A house can have lights and working sockets while its hot water heating supply is unavailable, so the presence of power elsewhere does not settle the question. Keep any advice tied to your own supply arrangement.

You may note a switch or breaker position from a dry, safe place, but do not reset a tripped breaker. Do not open the cylinder's electrical cover, test wiring or adjust an internal thermostat. WorkSafe says tripped breakers, particularly safety switches, should not be reset before an electrician checks them. Any component that has become wet also needs an electrician's safety assessment before it is used again.

Look for a fixture problem before condemning the heater

When the kitchen has hot water but the shower does not, the heater is not the only possible source of trouble. A mixer, local valve or temperature control issue may affect an individual outlet. Describe whether the affected tap gives only cold water, fluctuates during use or has lost flow. Note any recent change to the shower head or mixer, because that history may help the plumber identify what needs checking.

Tap and mixer repairs may be more relevant than replacing the cylinder when the problem is localised. Do not dismantle the fitting or change concealed controls to test that theory. If the water is unexpectedly very hot, keep people away from the affected fixture and arrange a temperature assessment. A delivery fault should be corrected at its cause, rather than masked by changing the storage thermostat.

Consider demand and recovery without assuming a fault

A storage system can run short after unusually heavy use. Think about whether the change followed overlapping showers, a bath, visitors or a different household routine. If hot water returns after the system has had its normal opportunity to heat, demand may be part of the explanation. That does not rule out a developing fault, especially if the available hot water has noticeably reduced compared with similar use in the past.

Record the pattern rather than guessing a recovery time. Cylinder capacity, heating input, electricity control and starting water temperature all affect the result. The hot water cylinder replacement guide can help if your household now needs a different system, but a diagnosis should come before a replacement decision. A unit that has stopped heating needs investigation even if it is also smaller than you would choose today.

When to call a licensed plumber for missing hot water

For hot water cylinder repairs, provide the system type, visible model information, when the problem began and whether hot water flows at any outlet. Mention leaks and electrical symptoms before routine performance details. A plumber can investigate water supply, valves, cylinder leakage and delivery controls. An electrician deals with electrical supply and heating components, while gas appliance faults need an appropriately licensed gasfitter. Some investigations require coordination between trades.

Restricted plumbing and gasfitting work must be carried out by someone authorised for that work. Check current practising licences through the Plumbers, Gasfitters and Drainlayers Board. If you rent, tell the landlord or property manager promptly and explain any immediate hazard. Keep photographs and a brief record of the symptoms, but do not take risks to document equipment hidden behind covers or located in an unsafe space.