What should a landlord record when hot water is intermittent at only one tap?

When one tap runs hot and cold but other outlets behave normally, a clear record can prevent an unnecessary boiler visit and help the right tradesperson arrive prepared. Note the exact outlet, the timing and flow pattern, what happens at other taps, recent plumbing work and any scalding risk. Do not ask a tenant to dismantle a mixer or open the boiler.

A one-outlet problem often points towards the tap, mixer, local pipework or a restriction near that outlet. It does not prove the boiler is fault-free, but it changes the first questions worth asking.

The short answer

• Record which tap is affected and whether the cold side is normal.
• Ask what “intermittent” means: delayed, pulsing, suddenly cold, weak, or only during other water use.
• Compare another hot outlet at a similar time without running both together.
• Note recent tap, bathroom, kitchen, boiler or mains-water work.
• Record any leak, fault code, unusual boiler behaviour or scalding incident.
• Keep the tenant to observation and ordinary controls; arrange a competent plumber or Gas Safe registered engineer as appropriate.

Start with the exact outlet

“The hot water is intermittent” is too broad for useful diagnosis. Record the room, the fixture and the type of outlet: kitchen mixer, basin mixer, bath tap, thermostatic shower or another fitting. Note whether the problem is on the hot side only, on both supplies, or only at a particular handle position.

If the property has more than one bathroom, include the floor and a simple location such as “rear first-floor basin”. This avoids confusion during a visit and helps identify whether the outlet is likely to be close to or far from the hot-water source.

Define what intermittent means

Ask the tenant to describe the sequence in their own words and then record it plainly. Useful descriptions include:

• water starts hot, turns cold and then becomes hot again;
• water is warm only when the tap is opened fully;
• the flow pulses or becomes noticeably weaker;
• the first use of the day is slow, but a second use is normal;
• temperature changes when a toilet, washing machine or another tap is used; or
• the problem occurs only at a shower setting or mixer position.

Record how long the outlet runs before the change and roughly how long the change lasts. A short phone video can show the flow and any visible boiler display without asking the tenant to perform repeated or risky tests.

Compare other outlets safely

Ask whether hot water is normal at the kitchen sink, another basin and, where relevant, the shower. Make comparisons one outlet at a time first. Running several outlets together changes the available flow and can create a different symptom.

If every hot outlet is affected, the hot-water source, incoming mains supply or a system-wide control becomes more relevant. If one outlet alone is affected while the others remain stable, a local restriction, tap cartridge, mixer valve, hose, aerator or service valve is more likely.

That is a direction for investigation, not a diagnosis. A competent plumber should confirm the cause before parts are ordered.

Record the hot and cold flow separately

At an ordinary basin or sink mixer, note whether cold flow is strong and steady while hot flow is weak or pulsing. If both are poor, a shared local fitting or supply issue may be involved. If the problem appears only when hot flow is reduced, a combi boiler may also be operating near its model-specific minimum demand rate.

Do not ask the tenant to measure scalding water with their hand. A simple description of flow and stability is enough for the first report. Any temperature measurement should use a suitable method and be left to a competent person where there is a risk of injury.

Note when the problem happens

Timing can separate a local outlet fault from shared demand. Record:

• time of day and whether it is the first hot-water use after a long gap;
• whether central heating is on;
• whether a washing machine, dishwasher, toilet or another tap is operating;
• whether the problem follows a water-supply interruption;
• whether it is worse at very low or very high tap flow; and
• whether the weather or incoming-water temperature appears to change the pattern.

One accurate example is more useful than repeatedly recreating the fault. Ask the tenant to stop testing if the water becomes dangerously hot, the outlet leaks or the boiler displays a warning.

Check the history

Record the date the problem was first reported and whether it began suddenly or gradually. Include recent replacement of the tap, mixer cartridge, shower head, hose, boiler or any nearby pipework. Also note decorating, kitchen or bathroom work that may have disturbed an isolation valve or flexible connector.

If the mains supply was recently turned off, say when it returned and whether other taps spluttered. Debris released during plumbing work can sometimes collect in an outlet screen, but the fitting should not be dismantled by an unqualified tenant.

Photographs and video that help

Useful images show the complete tap or shower, any visible make or model, the flow at the problem moment, leakage around the fitting and the boiler display while the outlet is running. Photograph labels only when they are accessible without removing panels.

Do not ask for a photograph inside a boiler casing, behind a fixed shower valve or from a position that exposes the tenant to hot water, electricity or a fall. The aim is to preserve evidence, not to turn the tenant into a repairer.

Look for immediate safety concerns

Escalate promptly if the temperature becomes uncontrollably hot, a child or vulnerable person uses the outlet, there is a significant leak, water reaches electrical equipment, or the fitting cannot be used safely. If anyone is scalded, the NHS advises cooling the injury under cool running water for 20 minutes as soon as possible and seeking the appropriate medical help.

A gas smell, carbon-monoxide alarm or suspected combustion problem is not a one-tap troubleshooting issue. Follow emergency gas guidance, leave the property when necessary and call the National Gas Emergency Service on 0800 111 999.

Landlord responsibility and response

For private renting in England, GOV.UK says landlords are responsible for repairs to basins, sinks, baths and other sanitary fittings, including pipes and drains, as well as heating and hot water. Housing law and procedures differ across the UK, so use the rules for the property’s nation and the tenancy circumstances.

A dated report should record when the landlord became aware, the effect on the tenant, the safety assessment, the advice given and the appointment made. Keep copies of messages, contractor findings and completion records. The seriousness and household circumstances determine how quickly a response is needed.

Who should attend first?

Competent plumber

If one tap or shower is affected while other hot outlets are normal, a plumber can inspect the accessible outlet, cartridge, aerator, hose, isolation valves and local pipework. Give them the fitting make, photographs and comparison notes.

Heating engineer

If several hot outlets fluctuate, the boiler fails to recognise demand, a fault code appears or the problem follows boiler work, arrange an appropriately qualified heating engineer. Work on a gas boiler itself must be carried out by a Gas Safe registered engineer competent for that appliance.

Both may be needed

A local restriction can interact with a combi boiler’s minimum hot-water flow. The plumber may confirm the outlet restriction while the heating engineer verifies boiler operation. A good record prevents each from seeing only half of the pattern.

What not to ask the tenant to do

• Do not remove the boiler casing.
• Do not dismantle a concealed mixer or thermostatic valve.
• Do not bypass an anti-scald control.
• Do not repeatedly run water at an unsafe temperature.
• Do not force stiff isolation valves or filling controls.
• Do not turn a one-outlet report into instructions for internal boiler repair.

A concise report template

• Property and outlet: address, room, floor and fitting type.
• Reported: date, time and tenant’s description.
• Pattern: delayed, weak, pulsing, hot-cold or linked to another outlet.
• Comparison: which hot and cold outlets are normal or affected.
• Duration: time to first warmth and time until the fault appears.
• Recent changes: plumbing work, appliance work or mains interruption.
• Evidence: safe photographs, video, boiler display and any leak.
• Risk: scalding, vulnerable occupier, loss of usable washing facilities or water near electrics.
• Action: advice given, contractor booked and follow-up date.

Useful context for the contractor

Include the boiler make and exact model, but do not assume it is responsible. State whether it is a combi, a system boiler with a cylinder or another arrangement if known. Add the outlet make and model, and whether temperature changes only at low flow or when another draw-off opens.

Our guide to information to give a boiler engineer helps organise appliance details. Landlords can also use our tenant boiler-fault record checklist when the symptoms extend beyond one outlet.

The practical conclusion

For intermittent hot water at one tap, record the outlet-specific pattern before assuming a boiler fault. Safe comparisons with other taps, the hot and cold flow, timing, recent work and any risk usually show which professional should attend first.

Keep the tenant’s role to reporting and ordinary use. A clear, dated evidence trail supports a faster repair while protecting the tenant from unsafe dismantling or repeated scalding tests.