My hot water is hotter than normal
If the shower has started running hotter than it used to, don't just turn up the cold and live with it. Water that's hotter than normal is a scald risk, especially for children and older people, and it usually means a part has failed. The good news is the fix is often small. Here's what causes it and what to do.
Why hot water suddenly runs hotter
Failed tempering valve
The tempering valve keeps bathroom water at no more than 50°C. When its internal parts wear out or clog, it can let through water at full tank temperature. This is the most common cause.
Faulty thermostat
On an electric storage system, a thermostat that sticks on can overheat the water. You may also notice steam or the relief valve discharging.
Settings changed
Continuous flow and heat pump systems have temperature settings on a controller. A power cut, a new controller or a well-meaning visitor can change them.
Cold supply problem
If something restricts the cold water to a mixer or tempering valve, the mix tips hot. Low cold pressure at one tap can do it.
What to do now
- Tell everyone in the house, and run the cold first when filling a bath.
- Check the water temperature at the bathroom tap with a kitchen thermometer after running it for a minute. Over 50°C is too hot.
- Look at the relief valve drain outside. Steam or constant discharge with very hot water means the system should be checked soon.
- Don't adjust the tempering valve or open the thermostat cover yourself. Thermostats sit behind electrical covers.
How we fix it
We test the temperature at the outlets and at the heater, check the tempering valve, thermostat and controller, and find which part has failed. You get clear options and a fixed price before any work starts, usually a tempering valve service or replacement, or a new thermostat. See our tempering valve page and safe hot water temperature guide.
In southern Eastern Suburbs homes
Tempering valves in older homes around Matraville, Maroubra and Botany are often well past the age when makers recommend replacing them, and grit from old pipes clogs their strainers. A valve that has quietly failed is the most common reason we find bathroom water running too hot.
Why locals call us
- Local to Matraville and the southern Eastern Suburbs
- Free on-site quotes, with a fixed price before any work starts
- Lifetime labour warranty on our workmanship
- 100+ five-star Google reviews
- Licensed plumbers and gasfitters (Lic. 398171C)
Common questions
Why is my hot water suddenly so hot?
The most common cause is a failed tempering valve, which lets full-temperature water through to the bathroom. A faulty thermostat or changed settings are the other usual culprits.
Is it dangerous if my hot water is too hot?
Yes. Water over 50°C at the bathroom can scald quickly, especially children and older people. Get it checked soon.
Can I turn down my hot water system myself?
Storage systems need to keep water at 60°C or more to control bacteria, and thermostats sit behind electrical covers. It's a job for a licensed plumber.
How much does fixing a tempering valve involve?
Often just a service or a replacement valve, which is usually a short job. We'll give you a fixed price before starting.
Related help: tempering valves, safe hot water temperature guide, hot water repairs, relief valve dripping and TMV testing. Local pages: hot water Matraville, hot water Maroubra, hot water Botany and hot water Kingsford.