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Seeing water leaking from the overflow pipe can be worrying, but it’s a common issue in many homes.
You didn’t touch anything, the system still heats water, and yet the hot water system’s overflow pipe keeps leaking.
So what’s actually going on? This blog explains why hot water leaks from the overflow pipe, what it means, when it’s normal, and when it’s not.
What Is the Overflow Pipe on a Hot Water System?
Every hot water system has a safety outlet, and that outlet is the overflow pipe. Its job is simple. It releases water when the pressure or temperature inside the tank becomes unsafe.
When everything is operating normally, the overflow pipe stays dry, but when something pushes the system beyond safe limits, water is discharged on purpose. That’s why seeing water there doesn’t always mean the system is broken.
The key question is this: Is it just doing its job, or indicating an underlying problem?
Normal behaviour looks like this:
- A brief leak during heating cycles
- Occasional discharge after heavy hot water use
Warnings to watch out for include:
- Water discharges continuously rather than stopping on its own
- The hot water overflow pipe keeps leaking when no taps are being used
Why You Shouldn’t Ignore a Hot Water Overflow Pipe Leak
When it runs constantly, the system is telling you something isn’t right and that pressure or temperature is no longer being managed properly.
Ignoring it can lead to:
- Higher water bills as wasted water continues to drain away
- Increased energy usage from the system working harder than necessary
- Valve failure caused by ongoing internal stress
- Tank damage that weakens the system over time
- Full system breakdown that requires replacement
Why Is My Hot Water System Dripping from the Overflow Pipe?
1. High Water Pressure Inside the System
This is the most common cause in Australian homes. As mentioned previously, when the water pressure is too high, the system protects itself by releasing water through the overflow.
Many homes experience pressure changes throughout the day, driven by morning and evening demand, and seasonal fluctuations.
The thing is, hot water systems are designed to handle only a certain pressure range, and anything beyond that forces water out.
2. Faulty Temperature and Pressure Relief Valve (TPR Valve)
The TPR valve is a key safety component. It controls:
- Internal pressure
- Water temperature safety limits
When it fails, the hot water system overflow pipe becomes a constant outlet instead of an emergency release.
3. Excessive Water Temperature
Hot water systems are designed to operate within safe temperature limits. When water gets too hot:
- Pressure rises quickly
- Safety valves activate
- Water is released through the overflow pipe
Signs of a problem include:
- Overflow discharge occurs shortly after the system heats up
- Steam, hissing, or unusual noises coming from the system
Is It Safe to Use Hot Water If the Overflow Is Leaking?
Usually, yes. However, “safe” doesn’t mean the issue should be ignored. When the overflow is leaking constantly, the system is operating under extra strain, and that ongoing stress increases the risk of a complete system shutdown.
The problem won’t resolve itself, and it’s best not to delay an inspection for hot water repairs in Parramatta.
Conclusion
A hot water system leaking from the overflow pipe isn’t always a cause for alarm, as sometimes it’s normal. Other times, it’s a warning that a bigger issue is developing. Either way, paying attention early helps prevent higher bills, water waste, and avoidable system damage.
If your overflow pipe is dripping constantly, running when no hot water is in use, or causing concern, our team of plumbers in Parramatta is ready to help. We’ll identify what’s really going on and get your system back to safe and reliable operation.
Call Hero Plumbing at 02 9137 8549 to speak with a local expert, or book through our online form.
