What are the most common hot water system problems?

No hot water, leaking tanks, low pressure, rust-coloured water, and noisy systems are common hot water issues. Causes range from failed heating elements and tempering valves to sediment buildup and corrosion. Most problems can be repaired if diagnosed early.

When your hot water stops working, it disrupts more than just your shower routine. Whether you’re facing a cold tap, low pressure, or strange noises from the tank, your system is trying to tell you something. Understanding these early warning signs can help you avoid costly repairs or full system failure.

This guide covers the most frequent hot water issues we see across the Sunshine Coast and how to address them, safely and effectively.

No Hot Water

This is one of the most common complaints and usually the easiest to diagnose.
In electric systems, a tripped circuit breaker or failed thermostat is often the culprit. Start by checking your switchboard, especially after recent storms or power surges.

For gas systems, check the pilot light. If it’s gone out, it may be due to a faulty thermocouple or gas flow issue. In homes using LPG bottles, common in areas like Cooroy and Pomona, make sure the bottle isn’t empty.

Many continuous flow or tankless systems display a fault code on the unit. This code can be the key to a quick fix, provided it’s read and interpreted by a qualified technician.

Leaking Tank

Leaks around the base of the tank often point to internal corrosion—and unfortunately, this usually means the tank has reached the end of its lifespan. In these cases, replacement is more cost-effective than repair.
However, not all leaks mean disaster. Drips around the pressure relief valve, inlet, or drain line may just need new seals or minor tightening.

Areas like Noosaville and Tewantin can experience faster tank wear due to varying groundwater quality. Routine servicing helps prevent mineral buildup and premature corrosion.

Low Water Pressure

Low pressure is often caused by a blocked tempering valve, sediment buildup in the tank, or aging plumbing. In some cases, it’s simply a pressure-limiting valve set too low.

If your pressure drops during showers or fluctuates between taps, flushing the system and servicing valves can restore flow. This issue is common in older systems across Doonan, where pipe scale can form inside hot water lines over time.

Rusty or Smelly Water

Brown or discoloured water coming from your hot tap is usually a sign that the tank’s sacrificial anode is breaking down. This rod protects the tank from rust and should be replaced every 4–5 years. If neglected, the tank walls begin to corrode.

Bad-smelling water—especially with a sulphur or ‘rotten egg’ odour—often means bacteria are forming inside a warm, unused tank. This is common in holiday homes or in outlets used infrequently. A tank flush and new anode typically clears the issue.

Noisy System

A tank that gurgles, knocks, or pops during heating is almost always dealing with sediment buildup. Minerals settle at the bottom of the tank and insulate the heating element, causing the metal to overheat unevenly.

This is a known issue in harder water areas like Gympie and Cooran. It doesn’t usually cause immediate damage but can shorten the life of the tank if not addressed.
Annual flushing and tank maintenance can reduce or eliminate these noises.

When to Call a Licensed Hot Water Plumber

Some issues—like a cold shower or noisy pipes—might seem minor. But small faults often lead to full system failures if left too long. If your system is:

• Leaking
• Not heating properly
• Tripping the power or safety switch
• Over 10 years old and underperforming

…it’s time to bring in a licensed professional.

Flaregas Plumbing is fully qualified to diagnose and repair all major hot water system brands across the Sunshine Coast and hinterland. We carry replacement parts, offer expert advice, and can recommend a system upgrade if needed.

Hot water systems often give early signs before they fail—but only if you know what to look for. Whether you’re in Noosa, Pomona, Doonan, or Gympie, recognising common issues early can save you time, money, and frustration.

Need help fast? Flaregas Plumbing offers prompt, professional hot water repairs Sunshine Coast-wide.