Storage Water Heater Leaking Water: 10 Key Reasons
Storage Water Heater Leaking Water: 10 Key Reasons
Introduction
Having a storage water heater leak can be a frustrating and costly experience. From damp false ceilings to water pouring down into the bathroom, such leaks are a common issue for homeowners with electric storage heaters installed above their false ceilings.
Some leaks occur as early as three years after installation, while others take over a decade to manifest. Understanding the causes can help prevent leaks and extend the lifespan of the heater.
Let’s explore the various reasons why your storage water heater may be leaking and what you can do to prevent it.
Cause 1: Corroded Mild Steel Inner Tank Due to Broken Lining
Most storage water heaters have an internal steel tank lined with a protective coating to prevent rusting. Over time, this lining can deteriorate due to wear and tear, exposing the mild steel underneath to water. Once the steel is exposed, it begins to rust, weakening the tank until it eventually develops leaks.
Prevention: Choose a high-quality water heater with a durable lining. Ariston uses titanium enamelling, while Rheem provides an inner tank with an exclusive vitreous enamel coating to protect against rust and corrosion.
Cause 2: Corroded Mild Steel Inner Tank Due to Depleted Sacrificial Anode Rod
A sacrificial anode rod is installed in most storage heaters to attract corrosive elements, preventing them from attacking the steel tank. However, this rod gradually dissolves over time. Once it is depleted, the inner tank becomes vulnerable to corrosion, leading to leaks.
Prevention: The anode rod should be inspected and replaced periodically, typically every 3 to 5 years, depending on water conditions and manufacturer recommendations. Ariston uses an enhanced magnesium anode, which is not available for sale separately, while Rheem provides self-sacrificing magnesium anode rods that may be available online.
Cause 3: Choked Drainpipe
When the drainpipe is choked, pressure inside the tank increases beyond its rated capacity. This excessive pressure can force water out through the weakest points, such as joints or seams, eventually leading to leaks or even bursting of the tank.
A common cause of choked drainpipes is when air-conditioning contractors repurpose them for condensation drainage. Another less common cause is improper installation by unlicensed handymen, who may seal the pressure relief valve discharge hole to prevent water from falling onto the false ceiling.
The high-end Rheem 85VP-65SVP Classic has a pressure rating of 10 bar (150 psi), while most Ariston square or slim models are rated at 7.5 bar (108.8 psi). The higher rating could explain why this Rheem model tends to last twice as long as many other heaters.
Prevention: Ensure that the drainpipe is free of obstructions and properly connected. Regular maintenance can help prevent pressure buildup.
Cause 4: Loose or Damaged Connections
Over time, fittings and pipes connected to the water heater can become loose or damaged, especially after a tank replacement.
To cut costs, some contractors offer cheaper replacement packages that involve only replacing the storage heater while reusing existing elbows, connection fittings, stop valves, double-check valves, and even the pressure relief valve.
This reduces labour time from the usual five hours to just two, saving about $100 in parts and another $100 in labour. Others skip replacing fittings due to a lack of tools and parts.
Unlicensed handymen, unfamiliar with proper plumbing techniques and lacking the necessary tools, typically just unscrew the two water inlet/outlet connections and attach them to the new tank. Charging as little as $150 for a one-hour job, this practice violates PUB regulations, creates a hazardous situation, and turns the installation into a potential ticking time bomb above your head.
Repeated unscrewing and tightening of fittings causes metal fatigue, leading to microfractures. Worn or stripped threads compromise the seal, increasing the likelihood of leaks. Over-tightening can also deform the threads or crack the fitting.
Prevention: Always hire a licensed plumbing company that explicitly states all touched fittings (usually within one metre of the tank) will be replaced. Demand to see the full submission document to PUB. Many companies falsely claim to use licensed plumbers for marketing purposes or engage one only for rubber-stamping.
Cause 5: Failed Gaskets Around Heating Elements
Storage heaters have heating elements that are sealed with gaskets to prevent leaks. These gaskets can degrade over time due to heat exposure, causing water to escape from around the heating element.
Prevention: If you notice water pooling near the heating elements, have a professional replace the gaskets before the leak worsens.
Cause 6: Cracked Internal Tank Due to Physical Impact or Manufacturing Defects
A crack in the internal tank, whether from impact or a manufacturing flaw, can cause water to leak. Sometimes, tiny hairline cracks develop over time due to stress from repeated heating and cooling cycles.
Poor handling of the tank during construction is a known issue that is difficult to control. These defects usually only become apparent after the developer’s defect liability period expires.
Prevention: Since this malpractice is not visible to the homeowner, it is beyond the user’s control. If you suspect a manufacturing defect, check if the heater is still under warranty and request a replacement.
Cause 7: Faulty Lever at the Pressure Relief Valve
The pressure relief valve is designed to release excess pressure from the tank. If the lever is faulty or stuck, water may continuously drip or leak.
Prevention: Regularly operate the pressure relief valve by lifting the lever slightly to ensure it releases water properly. If it does not function correctly or shows signs of leakage, it should be replaced.
Cause 8: High Water Pressure in the Tank Due to a Non-Functioning Pressure Relief Valve
If the pressure relief valve fails to open when pressure builds up, the excessive pressure can force water out of other weak points in the heater.
Prevention: A non-functioning pressure relief valve should be replaced immediately to prevent potential tank rupture. A licensed plumber should test the pressure and verify if the valve is operating correctly. If the reading is higher than the valve release rating, the valve is faulty and must be replaced before it causes the tank to crack.
Cause 9: Poor Maintenance Leading to Sediment Build-Up
Over time, minerals and sediments settle at the bottom of the tank. If not flushed regularly, this build-up can trap water, creating pockets of extreme heat that lead to localised corrosion and eventual leaks.
Prevention: Flush the storage heater at least once a year to remove sediment build-up. This also improves heating efficiency.
Cause 10: Aggressive Water Chemistry
Water with high acidity (low pH), high mineral content (hard water), or high oxygen levels can accelerate corrosion inside the tank, leading to premature failure.
If the pressure relief valve fails to open when pressure builds up, the excessive pressure can force water out of other weak points in the heater.
Prevention: Fortunately, this is not an issue in Singapore. Water supplied by PUB is of the highest quality and free from such problems.
Conclusion
A leaking storage water heater can result from a variety of issues, including corrosion, excessive pressure, poor maintenance, and faulty components. By understanding these common causes and taking preventive measures, you can extend the lifespan of your heater and avoid unexpected leaks.
Using only licensed plumbers for replacements, conducting regular inspections, and replacing worn-out parts in a timely manner can save you from costly repairs and water damage. If you notice any signs of leakage, addressing them early can prevent further complications. Always consult a qualified plumber for professional advice and repairs.
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