Why Is My Hot Water System Leaking?
I'll tell you what I find more than anything else on the Northern Beaches — a corroded tank, a seized valve, or condensation you don't need to worry about. And I'll tell you what to do before I even pull into the driveway.
Last month my team got a call from a unit in Manly. The tenant said the carpet near the linen cupboard felt damp. "I just thought the carpet was damp from the bathroom," she told me. I pulled back the cupboard door and found a hot water tank with a slow pinhole leak running down the side. The sacrificial anode had never been replaced in ten years. Internal cylinder corrosion had eaten clean through the tank wall.
Up and down the Northern Beaches, from Dee Why to Manly, I see the same handful of causes for leaking hot water systems. Here's what they are and what I'd do about each.
- Tank corrosion. If the tank body itself is leaking, that's end of life. The glass lining has cracked, water hit the steel, and the corrosion won. No point patching. You need a new hot water system.
- Faulty TPR valve. That temperature-pressure relief valve dribbles or spurts water down the discharge pipe. Usually a quick swap, takes under an hour, no tank replacement needed.
- Loose or corroded connections. The threaded fittings at the top loosen over time from thermal expansion. In coastal suburbs salt spray speeds it up. Tighten or replace a short section of pipe. Easy fix.
- Failed drain valve. The plastic or brass valve at the bottom cracks or doesn't seat properly. A slow drip that usually stops if you open and re-close it fully.
- Pressure spikes. Washing machine valves slamming shut, or thermal expansion without an expansion tank. Forces water out through the TPR valve or stresses the tank welds.
- Condensation. Beads across the surface in humid weather, disappears when the water warms up. Not a real leak. I get called out for it all the time.
What to do while you wait for me
- Turn off the power. Electric system — flip the breaker. Gas — turn the gas valve to off.
- Shut the water. The cold water inlet valve on the pipe going into the tank. Turn it clockwise.
- Find where it's coming from. Wipe the tank dry and watch where moisture reappears. Top means a connection. Bottom means the tank or drain valve. The discharge pipe means the TPR valve.
- Contain it. Bucket and towel to stop floor damage.
- Call an emergency plumber. I'll tell you over the phone whether it's a valve swap or a full replacement, and I'll give you a price before I turn up.
Northern Beaches reality check
Properties close to the coast in Manly, Dee Why, and Brookvale see tank life 2-3 years shorter than inland. The salt air eats external fittings and flue components on gas units. I've swapped units in Freshwater that rusted out in six years.
Older homes in Mosman and Frenchs Forest have units in internal cupboards. Protected from salt spray but still 15-20 years old and leaking from age-related internal corrosion. The tricky part — a leaking tank in a confined space damages floors and walls before anyone notices. Check your cupboard monthly.
Frequently asked questions
Can I repair a leaking hot water tank myself?
No. If the tank itself is leaking, you must replace it. The internal lining has failed and the steel is corroding. Patching it or using a sealant is dangerous and will fail. If a valve or connection is leaking, a licensed plumber should handle the repair.
How long can I use a leaking hot water system?
Replace a leaking tank immediately. A tank leak worsens without warning and can flood your home. If a valve or fitting is leaking, you can use the system temporarily, but have it repaired promptly to avoid water damage.
Why is my hot water system leaking from the top?
A leak from the top of the unit points to a loose or corroded inlet or outlet connection, or a failed pipe nipple. It could also be the cold water supply line or a shutoff valve. These repairs do not require tank replacement.
Does home insurance cover a leaking hot water system?
Most home insurance policies cover sudden water damage from a leaking system like damaged flooring or walls, but not the cost of replacing the faulty system itself. Check your policy details or speak to your insurer.
Leak's getting worse? Let me sort it.
Same-day diagnosis across the Northern Beaches. I'll tell you what's wrong, give you a price upfront, and have it fixed fast. No pressure, just a fair quote.
Related reading
- No Hot Water? 7 Common Causes and How to Fix ThemIf your water has gone cold instead of leaking.
- Gas vs Electric Hot Water: Which Is Right for You?If replacement is needed, choose the right system.
- How Long Should a Hot Water System Last?Is your system approaching end of life?
- Hot Water System Maintenance ChecklistCatch small issues before they cause leaks.
- What Size Hot Water System Do You Need?Choose the right replacement capacity.