Why Is My Water Heater Leaking? Common Causes and Fixes

If you are wondering why your water heater is leaking, the cause is usually one of a few things: a faulty drain valve, a failing temperature and pressure relief valve, loose water line connections, or corrosion inside the tank itself. The first three are often repairable. A tank leaking from its body because of internal corrosion cannot be repaired and needs to be replaced.

A leaking water heater is not something to leave. For fast, honest water heater repair in Calgary, R N T Plumbing and Heating is available 24/7. We provide upfront pricing, a free plumbing inspection with every service, and a 5-year warranty on all parts and labour.

Where the water is coming from tells you how serious the problem is. The sections below walk through each cause.

First, Is It Actually the Water Heater?

Before assuming the tank is leaking, confirm the water is actually coming from the heater and not from a nearby source. Condensation on the tank, a leak from an overhead pipe dripping onto the unit, or a nearby appliance can all look like a water heater leak. Wipe the tank dry, place paper towel around the base, and check where the water reappears.

Once you have confirmed the heater is the source, identifying where on the unit the water is coming from points to the cause.

Common Causes of a Leaking Water Heater

A Faulty Drain Valve

The drain valve is located near the bottom of the tank and is used to flush sediment. If water is leaking from this valve, it may simply be loose, or the valve itself may be worn and need replacing. This is often a straightforward repair.

The Temperature and Pressure Relief Valve

The temperature and pressure relief valve, often called the T&P valve, is a safety device that releases water if pressure or temperature inside the tank gets too high. If water is leaking from this valve, it may be doing its job in response to excess pressure, or the valve itself may be failing. Either way this should be assessed by a technician, because a T&P valve issue can indicate a dangerous pressure problem inside the tank.

Loose or Corroded Water Line Connections

The hot and cold water lines connect at the top of the tank. Over time these connections can loosen or corrode, causing water to leak from the top of the unit. Tightening or replacing the affected connection often resolves this.

Internal Tank Corrosion

This is the most serious cause. Over years of use, the inside of a water heater tank corrodes, especially in a hard water city like Calgary where sediment accelerates the process. Once the tank wall corrodes through, water leaks from the body of the tank itself. A tank leaking from its body cannot be repaired and must be replaced. If the water is coming from the base or the side of the tank rather than a valve or connection, internal corrosion is the likely cause.

How to Tell If It Is Repairable

The location of the leak is the best early indicator:

• Leaking from the drain valve: often repairable
• Leaking from the T&P valve: assessment needed, sometimes repairable
• Leaking from the water line connections at the top: often repairable
• Leaking from the body, base, or side of the tank: not repairable, replacement needed

In this region, hard water accelerates sediment and mineral buildup inside tanks, which shortens their lifespan and makes internal corrosion more common than in cities with softer water.

What to Do Right Now If Your Tank Is Leaking

A leaking water heater can cause significant water damage quickly, so act promptly:

• Turn off the cold water supply valve at the top of the tank to stop water flowing in
• For a gas unit, turn off the gas supply valve
• For an electric unit, turn off the breaker
• Do not attempt to repair the tank body yourself
• Call a licensed technician to assess the unit

Repair or Replace?

If your tank is under ten years old and the leak is from a valve or connection, repair is usually the right call. If the tank is ten years or older, or the leak is from the tank body itself, replacement is typically the more cost-effective long-term choice. Most hot water tanks last 9 to 12 years, and Calgary’s hard water can shorten that. A good technician gives you an honest written assessment of your specific unit rather than pushing a replacement you do not need.

Get Your Leaking Water Heater Assessed

Call (825) 883-9264 or book online. Serving Calgary, Airdrie, Okotoks, and Strathmore.