Along with your furnace and air conditioner, your water heater is one of the essential systems in your home. The average household consumes approximately 80-125 gallons of hot water every day. Your shower, sinks, and dishwasher all depend on it. However, your water heater becomes less reliable over time. Gradually, homeowners notice their hot water doesn’t last as long, even though they’re paying more for it. Unless they do something, eventually they’ll find there’s no hot water at all. Knowing when to replace your water heater helps you avoid these headaches. If you’re uncertain whether your water heater needs to be replaced, here’s what to look for.


Most water heaters last eight to twelve years, but with regular maintenance, some last as long as twenty. Regardless, every water heater becomes less efficient as it gets older. At a certain point, you’re better off replacing it than repairing it.

If you don’t know the age of your water heater, it’s listed on the tank in front of the serial number. Months are represented by letters. A stands for January, B for February, and so on all the way to L. The next two numbers are the year it was manufactured. “A14” is January, 2014, while “D17” is April, 2017, for example.

Less Hot Water

Every water heater accumulates sediment, which is why it’s equipped with an anode rod that runs down the center of the tank. Anode rods are made from aluminum or magnesium, elements that attract contaminants and corrosive minerals. However, if the heater has been operating for several years, the rod may be too saturated to capture additional loose particles. As a result, sediment will build up along the bottom and sides of the tank. This limits its capacity, which means less hot water.


Anode rods are designed to prevent corrosion. When they deteriorate, rust spreads through the system. In some cases, it becomes visible on the outside, normally around the seams or water lines, but sometimes on the surface of the tank itself. Once this happens, it’s only a matter of time before the heater fails.

Rusty Water

When your anode rod breaks down, water quality declines as rust and sediment build up inside your water heater. Instead of coming out clear and fresh, it becomes dark, sandy or cloudy. In some cases, you might notice a distinct metallic smell. However, since discolored water is caused by corroded piping as well as a corroded water heater, always run the hot and cold tap before calling a plumber. If they’re both rusty, it’s likely your water heater isn’t responsible.


Any water heater that’s sprung a leak should be replaced immediately. Leaks are generally caused by corrosion or thermal expansion. Over the course of multiple heating cycles, the metal around the joints, seams, and seals repeatedly expands and contracts, eventually resulting in fracture. Patching small leaks may extend its lifespan for a short time, but it only delays the inevitable need for replacement.


Like most appliances, water heaters are supposed to run quietly in the background. Noise is a sign your unit is malfunctioning, though not every noise indicates your heater needs to be replaced. Some can be repaired without any ongoing issues, while others only occur when your water heater is reaching the end of its lifespan. These include:

  • Rumbling. Steam bubbles often form underneath layers of sediment inside your water heater. As the water heats up, these bubbles can expand and burst, creating an audible rumble or “pop.” Adding a descaling product or flushing the tank will help mitigate the problem, but if it persists, then it’s probably time for a new tank.
  • Hissing. Hissing is a common issue with electric water heaters. As sediment builds up around the heating element, small bubbles can form inside them. As the temperature inside the tank rises, these bubbles vaporize and escape, like steam from a tea kettle.
  • Vibrating. Another sign of sediment buildup, vibrations occur when boiling water is trapped underneath layers of sediment and can’t escape. As the temperature rises, the energy from the bubbling water is transferred out to the tank, creating a distinct tremor.
  • Banging. When the water flowing through your pipes is suddenly forced to change direction, it creates a loud bang, also known as “water hammer.” It occurs whenever a valve closes or a pump shuts off abruptly. The water surges backwards, creating a pressure wave that can burst pipes and fittings. Though not necessarily a problem with your water heater, it should be investigated by a plumber as soon as possible.

Knowing when to replace your water heater not only helps you avoid sudden failures, disruptions, and water damage. Upgrading to a new, ENERGY STAR model saves money by reducing energy consumption over the long run. Upgrading to a tankless water heater lowers your operating costs and environmental footprint even further. Call a plumber as soon as you notice anything out of the ordinary. They’ll assess the condition of your water heater and let you know whether it’s time to invest in a new one.