Water build-up around the tank, visible sediment, excess noise and cooler water temperatures are all signs of a failing a water heater. The age of the water heater is also an important indicator of when a water heater may fail.
Most water heaters more than 10 years old are contenders for replacement, especially if they are located in an area that can receive major damage if the tank starts to leak. To determine the tank's age, locate the serial number that is printed on the manufacturer's sticker. The serial number contains a code that represents the date, so reference the owner's manual or manufacturer's website to understand the code.
Rust or other sediment present in the hot water entering the home is another sign of a failing water heater. The pipes may rust as well, so it is important to determine the cause of the sediment before replacing the water heater.
An excess of noise or a rumbling coming from the water heater is a sign that the sediment in the bottom of the tank has hardened, which reduces the heater's efficiency and can cause damage to the tank, causing leaks. A build-up of water around the water heater is an indicator of a small leak in the tank. Determine the exact cause of the leak by checking all of the fittings and pipes before replacing the water heater.