Is It Normal for Water Heaters to Make Knocking Sounds?

Water heaters are among the most critical and hardest-working home appliances. They ensure a steady and continuous hot water supply for various activities, including bathing, cooking, washing dishes, doing laundry, cleaning, and space heating. Different types of water heaters are available for residential use. 

Occasionally, homeowners hear their water heaters make knocking sounds and wonder if it is a cause for concern. Generally speaking, any noise coming from an appliance is a cause for concern, and water heaters are no exception. It usually indicates that the unit is not working efficiently and something is wrong with it.

It is common and normal for a water heater to make popping or knocking sounds. Let us look into detail what causes a water heater to produce a knocking sound and why it is essential to call an experienced plumber to handle the issue.

Why does a water heater make knocking sounds?

A knocking sound emanating from the water heater is most likely due to the accumulation of a thick layer of sediments or mineral deposits at the bottom of the tank, known as scale. Sediment build-up occurs in every water heater over time, but the issue is more prevalent and frequently occurring in areas with hard water. 

If the water source has a higher concentration of dissolved minerals, it can cause severe damage to the pipes, plumbing components, and water-using appliances. When the water is heated, the process leads to the separation of minerals from the water. Those minerals then accumulate in the tank, forming a thick layer at the bottom near the burner. These sediments harden over time and trap water underneath them. Once there is enough mineral build-up, as the burner heats the water, the water inside bubbles up and escapes the sediment, creating the knocking sound as the sediment bangs against the water heater walls.

Scale build-up reduces the efficiency of the heater. As a result, it struggles to heat water efficiently and overheats the tank, causing it to deteriorate, leak, or burst.

How to stop water heater knocking sounds?

Flushing the sediments from the water heater is the best way to stop the knocking noises. Annual water heater flushing involves clearing out all the scale deposited at the bottom and preventing the sediments from banging against the heater walls. Homes with a hard water supply should flush the water heater more frequently. Homeowners may also consider adopting ways to treat hard water, like installing a water softener.

Those who haven’t flushed the water heater in a long time and hear the knocking sounds should consider flushing the heater right away. A plumber can properly flush the water heater and also take care of other tasks like spotting signs of aging, corrosion, and wear and tear to extend the water heater life and ensure its optimum functionality. 

Homeowners should not ignore the knocking sounds to prevent severe issues and expensive repairs in the future. If flushing does not lessen the knocking sound, a plumber can suggest other options to resolve the problem.

With over 25 years of experience, American Discount Plumbing has offered expert plumbing service and repair in Phoenix, Arizona, and surrounding cities at affordable rates for both residential and commercial properties. We are a licensed, bonded, and insured plumbing company offering 24-hour emergency service. We provide lasting general plumbing, water leak detection and repair, toilet repair, pipe repair, and water heater repair or replacement solutions. Call 602-883-2787 today!