My Water Heater Is Popping and Rumbling. Is That Bad?

What Is Actually Happening Inside

Hard water carries dissolved calcium and magnesium. Every time that water is heated, some of those minerals precipitate out and settle to the bottom of the tank, building a layer of sediment over months and years. On a gas unit, the burner is directly underneath that layer.

Sediment insulates the water from the heat source. The burner has to run longer to reach temperature, which wastes gas or electricity, and the tank bottom gets considerably hotter than it was designed to. Water trapped in and under the sediment layer flashes to steam and forces its way up through it, and that is the popping and rumbling you hear.

Riverside County sits in one of the harder water regions in the country, which is why this is such a routine finding here. Tanks in this area frequently fall short of their rated life, and sediment is usually why.

What It Costs You

Three things, in increasing order of expense. Efficiency first: an insulated tank bottom means longer heating cycles and higher bills for the same hot water. Capacity second: sediment occupies volume, so a 50 gallon tank with a significant sediment layer effectively holds less, which is why hot water runs out faster than it used to.

Tank life third, and this is the expensive one. Overheating the tank bottom accelerates corrosion of the steel and the glass lining that protects it. Once that lining fails, the tank corrodes through, and a tank that has corroded through cannot be repaired. That is a replacement.

What to Do About It

Flushing the tank removes the sediment and is the single most effective maintenance you can do. It is done through the drain valve at the base, and on a tank that has never been flushed it can make a noticeable difference to both noise and recovery time. Annually is the right interval in this area.

On a tank that has gone many years without flushing, the sediment can be hardened enough that a standard flush will not clear it, and the drain valve itself may clog during the attempt. That is worth knowing before starting, and it is one reason many homeowners have it done rather than doing it themselves.

The longer-term fix is treating the water. A softener removes the calcium and magnesium before they ever reach the tank, which protects the water heater along with your dishwasher, washing machine, and fixtures.

Also Worth Checking

• The age of the unit, usually decodable from the serial number on the label
• Whether the water runs rusty or brown from the hot side only
• Any moisture, drips, or rust staining around the base
• Whether hot water runs out faster than it used to
• The temperature setting, since running hotter accelerates scaling
• When it was last flushed, if ever

Call a Plumber If

• The noise is accompanied by rusty water from the hot side
• There is moisture or rust staining at the base of the tank
• The unit is over ten years old and has never been flushed
• The relief valve is discharging
• Hot water capacity has dropped noticeably

Related Services

Water Heater Repair  •  Water Softener Installation  •  Water Heater Installation