Lime buildup in Water Heaters

Lime buildup in the tank

It is difficult to know what is in your water heater since water heaters do not have a view port to look inside. However, you can estimate how much lime buildup you have inside your tank by considering your water hardness and the age of your water heater. A 5 year old water heater with water hardness in the 20 grams range, could have a build up of about 5- 10 inches of sediment on the bottom of the tank. This also assumes you use your water heater like an average home in Tucson. In Tucson, our water hardness can be over 30 grams in a lot of areas.

Problems line buildup can cause

A popping or grawling sound from your water heater as it heats is a good sign that the tank has a build up of lime sediment on the bottom of the tank. Lime on the bottom of the tank can reduce heating efficiency of gas water heaters. For electric Water Heaters, the heating elements that are submerged in sediment are insulated from heating the water effectively.

Above you can see the effects of hard water on the insides of a water heater. Notice the white stufff on the bottom, that is lime flakes.

The most serious problem with sediment buildup is that sediment attacks the metal inside your tank. This will cause the tank to corrode over time and will leak from the bottom, often times causing serious water damage to your home, and often issues with mold.

How to solve lime buildup problems

Water Softener

One thing the helps reduce lime buildup in a water heater is a water softener. I water softener can almost eliminate any buildup that occurs in a water heater in Tucson. If you have a water softener to prevent this lime buildup, you need to make sure your water softener is always working properly.

Self Cleaning

Most water heaters produced these days claim to be self cleaning. While the idea is a sound one, the application is mostly a marketing tool. The self cleaning features claim they will keep the water stirred up inside the tank. This may work to some extent, but it does not seem to help our water heaters in Tucson much. The stirring of the water is supposed to be from the water entering the water heater, but all water heaters have always had a dip tube that extends to the bottom of the tank. This hasn't stopped the sediment buildup yet?

Replace the water heater

Once you have over 6 inches of lime build up in your water heater, the best solution is just to replace the water heater. The newer water heaters are more efficient and will pay for themselves over time. Water heaters are not very expensive to replace, and can usually be replaced by a professional within 2 hours.

Draining the water heater

The drain valve for the water heater is not located at the bottom center of the tank, but rather it is off to the side and up a inch or so from the bottom. Lime is heavier than water and tends to settle to the bottom of the tank. It doesn't move when you drain the tank, it just settles to the bottom of the water heater.
The actual size of the drain valve opening is about 1/2". Lime forms in chunks, a lot of these chunks are well over 1" in size. They tend to clog the drain valve and make draining it a time consuming process.
Not all the lime is loose, the heating elements are often completely coated with 1/2" of solid lime. Look at the lime buildup on the element to the right.

For these reasons, we do not recommend trying to remove lime from a water heater. More times than not, drain valves break and most of the lime is left in the tank anyways. It would be better to purchase a water softener, and save all the plumbing fixtures in your house to boot.