2 Ways Calcium Affects Your Tank-Style Water Heater

Posted on: 8 July 2015

Even with the invention of tankless water heating, tank-style water heaters are still a common fixture within most residential households. Whether your tank-style water heater is brand new or several years old, you've chosen to stick with it due to convenience and familiarity. Although tank-style water heaters certainly have their advantages, they are also severely affected by calcium in these two ways:

Anode Coverage

Your water tank's anode rod is a built-in defense against corrosive minerals in your water supply. Without an anode rod, lime and magnesium that enter your water tank will begin corroding your metal dip tube, heating elements (if you have an electric water heater), and tank lining. With the use of an anode rod, lime and magnesium instead attack the noble metal surrounding the rod instead of your tank's metal components.

However, calcium bicarbonate will collect on your anode rod. When enough calcium collects on your anode rod, it will prevent water—and corrosive minerals—from coming into contact with the rod. As a result, your anode rod will be rendered useless even though it may have several months of use left in it.

Luckily, it's easy to check whether or not calcium bicarbonate has encased your anode rod. To do so, you simply need to remove your anode rod from the top of your water tank by removing the 1-1/16" bolt from your lid. Pull the bolt out of your lid to examine your anode rod.

Even if your anode rod isn't completely coated with calcium bicarbonate, the existing buildup will still affect your anode's ability to prevent corrosion damage. However, completely replacing your anode rod because of a slight amount of calcium buildup can be a waste—especially if your anode is still fairly thick. Instead of replacing your rod, wipe away the calcium buildup with a rag. If any stubborn calcium remains on your anode after being wiped, then use a wire brush to remove it.

If a thick coating of calcium has already covered your entire anode rod, then the best option is to replace it. You can purchase aluminum or magnesium anode rods at nearly any home improvement store. Once you've made your purchase, install your new rod by covering the bolt threads with plumber's tape and screwing it into your water heater's lid.

Water Contamination

When water enters your tank, it's sent through your dip tube into the bottom of your tank where it is heated by either your heating elements or burner assembly. This design ensures that the heated water already inside your tank is forced through your tank's outlet pipe at the top of your tank when hot water is called for by your faucets or shower heads.

However, this design also allows calcium and other contaminants to settle at the bottom of your tank. Since the water being sent through your dip tube flows at a relatively fast rate, the buildup of contaminants at the bottom of your tank will be stirred up anytime your water tank refills. When this happens, contaminants at the base of your tank will be sent through your supply lines and out of your faucets.

Additionally, calcium that remains at the base of your tank for a long period of time will be constantly heated by your heating components. As a result, the calcium will turn into scale—which cannot be removed from your tank without the use of powerful cleaning agents.

Water contamination is easily prevented by periodically draining your water tank. Draining your water tank is a tedious process that requires adjusting your temperature and pressure relief valve, locating a suitable drainage field or gutter, and forcing air pockets out of your tank.

If these tasks aren't performed properly, then you will cause permanent damage to your water heater's internal components. For this reason, pay special attention to these tasks while draining your tank, or hire a professional water heater repair company to drain your water tank for you at least once a year. In addition to regularly draining your tank, you can install a water softener or reverse osmosis system to reduce the mineral content of your tap water.