Is Soft Water Bad For Water Heater? September 8, 2022 08:55

Is Soft Water Bad For Water Heater?

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There are many things that can shorten the life of your water heater. Neglect, corrosive fumes, and high water pressure are all usual suspects. One thing you may not know is that water softeners are often the most common cause of premature water heater failure.

Water softeners are important for people who live in areas with hard water. Hard water contains minerals, most notably calcium and magnesium. When mixed with soap this can cause a filmy residue and can damage clothes, dishes, and leave users a general feeling of “unclean.” Water softeners removing the calcium and magnesium by replacing them with sodium in a mineral tank with ion exchange. No longer does soap coagulate and leave film, however water softeners can shorten the lifespan of your water heater.

Is hard water bad for the water heater?

Hard water is water that contains a high mineral count of magnesium, gypsum, and/or calcium. These minerals aren’t harmful to consume. In fact, they’re in most of the food you eat daily. But in high concentrations in water, they leave behind limescale. This is where the trouble with a water heater starts.

The temperature inside a water heater tank allows for the formation of limescale from hard water. The limescale settles along the tank floor. This sediment layer lowers the energy efficiency of a gas water heater, since this is the place where heat from the burners is transferred into the tank. An insulating layer of sediment makes this more difficult, forcing the water heater to run longer and drain more power. Flushing the tank fixes this, but it’s only a stopgap measure. The buildup will start again unless the hard water problem is stopped at the source.

How long does a water heater last with hard water?

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The average service life of a tank water heater is 8-12 years. One of the most common reasons why a water heater needs to be replaced is corrosion inside the tank. To prevent corrosion, most water heaters are designed with an anode rod that is inserted into the tank and essentially absorbs most of the corrosive elements. In other words, the anode wears out to protect the metal lining of the water heater tank.

When a water softener system is installed, it removes the “hard” minerals and replaces them with “softer” ones such as sodium. Soft water can actually corrode the water heater anode faster. When the anode wears down, the corrosive elements will move on to the tank. So if left alone, a water softener system can actually shorten the lifespan of a water heater.

Water heaters are appliances that heat the water you use in your home. They normally last about 8-12 years. Made of metal and constantly heating water, this appliance will eventually corrode. In order to prevent this from happening too soon, anodes are placed inside the heater. These are designed to corrode and should be checked typically every six years to see if they need to be replaced. Once the anode is corroded “down to the wire” your water heater is at risk of rusting and forming a leak.

Softened water corrodes these anodes at a much faster pace. The salt that replaced the hard minerals accelerates this process. If you have a water softener, you should be checking your anodes for replacement every year.

The main reason that water softeners can shorten the life of your water heater has to do with the anode rod. While many people have never heard of the anode rod, it plays a major role in keeping a water heater up and running. The anode rod is typically made out of aluminum or even magnesium and, without it, your water heater would start leaking well before a water heater with its anode rod still in place. Without getting too technical, water heaters will eventually succumb to corrosion from the water itself. This happens because water and steel simply don’t get along. Corrosive minerals and the minor electrical current created inside a water heater all lead to the water heater eventually failing. The anode rod attracts the corrosive materials and lets them corrode it first. It sacrifices itself to extend the life of the water heater.


So how does this relate to the water softener? Basically, the water softener operates by replacing minerals that make the water “hard” such as calcium and magnesium with sodium. This process increases the conductivity and corrosiveness of the water thus speeding up the corrosion of the anode rod. Once the anode rod is gone, the water will begin corroding the tank itself and that will eventually lead to tank failure. If would like a more detailed description of the anode rod and its function, you can click here.

How to protect my water heater?

Luckily, there’s an easy solution to getting the most out of your water heater. If you have a water softener system, you should have the anode rod of your water heater inspected and replaced more frequently. This is a fairly simple process – and certainly much cheaper than replacing the entire water heater unit.


Never take chances

While water softeners are necessary for areas where hard water is plentiful, it’s important to take into consideration the effect it can have on your water heater. Water heaters are just as important to the modern home, and if taken care of on schedule you can prevent them from breaking down before their time has come. Checking your anodes is the best thing you can do to prevent rust and the leaking that follows.

None of this means that you shouldn’t install a water softener or consider getting rid of the one you have. There are people who have had a water softener for years without any issues. We would like to note that while many industry professionals recommend replacing the anode rod every few years, recent water heater models make it very difficult for the anode rod to be replaced. Each manufacturer can have different sized anode rods made out of different materials and they may be accessible from different areas on the water heaters. So if you do feel like you would like to replace the anode rod yourself, we suggest contacting the manufacturer, who will be able to give you the best information about your specific model.