Hard Water Effects On Water Heaters: What The Sources Say

Penn State Extension describes the symptom of hard water as a grayish white sediment, called scale, that forms anywhere water is heated. A water heater is one of those places. Virginia Tech Extension adds that mineral scaling in water heaters can increase heating costs by reducing their efficiency, and that hard water can reduce the efficiency and life span of water heaters. Neither source gives a percentage, and neither does this page.

What The Deposit Is

Penn State Extension says the minerals behind it build up on contact surfaces. Its water softening article says that when calcium and magnesium permeate water, they build up on contact surfaces, possibly plug pipes and damage water heaters. The same article says that from a health standpoint these minerals have no adverse effects. So the case against it at the heater is about equipment and efficiency, not about drinking the water.

Virginia Tech Extension describes the same deposit in more places: on the inside of pipes, cookware and plumbing fixtures as well as appliances such as water heaters, with excessive scaling in pipes able to reduce water flow and pressure.

What The Water Heater Manuals Say

The manuals we read mention cleaning, but give no schedule. State Water Heaters’ residential electric manual says that periodic draining and cleaning of sediment from the tank may be necessary, and its element-replacement instructions say to remove any sediment from or around the element opening. It does not state an interval. Our maintenance page is where service is arranged.

For tankless units the manufacturer detail is more specific. State’s manual for its THR-series gas tankless heaters describes a scale prevention technology it calls X3256, offered on some models, which it says reduces the formation of scale in the heat exchanger. The same manual says specific water conditions, such as excessive iron or manganese levels, may impact its efficiency, and tells the reader to consult a water quality expert. That is one maker’s product statement for one range, not a general claim about tankless units.

What You Can Do About It

Virginia Tech Extension’s advice is to match the treatment to the problem. It says water hardness levels less than 7.0 gpg, or 120 mg/L, generally do not require treatment, and that treatment is only necessary when the hardness level is causing a problem for the homeowner. If scale forming in your water heater is the issue, it suggests considering softening only the water that is to be heated. Our water softener and water heater guide covers what that involves, including the effects on the heater itself.

Is Your Water Affected?

That depends on your supply, and this page does not know it. Different addresses in Lancaster County are served by different public utilities, and some by private wells, so a figure for one place is not a figure for another. We publish no mineral-level figure for Lancaster-area water. What the units mean is in our units and classes guide, where to find your own number is in our testing guide, and what manufacturer documents say about coverage is in our manufacturer documents guide.

What This Page Will Not Tell You

It will not tell you how much shorter a tank’s life is. A specific percentage once appeared on this site and was withdrawn because no source supported it. Virginia Tech says hard water can reduce a water heater’s efficiency and life span; it gives no figure, so the honest version has none. Nor will it state a flushing interval, because the manuals we read say periodic cleaning may be necessary without saying how often. For the repair side, see water heater repair in Lancaster, PA and the popping and rumbling noise guide.

Mineral Buildup And Water Heater FAQ