Hard Water: Signs, Testing and Fixes

What makes water hard

Rain is soft. As it soaks through soil and rock it dissolves minerals, mostly calcium and magnesium, and those two are what a hardness test measures. Well water in limestone country tends to be the worst, but plenty of city systems deliver hard water too.

Labs and test kits report hardness in grains per gallon (gpg) or in milligrams per liter (mg/L), which is the same as parts per million. One grain per gallon is about 17 mg/L. Penn State Extension uses this scale:

The USGS uses a simpler version that calls anything up to 60 mg/L soft and anything above 180 mg/L very hard. Either way, the number on your report is what matters, not the label.

Hardness vs alkalinity

People mix these up because both show up on the same test strip. Hardness is the calcium and magnesium. Alkalinity is the water's ability to neutralize acid, mostly from dissolved bicarbonate. Hard water is often high in alkalinity too, but they are separate readings, and a softener changes hardness, not alkalinity.

Hard water signs

You usually don't need a test to suspect it. The giveaways:

• White crust on faucets, showerheads and the inside of the kettle.
• Spots and film on glasses and dishes after the dishwasher, and cloudy stains on eyeglasses rinsed at the tap.
• Soap and shampoo that won't lather, and a film left on skin and in the tub.
• Laundry that comes out dingy, with detergent curds in the washer.
• A water heater that pops and rumbles as it heats. That's water boiling under a layer of scale on the tank bottom.
• Showerheads with some nozzles plugged and the spray going sideways.

Orange or brown stains are a different problem. That's iron, and a softener alone may not handle it. See iron in well water.

What hard water does to your house

Most of the cost is hidden. Scale builds up on pots, in pipes and inside water heaters, and Penn State notes it can shorten a water heater's useful life. On an electric heater the lower element gets buried in scale and burns out early. On a gas tank the scale insulates the bottom of the tank from the burner, so it runs longer for the same hot water.

Hard water also cuts how well soap works, so you use more detergent, more shampoo and more dish soap to get the same result. Fixtures and glass shower doors get a white haze that ordinary cleaners barely touch.

If your heater already sounds like popcorn, a flush helps. Our water heater flush guide walks through it.

Is hard water bad for you?

No. Calcium and magnesium are essential nutrients, and Penn State says these minerals have no adverse health effects and are essential daily nutrients. EPA doesn't set a drinking water limit for hardness at all; it isn't on the secondary standards list.

The health question cuts the other way. Softening swaps the hardness for sodium, adding about 7.5 mg of sodium per quart for each grain per gallon removed. If someone in the house is on a low-sodium diet, ask a doctor, and consider leaving one kitchen tap on unsoftened water.

How to test water hardness

You have three ways to get a number, from cheapest to most accurate:

1. Test strips. Dip, wait, compare the color. Good enough to tell soft from very hard.
2. A drop-count titration kit. You add drops until the sample changes color, and the count gives you grains per gallon.
3. A lab test. Penn State recommends an independent lab, which isn't expensive and keeps you from being oversold.

Many softener dealers offer a free hardness test. That's fine as a starting point, but get your own number before you sign anything. Step-by-step instructions are on how to test water hardness at home. If you're on a private well, test for iron and bacteria at the same time; our well water testing guide covers the full list.

Fixes for hard water, ranked

1. Live with it (under about 7 gpg)

Penn State says water below 7.0 gpg probably won't cause major scaling or soap film. At that level, clean fixtures with white vinegar or a citric acid cleaner, flush the water heater once in a while, and skip the equipment. Acid dissolves scale; harsh scrubbing just scratches the glass.

2. An ion-exchange water softener (most homes above 7 gpg)

This is the fix that actually removes hardness. Water runs through resin beads loaded with sodium, the resin grabs the calcium and magnesium, and every so often the softener flushes itself with salt brine to recharge. Each regeneration uses about 50 gallons of water, so mention it to whoever services your septic system.

HomeGuide puts a salt-based softener at $1,200 to $3,800 installed, with salt or potassium running $50 to $150 a year. You don't have to soften everything. Toilets and outdoor taps can stay on hard water, which saves salt. See how a water softener works and water softener cost before you shop.

3. Salt-free conditioners

These don't remove calcium and magnesium, so a hardness test after install reads about the same as before. What they claim to do is change how the minerals form scale. HomeGuide lists them at $1,500 to $4,500 installed. If what bothers you is soap that won't lather and spotty dishes, a salt-free unit won't fix that. Our salt-free vs salt softener comparison goes deeper.

4. Reverse osmosis for drinking water

RO removes calcium and magnesium along with many other contaminants. Most homes use it at one kitchen tap for drinking and cooking, not for the whole house, because whole-home RO runs $4,800 to $10,000 installed. It pairs well with a softener; it doesn't replace one.

What doesn't fix it

Special detergents, shampoos and spray cleaners for hard water treat the symptoms. Magnetic and plug-in gadgets are the other thing to be wary of. Run a hardness test before and after any device; if the number didn't move, the hardness is still there.