7 Signs of Hard Water in Your Home (and What It Does)

Hard water is invisible until it leaves a mark. You do not taste it, and a glass of it looks like any other glass. What you notice is the white crust on a faucet, the cloudy film on the dishes and the water heater that has started to sound like a pot of popcorn. All of them are the same cause, and all of them can be checked in about ten minutes without any equipment.

Sign 1: White, crusty buildup on faucets and showerheads

Hard water leaves its minerals behind when it dries. A drip on the faucet becomes a white ring, and over weeks the ring becomes a crust. In a showerhead, the crust grows in the spray holes until the spray goes uneven or sideways. Rubbing it off with vinegar works, and it comes back. A faucet aerator that clogs every few months is the same problem.

Sign 2: Spots and a film on glassware and dishes

Dishes come out of the dishwasher with white spots, or with a cloudy film on glasses that no rinse aid removes. The water has dried on the glass and left its minerals. It is the sign people notice first, and the one they most often blame on the dishwasher.

Sign 3: Soap scum that will not stay gone

Soap reacts with the minerals in hard water to form a sticky scum. It shows up as a film on shower glass, a ring in the tub and a residue on tile that returns within days of cleaning. It also means more soap goes into every wash for less lather, and that laundry can feel stiff and look dull.

Sign 4: A noisy or rumbling water heater

This is the one that costs real money. In a tank water heater, the minerals settle out as scale at the bottom of the tank. That scale insulates the water from the burner or the elements, so the heater has to work longer to heat the same water. As water gets trapped under the scale and boils, the tank rumbles and pops.

Scale also builds up in the heat exchanger of a tankless heater and narrows the passages that the water flows through. It reduces flow, triggers error codes and shortens the life of the unit. In both cases, an annual flush helps, and a softener removes the cause. If your heater is already noisy, see our page on water heater repair.

Sign 5: Appliances that scale up fast

Coffee makers, kettles, steam irons, humidifiers, dishwashers and washing machines all heat or evaporate water, and all of them collect scale. If your kettle needs descaling every month, or your washing machine's heating element has a white shell on it, you have the same cause at a smaller scale. Appliances in hard water homes often have shorter lives for exactly this reason.

Sign 6: Water pressure that drifts down

Scale builds up inside pipes and in the small passages of valves and fixtures. Over years it narrows them. In an older home with galvanized or copper pipe you may notice weaker flow at the far end of the house, in the showers or at an outdoor tap. In a newer home with PEX the scale is less of a problem inside the pipe, but fixtures, valves and appliance inlets still clog.

Sign 7: Dry feeling skin and hair, and soap that will not rinse

Many people notice that soap seems to leave a film on skin and hair, and that it takes longer to rinse. The reason is the same reaction that makes soap scum. Whether this bothers you is a matter of preference rather than something wrong with the plumbing, but it is a common reason people notice their water is hard in the first place.

How to check your water in ten minutes

1. The bottle test. Fill a clear bottle one-third with tap water, add a few drops of plain liquid soap, shake it and look. Hard water makes few suds and a cloudy mix. Soft water makes plenty of suds and stays clear.
2. The faucet look. Check the base of the faucet and the aerator for white scale.
3. The glass look. Run a glass through the dishwasher and look for a film or spots.
4. The heater sound. Listen to the water heater when it is heating. Rumbling or popping is a sign of scale.
5. The report. If you are on city water, look up your utility's annual water quality report, which gives the hardness. If you are on a well, a laboratory test tells you what is in it.

None of these is a measurement, but together they tell you whether it is worth getting one.

What to do about hard water

There are two sides to it: treating the water and looking after what the water has already affected.

• Treat the water. A salt-based water softener removes the calcium and magnesium so it never reaches the heater, the dishwasher or the fixtures. It is installed at the main line, with isolation valves, a bypass and a drain. Our page on water softener installation explains what the job involves.
• Flush the water heater. A tank heater benefits from an annual drain and flush. A tankless unit should be flushed with descaling solution on the schedule the manufacturer gives. In hard water, do it more often.
• Clean fixtures and aerators. Vinegar soaks clear aerators and showerheads. It is a fix for the symptom and it will be back, but it keeps things working.
• Replace parts that scale has killed. A heating element or an anode rod in a hard water home may be gone sooner than expected.

If your problem is grit, cloudiness or a chlorine taste, rather than scale, a filter is the answer rather than a softener. Our guide on softeners and filters explains the difference.

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