Care guide
Hard water and your appliances
Updated · Fixwell Appliance Repair editorial
Short answer
Hard water carries dissolved calcium and magnesium. When it heats or evaporates, those minerals form scale on valves, heaters and spray arms. Large parts of the U.S. Southwest, Plains and Midwest have hard water, according to the USGS, and appliances there see more scale-related repairs.
What scale does inside appliances
Scale insulates heating elements so they run hotter, narrows valve openings and spray holes, and roughens seals. The result is poorer cleaning, slower fills and earlier part failures.
- Dishwashers
- Cloudy glasses, blocked spray arms and scaled heaters.
- Washers
- Scaled inlet valves and heating elements on models that heat water.
- Ice makers
- Scaled valves and molds, cloudy ice.
How hardness is measured
USGS classification of water hardness as calcium carbonate.
| Milligrams per liter | Classification |
|---|---|
| 0 to 60 | Soft |
| 61 to 120 | Moderately hard |
| 121 to 180 | Hard |
| More than 180 | Very hard |
Your water utility's annual water quality report usually lists hardness.
Reducing scale damage
Use rinse aid
Helps dishwasher water sheet off glass.
Descale regularly
Dishwashers, washers and coffee makers have descaling or clean cycles.
Replace refrigerator filters on schedule
Some filters reduce scale and protect the ice maker valve.
Consider a softener
Whole-house softeners protect all appliances; check local rules on discharge.
Signs scale is causing problems
White film on dishes
Especially glasses.
Slow fill
Scaled inlet valves.
Crusty spray arm holes
Visible white deposits.
Small, cloudy ice cubes
Scaled ice maker valve.
Which appliances suffer most
Anything that heats water or lets it evaporate collects scale fastest. Dishwashers top the list, because they heat water on every cycle and spray it through small holes. Front-load washers with internal heaters, coffee makers, steam ovens and refrigerator ice makers follow.
Refrigerator ice makers are a special case. The inlet valve opens for a few seconds at a time, and scale gradually narrows it until cubes come out small and hollow or the valve sticks open and leaks. A refrigerator filter that is replaced on schedule protects the valve, and some filters are designed to reduce scale.
Water heaters are not covered on this site, but they are often the costliest scale casualty in a hard water home, which is one reason many households in very hard water areas choose whole-house softening. Check your appliance manuals for any guidance on softened water.
Questions: hard water and your appliances
Does a water softener void appliance warranties?
Not generally. Check your appliance manual for its guidance on water hardness and softened water.
How do I find my water hardness?
Your utility's water quality report, a home test strip, or the USGS hardness map for a general picture.
Which cities have hard water?
Our city guides note local water hardness where the utility publishes it.
Will vinegar descale my dishwasher?
Many people use it, but check the manual first. Some manufacturers recommend a specific cleaner and warn that acids can affect seals over time.
Does hard water affect detergent?
Yes. Minerals reduce how well detergent works, so dishes and laundry may need more detergent or a booster. Softened water usually needs less.
This guide is general information, not professional, legal or insurance advice. Appliances, water conditions and local rules vary. Have a technician diagnose your appliance, and follow the manufacturer's instructions.
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