Hard water
What hard water does to a water heater
Hard water carries dissolved calcium and magnesium. Heat drops them out as scale, and a tankless heater's narrow passages are where that shows first.
Where you see it
White crust on faucets and showerheads
Spots on glasses and shower doors
A film inside a kettle
Scale on the heat exchanger, where you can't see it
Hardness, in plain numbers
Find your water's number
Hardness is dissolved calcium and magnesium, counted in grains per gallon (gpg). Your utility's yearly water report lists it, and a test strip shows it in a minute. Then pick your band.
Soft
Little scale builds up. A tankless heater still gets a yearly look, but it rarely needs descaling on a schedule.
What you see: clean fixtures and glass
For the heater: check the inlet screen yearly
Moderately hard
Scale shows up slowly, first as a faint film on the showerhead.
What you see: a light film on glass and chrome
For the heater: a flush once a year is the usual interval
Hard
White crust collects on faucets and spots dry on glasses. Over time, scale can narrow the passages inside a heat exchanger.
What you see: crust at the aerator and showerhead
For the heater: flush it every year, or as your manual says
Very hard
Scale builds quickly. Flush at least yearly, and ask us whether a scale filter or a softener ahead of the heater makes sense in your house.
What you see: crust that returns soon after you clean it
For the heater: more often than yearly in some homes
Bands follow the U.S. Geological Survey's hardness scale. Your heater's manual sets the maker's flush interval, and it comes first.
What to do about it
Four ways to deal with hard water
They aren't exclusive. Many homes do the first, and some add a second.
Flush the heater
Clears the scale that has built up. It's what the Flush plan does, once a year.
A scale filter
Sits on the line ahead of the heater and changes how the minerals behave. We can talk through it and fit one if you choose.
A softener
Swaps the hardness minerals out of the water for the whole house. It needs salt and a drain, and it is a larger job.
Test first
A strip or a lab report tells you your number. Everything else depends on it.
Your number
Three ways to find your hardness
You don't need us to tell you. We're glad to read it with you once you have it.
Ways to get the number
Read your water utility's yearly water quality report
Use a hardness test strip from a hardware store
Send a sample to a water-testing lab
Ask us to test it at a visit
Questions about hard water
Is the water in Rio Rancho hard?
Water in this part of New Mexico is usually hard, but it varies by neighborhood and by source. Your utility's report or a test strip gives your own number.
Does hard water damage a tank heater too?
Scale collects in tank heaters as well, mostly at the bottom of the tank. A tankless heater has narrower passages, so scale gets in the way sooner.
Do I need a softener?
Not always. A flush handles the heater; a softener treats the whole house. We'll tell you which makes sense once you have your number.
Want a second opinion on your heater?
Text a photo of its label and the crust on your faucet.