aesthetic
Water Hardness (Calcium/Magnesium) in your water
Is Water Hardness (Calcium/Magnesium) in drinking water dangerous?
It depends on the level and how long you're exposed. The EPA has set no federal legal limit for Water Hardness (Calcium/Magnesium). Meeting the legal limit isn't the same as zero risk — test your water to know your level.
How do you remove Water Hardness (Calcium/Magnesium) from water?
Water Hardness (Calcium/Magnesium) is treated by Water Softener and Reverse Osmosis. Choose a system independently certified to NSF/ANSI standards to reduce Water Hardness (Calcium/Magnesium), and test your water first to confirm the level.
Source: EPA MCL / MCLG; WHO guidelines; NSF/ANSI · 2026
Health effects
Hardness is dissolved calcium and magnesium. Not a health hazard, but it causes limescale on fixtures and water heaters, spotting on dishes, reduced soap lather, and can shorten appliance lifespan. Measured in grains per gallon (gpg).
The health-based goal vs. the legal limit
The federal legal limit (MCL) is the maximum allowed by law. The health-based goal (EPA MCLG / WHO) is a health target — it is often stricter than the legal limit, and it is not itself a legal limit.
Health-based goal (EPA MCLG / WHO)
No health-based goal set
Federal legal limit (MCL)
No federal limit set
Source: EPA MCL / MCLG; WHO guidelines · 2026
Not affiliated with or endorsed by EWG.
What removes Water Hardness (Calcium/Magnesium)
Ion exchange
Water Softener
Swaps the calcium and magnesium that cause hard water for sodium — so scale stops forming.
Look for: NSF/ANSI 44 certification
How it works→Semipermeable membrane filtration
Reverse Osmosis
Pushes water through a fine membrane that removes the dissolved solids most filters miss.
Look for: NSF/ANSI 58 certification
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Is Water Hardness (Calcium/Magnesium) in your water?
Check your city's public record, then book a free 30-minute test to confirm what's in your home.