Contaminant · Water
Hard Water (Hardness)
What it is
Hard water is water high in dissolved calcium and magnesium, picked up as water moves through limestone and mineral deposits. It causes scale on fixtures and appliances, spotting on dishes, and reduced soap lather.
Why it matters
Hardness is an aesthetic and scale concern, not a health-based contaminant - the EPA does not set a health limit for it. We are explicit about this because it is widely misunderstood: hard water is a nuisance and maintenance issue, not a safety one.
What removes it
A water softener (ion exchange) or a salt-free conditioner - not a point-of-use drinking-water filter. No drinking-water filter is certified to 'remove' hardness, and softeners sit outside what we score. We say so plainly rather than point you at a filter that will not help.
Reference: EPA Secondary (non-health) standards; USGS water-hardness mapping.
Scored filters certified for Hard Water (Hardness)
No filter in our scored set currently holds a verifiable certification for Hard Water (Hardness). We will list one here only when its certification is confirmed on the official database - we do not list "tested to" claims.
FAQ
- Which filter removes hard water?
- None of the drinking-water filters we score address hardness. Softening is a whole-house water softener's job, which is a different product category we do not currently score. A carbon or RO drinking filter will not fix scale.
- Is hard water bad for you?
- Hardness is regulated as an aesthetic concern, not a health one. The issue is scale, spotting, and soap performance, not safety.