Because Fluoride is associated with health effects at sustained elevated exposures, residents in Castle Rock, Colorado may find it useful that local water systems have returned detectable concentrations — facts that bear on long-term household water decisions.

Data: EPA SDWIS, CCR Reports, ECHO Last verified: 2026-04-05

Fluoride in Castle Rock Tap Water

Fluoride has been detected in Castle Rock, Colorado drinking water at a maximum level of 8 ppb — below the EPA MCL of 4.0 mg/L (MCL) / 2.0 mg/L (SMCL).

This analysis covers 99,741 residents across 3 ZIP codes in Castle Rock.

Castle Rock's overall water quality grade is C (68/100).

Is Fluoride in Castle Rock Water Safe?

If you live in an affected ZIP code, consider installing a reverse osmosis or activated alumina filter certified under NSF 58 and testing your water independently.

Fluoride Levels by ZIP Code

Average fluoride level across Castle Rock: 8 ppb

Health Effects of Fluoride

• Skeletal fluorosis at levels above 4 mg/L (bone pain, joint stiffness)
• Dental fluorosis in children at levels above 2 mg/L
• At 0.7 mg/L (water fluoridation level), helps prevent tooth decay
• Possible thyroid effects at high chronic exposure

Health risk severity: Moderate. Governed by the National Primary Drinking Water Regulations.

How Fluoride Gets Into Drinking Water

• Intentional water fluoridation (0.7 mg/L target, beneficial)
• Natural deposits in certain rock formations
• Industrial discharge (aluminum, fertilizer production)
• Naturally elevated in some groundwater (especially arid regions)

What to Do About Fluoride in Castle Rock Water

1. Reverse osmosis removes 90%+ of fluoride
2. Activated alumina filters are effective for fluoride
3. Bone char carbon can reduce fluoride
4. Standard activated carbon filters do NOT remove fluoride

Look for filters certified under NSF 58 for fluoride removal.

Related

• Fluoride — National Overview
• Colorado Water Quality
• Castle Rock Water Quality
• Check Your ZIP Code