Is Centennial, CO Tap Water Safe to Drink?
Yes, Centennial tap water is safe to drink. Hardness is low at 75 PPM, and no contaminants exceed health guidelines. Most homes here don't need treatment.
Hardness Scale: Where Centennial Falls
0Slightly
60Moderate
120Hard
180Very Hard
250Extreme
400+
How Centennial Compares
Centennial's water is 46% softer than the national average of 138 PPM - ranking in the bottom 62% for hardness nationwide. Most homes here do not need a softener. Within Colorado, it ranks #14 of 23 cities (24% below the state average of 99 PPM). Among cities (50k-100k), Centennial ranks #175 of 258 for hardness.
What Centennial's Water Means for Your Home
Hardness: 75 PPM - Low Concern
Centennial's water is moderately hard at 75 PPM. You'll see some spotting on glassware and a film on shower doors over time, but it's not the kind of hardness that demands a full softener. A salt-free conditioner is worth considering if you have a tankless water heater or high-end fixtures.
Contaminants & Safety
Lead levels deserve attention. At 9 ppb, Centennial is above the ideal of zero, though below the EPA action level of 15 ppb (dropping to 10 ppb in November 2027 under the Lead and Copper Rule Improvements). The lead typically comes from aging service lines or interior plumbing, not the treatment plant. A point-of-use filter certified for lead at the kitchen faucet is a practical safeguard, especially in older homes.
What's in the Treatment Process
Centennial's surface water supply requires heavy chlorination to stay safe — but that creates a tradeoff. The treatment process generates disinfection byproducts: TTHMs at 28.9 ppb (36% of the legal limit, but 192x the EWG guideline) and HAA5 at 16.6 ppb (28% of the legal limit, but 166x the EWG guideline). These are within legal limits, but the EWG sets much tighter thresholds based on cancer-risk research. A whole-house activated carbon filter reduces both chlorine and byproducts. All measurements are within federal legal limits. The EWG guidelines represent a more conservative, health-based standard.
| Contaminant | Detected | Health Guideline | Legal Limit | Status |
|---|---|---|---|---|
| Hardness (as CaCO₃) | 75 PPM | < 60 PPM | No federal limit | ✓ OK |
| Total Dissolved Solids | 104 PPM | < 300 PPM | 500 PPM | ✓ OK |
| PFAS (total) | Not tested | — | No total limit | N/A |
| Lead | 9 ppb | 0 ppb (no safe level) | 15 ppb (10 ppb in 2027) | ⚠ Elevated |
| Chlorine / Chloramine | 0.6 mg/L | Taste threshold ~1.0 | 4.0 mg/L | ✓ Normal |
| Nitrate | 0.0578 mg/L | 5 mg/L | 10 mg/L | ✓ OK |
Recommendations for Centennial Homes
How to Test Your Water in Centennial
Lead enters water from your home's plumbing, not the treatment plant — so Centennial's city-wide average of 9 ppb may not match your tap. Testing your specific faucet is the only way to know. Run cold water for 30 seconds before collecting a sample.
Free option: Request Centennial Water & Sanitation's annual Consumer Confidence Report for official city-level data.
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About Centennial's Water Supply
Water Utility: Centennial Water & Sanitation
Water Source: South Platte River & Cherry Creek (Surface Water)
Population Served: 55,000
Hardness: 75 PPM (4.4 grains per gallon)
Centennial's drinking water comes from surface sources — South Platte River & Cherry Creek. Surface water requires more extensive treatment than groundwater, including coagulation, filtration, and disinfection. This heavier chlorination is why disinfection byproducts tend to be higher in surface-supplied systems. On the upside, surface sources often deliver softer water than deep aquifers. The system serves 55,000 residents.
Water quality can vary by neighborhood and season. For your exact numbers, request Centennial Water & Sanitation's Consumer Confidence Report (CCR) or test your own tap.
ZIP Codes Covered by This Report
This water quality data applies to all areas served by Centennial Water & Sanitation in Centennial, CO, including ZIP codes:
80111, 80112, 80113, 80120, 80121, 80122, 80124, 80125, 80126, 80129, 80130, 80150, 80151, 80155, 80160, 80161, 80165, 80166
If your ZIP code is listed above, this report covers your water supply. Water quality may vary slightly by neighborhood.
Compare Centennial to Other Colorado Cities
Frequently Asked Questions About Centennial Water
Is Centennial tap water safe to drink?
Where does Centennial's water come from?
Do I need a water softener in Centennial?
What water filter is best for Centennial?
What is the hardness of Centennial water in grains per gallon?
Is Centennial water safe for babies and infants?
What are disinfection byproducts in Centennial's water?
Can I drink Centennial tap water straight from the faucet?
Data sources: Lead and copper data from EPA Safe Drinking Water Act LCR reporting. Contaminant data from utility-reported testing results. PFAS data from EPA UCMR5 (2023–2025). Hardness from USGS and municipal reports. Data reflects system-level testing results and may not match your specific tap due to neighborhood plumbing, season, or recent utility changes. For your utility's latest results, request their Consumer Confidence Report (CCR). Our methodology. Last updated: 2026-02-24.
What Centennial Homeowners Actually Buy
Common purchases for homes with 75 PPM water.
Affiliate disclosure: we may earn a commission. Selection based on Centennial's water data.