Is Greenwich, CT Tap Water Safe to Drink?
Greenwich tap water is legally compliant, but one contaminant exceeds health guidelines. Specifically: PFAS above EPA limits (PFOA: 7.73 ppt, PFOS: 6.25 ppt — limit is 4 ppt each). A point-of-use filter is recommended for drinking and cooking water.
Hardness Scale: Where Greenwich Falls
0Slightly
60Moderate
120Hard
180Very Hard
250Extreme
400+
How Greenwich Compares
Greenwich's water is 84% softer than the national average of 138 PPM - ranking in the bottom 90% for hardness nationwide. Most homes here do not need a softener. Within Connecticut, it ranks #9 of 13 cities (29% below the state average of 31 PPM). Among large cities (200k-500k), Greenwich ranks #154 of 165 for hardness.
What Greenwich's Water Means for Your Home
Hardness: 22 PPM - Low Concern
Greenwich's water is slightly hard at 22 PPM. Most households won't notice any issues at this level. Scale buildup is minimal, and a water softener would be overkill. Greenwich is softer than 90% of US cities. If you're thinking about water treatment, contaminant filtration is where to focus your money, not softening.
Contaminants & Safety
Forever chemicals (PFAS) are worth watching here. Greenwich has PFOA at 7.73 ppt and PFOS at 6.25 ppt, exceeding the EPA's 2024 limit of 4 ppt per compound. PFAS are synthetic compounds that accumulate in your body over time. A certified carbon filter or reverse osmosis system with NSF P473 certification is the most effective protection. See the regulatory timeline.
What's in the Treatment Process
Greenwich's surface water supply requires heavy chlorination to stay safe — but that creates a tradeoff. The treatment process generates disinfection byproducts: TTHMs at 52.4 ppb (66% of the legal limit, but 349x the EWG guideline) and HAA5 at 31.9 ppb (53% of the legal limit, but 319x 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.
Chromium-6 was detected at 0.0506 ppb, which is 2.5x the EWG health guideline. There's no separate federal limit for chromium-6, only total chromium. A reverse osmosis system is the most effective removal method. 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) | 22 PPM | < 60 PPM | No federal limit | ✓ OK |
| Total Dissolved Solids | 35 PPM | < 300 PPM | 500 PPM | ✓ OK |
| PFAS (total) | 39.75 ppt | — | No total limit | Detected |
| ↳ PFOA | 7.73 ppt | 0 ppt | 4 ppt (2024) | ⚠ Exceeds |
| ↳ PFOS | 6.25 ppt | 0 ppt | 4 ppt (2024) | ⚠ Exceeds |
| Lead | 1.7 ppb | 0 ppb (no safe level) | 15 ppb (10 ppb in 2027) | ✓ Low |
| Chlorine / Chloramine | 0.5 mg/L | Taste threshold ~1.0 | 4.0 mg/L | ✓ Normal |
| Nitrate | 0.765 mg/L | 5 mg/L | 10 mg/L | ✓ OK |
Recommended Filter for Greenwich
PFAS exceed EPA limits (PFOA: 7.73 ppt, PFOS: 6.25 ppt — limit: 4 ppt each). A certified filter reduces these contaminants effectively.
How to Test Your Water in Greenwich
With PFAS at 39.75 ppt in Greenwich's supply, confirming your home's specific levels is especially important. PFAS vary by neighborhood and can concentrate differently depending on your position in the distribution system.
Free option: Request Aquarion Water Company's annual Consumer Confidence Report for official city-level data.
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About Greenwich's Water Supply
Water Utility: Aquarion Water Company
Water Source: Putnam Lake & Kensico system (Surface Water)
Population Served: 351,756
Hardness: 22 PPM (1.3 grains per gallon)
Greenwich's drinking water comes from surface sources — Putnam Lake & Kensico system. 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 352,000 residents.
Water quality can vary by neighborhood and season. For your exact numbers, request Aquarion Water Company'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 Aquarion Water Company in Greenwich, CT, including ZIP codes:
06807, 06830, 06831, 06836, 06878, 10504, 10506, 10507, 10573
If your ZIP code is listed above, this report covers your water supply. Water quality may vary slightly by neighborhood.
Compare Greenwich to Other Connecticut Cities
Frequently Asked Questions About Greenwich Water
Is Greenwich tap water safe to drink?
Where does Greenwich's water come from?
Do I need a water softener in Greenwich?
How do I remove PFAS from Greenwich tap water?
What water filter is best for Greenwich?
Is Greenwich water safe for babies and infants?
What are disinfection byproducts in Greenwich's water?
Is chromium-6 in Greenwich's water?
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 Greenwich Homeowners Actually Buy
Prioritized for contaminant reduction for homes with 22 PPM water and PFAS above EPA limits.
Affiliate disclosure: we may earn a commission. Selection based on Greenwich's water data.