Is Federal Way, WA Tap Water Safe to Drink?
Federal Way tap water is legally compliant, but one contaminant exceeds health guidelines. Specifically: PFAS above EPA limits (PFOS: 4.1 ppt — limit is 4 ppt each). A point-of-use filter is recommended for drinking and cooking water.
Hardness Scale: Where Federal Way Falls
0Slightly
60Moderate
120Hard
180Very Hard
250Extreme
400+
How Federal Way Compares
Federal Way's water is 87% softer than the national average of 138 PPM - ranking in the bottom 94% for hardness nationwide. Most homes here do not need a softener. Within Washington, it ranks #17 of 26 cities (45% below the state average of 33 PPM). Among mid-size cities (100k-200k), Federal Way ranks #175 of 189 for hardness.
What Federal Way's Water Means for Your Home
Hardness: 18 PPM - Low Concern
Federal Way's water is slightly hard at 18 PPM. Most households won't notice any issues at this level. Scale buildup is minimal, and a water softener would be overkill. Federal Way is softer than 94% 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. Federal Way has PFOS at 4.1 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
Federal Way's surface water supply requires heavy chlorination to stay safe — but that creates a tradeoff. The treatment process generates disinfection byproducts: TTHMs at 14.4 ppb (18% of the legal limit, but 96x the EWG guideline) and HAA5 at 8.35 ppb (14% of the legal limit, but 83x 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 0.0845 ppb, which is 4.2x 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) | 18 PPM | < 60 PPM | No federal limit | ✓ OK |
| Total Dissolved Solids | 48 PPM | < 300 PPM | 500 PPM | ✓ OK |
| PFAS (total) | 37.7 ppt | — | No total limit | Detected |
| ↳ PFOA | 0 ppt | 0 ppt | 4 ppt (2024) | ✓ OK |
| ↳ PFOS | 4.1 ppt | 0 ppt | 4 ppt (2024) | ⚠ Exceeds |
| Lead | 1.1 ppb | 0 ppb (no safe level) | 15 ppb (10 ppb in 2027) | ✓ Low |
| Chlorine / Chloramine | 0.9 mg/L | Taste threshold ~1.0 | 4.0 mg/L | ✓ Normal |
| Nitrate | 0.645 mg/L | 5 mg/L | 10 mg/L | ✓ OK |
Recommended Filter for Federal Way
PFAS exceed EPA limits (PFOS: 4.1 ppt — limit: 4 ppt each). A certified filter reduces these contaminants effectively.
How to Test Your Water in Federal Way
With PFAS at 37.7 ppt in Federal Way'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 Lakehaven Water District's annual Consumer Confidence Report for official city-level data.
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About Federal Way's Water Supply
Water Utility: Lakehaven Water District
Water Source: Tacoma Water (Green River), Lakehaven Wells (Surface Water)
Population Served: 118,273
Hardness: 18 PPM (1.1 grains per gallon)
Federal Way's drinking water comes from surface sources — Tacoma Water (Green River), Lakehaven Wells. 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 118,000 residents.
Water quality can vary by neighborhood and season. For your exact numbers, request Lakehaven Water District'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 Lakehaven Water District in Federal Way, WA, including ZIP codes:
98003, 98023, 98063, 98093
If your ZIP code is listed above, this report covers your water supply. Water quality may vary slightly by neighborhood.
Compare Federal Way to Other Washington Cities
Frequently Asked Questions About Federal Way Water
Is Federal Way tap water safe to drink?
Where does Federal Way's water come from?
Do I need a water softener in Federal Way?
How do I remove PFAS from Federal Way tap water?
What water filter is best for Federal Way?
Is Federal Way water safe for babies and infants?
What are disinfection byproducts in Federal Way's water?
Is chromium-6 in Federal Way'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 Federal Way Homeowners Actually Buy
Prioritized for contaminant reduction for homes with 18 PPM water and PFAS above EPA limits.
Affiliate disclosure: we may earn a commission. Selection based on Federal Way's water data.