Is Gresham, OR Tap Water Safe to Drink?
Yes, Gresham tap water is safe to drink. Hardness is low at 22 PPM, and no contaminants exceed health guidelines. Most homes here don't need treatment.
Hardness Scale: Where Gresham Falls
0Slightly
60Moderate
120Hard
180Very Hard
250Extreme
400+
How Gresham Compares
Gresham'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 Oregon, it ranks #24 of 48 cities (12% below the state average of 25 PPM). Among cities (50k-100k), Gresham ranks #238 of 258 for hardness.
What Gresham's Water Means for Your Home
Hardness: 22 PPM - Low Concern
Gresham'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. Gresham is softer than 89% of US cities. If you're thinking about water treatment, contaminant filtration is where to focus your money, not softening.
Contaminants & Safety
Disinfection byproducts are the notable finding here. Gresham's water has TTHMs at 31.6 ppb and HAA5 at 27.3 ppb — both within legal limits, but the EWG health guidelines are far stricter. These byproducts form when chlorine reacts with organic matter during treatment. A whole-house activated carbon filter reduces both chlorine and its byproducts. Want the full picture? Request your utility's annual Consumer Confidence Report.
What's in the Treatment Process
Gresham's surface water supply requires heavy chlorination to stay safe — but that creates a tradeoff. The treatment process generates disinfection byproducts: TTHMs at 31.6 ppb (40% of the legal limit, but 210x the EWG guideline) and HAA5 at 27.3 ppb (46% of the legal limit, but 273x 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) | 22 PPM | < 60 PPM | No federal limit | ✓ OK |
| Total Dissolved Solids | 33 PPM | < 300 PPM | 500 PPM | ✓ OK |
| PFAS (total) | 0 ppt | — | No total limit | ✓ ND |
| ↳ PFOA | 0 ppt | 0 ppt | 4 ppt (2024) | ✓ OK |
| ↳ PFOS | 0 ppt | 0 ppt | 4 ppt (2024) | ✓ OK |
| Lead | 4.2 ppb | 0 ppb (no safe level) | 15 ppb (10 ppb in 2027) | ✓ Low |
| Chlorine / Chloramine | 0.7 mg/L | Taste threshold ~1.0 | 4.0 mg/L | ✓ Normal |
| Nitrate | Not reported | 5 mg/L | 10 mg/L | N/A |
Good news for Gresham residents. Your water quality is generally good. Most homes in this area do not need a water softener. If you have concerns about lead (especially in buildings constructed before 1986) or chlorine taste, a point-of-use filter is the most practical and cost-effective solution.
How to Test Your Water in Gresham
City-wide data is a solid starting point, but your specific tap might differ based on plumbing age, distance from the treatment plant, or seasonal changes.
Free option: Request City of Gresham's annual Consumer Confidence Report for official city-level data.
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About Gresham's Water Supply
Water Utility: City of Gresham
Water Source: Bull Run Reservoir (Portland system) (Surface Water)
Population Served: 73,932
Hardness: 22 PPM (1.3 grains per gallon)
Gresham's drinking water comes from surface sources — Bull Run Reservoir (Portland 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 74,000 residents.
Water quality can vary by neighborhood and season. For your exact numbers, request City of Gresham'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 City of Gresham in Gresham, OR, including ZIP codes:
97009, 97024, 97030, 97080
If your ZIP code is listed above, this report covers your water supply. Water quality may vary slightly by neighborhood.
Compare Gresham to Other Oregon Cities
Frequently Asked Questions About Gresham Water
Is Gresham tap water safe to drink?
Where does Gresham's water come from?
Do I need a water softener in Gresham?
What are disinfection byproducts in Gresham's water?
Can I drink Gresham tap water straight from the faucet?
What water filter is best for Gresham?
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.