Is Honolulu, HI Tap Water Safe to Drink?
Yes, Honolulu tap water is safe to drink. Hardness is low at 80 PPM, and no contaminants exceed health guidelines. Most homes here don't need treatment.
Hardness Scale: Where Honolulu Falls
0Slightly
60Moderate
120Hard
180Very Hard
250Extreme
400+
How Honolulu Compares
Honolulu's water is 42% softer than the national average of 138 PPM - ranking in the bottom 60% for hardness nationwide. Most homes here do not need a softener. Within Hawaii, Honolulu has the hardest water out of 7 cities - 51% above the state average of 53 PPM. Among major US cities (500k+), Honolulu ranks #69 of 100 for hardness.
What Honolulu's Water Means for Your Home
Hardness: 80 PPM - Low Concern
Honolulu's water is moderately hard at 80 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. The minerals come from the local aquifer geology. A salt-free conditioner is worth considering if you have a tankless water heater or high-end fixtures.
Contaminants & Safety
Disinfection byproducts are the notable finding here. Honolulu's water has TTHMs at 3.76 ppb and HAA5 at 0.242 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
Chromium-6 is naturally present in Honolulu's aquifer geology at 1.78 ppb — 89x the EWG health guideline. There's no federal legal limit for chromium-6 specifically (only total chromium), which is why EWG tracks it separately. 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) | 80 PPM | < 60 PPM | No federal limit | ✓ OK |
| Total Dissolved Solids | 140 PPM | < 300 PPM | 500 PPM | ✓ OK |
| PFAS (total) | 3 ppt | — | No total limit | Detected |
| ↳ PFOA | 0 ppt | 0 ppt | 4 ppt (2024) | ✓ OK |
| ↳ PFOS | 0 ppt | 0 ppt | 4 ppt (2024) | ✓ OK |
| Lead | 1 ppb | 0 ppb (no safe level) | 15 ppb (10 ppb in 2027) | ✓ Low |
| Chlorine / Chloramine | 1.3 mg/L | Taste threshold ~1.0 | 4.0 mg/L | ✓ Normal |
| Nitrate | 0.41 mg/L | 5 mg/L | 10 mg/L | ✓ OK |
Recommendations for Honolulu Homes
Quick Fix for Chlorine: Shower Filter
At 1.3 mg/L chlorine, many Honolulu residents notice dry skin, brittle hair, and that "pool smell" in the shower. A shower filter installs in 5 minutes, no tools needed.
How to Test Your Water in Honolulu
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 BWS Honolulu's annual Consumer Confidence Report for official city-level data.
📊 Already Tested Your Water?
City averages miss neighborhood-level variation. Share your results to help your neighbors get better data.
We review every submission before publishing. Your ZIP is shown; your identity is not.
About Honolulu's Water Supply
Water Utility: BWS Honolulu
Water Source: Groundwater (basalt aquifer) (Groundwater)
Population Served: 631,389
Hardness: 80 PPM (4.7 grains per gallon)
Honolulu draws its drinking water from groundwater sources — Groundwater (basalt aquifer). Groundwater typically requires less treatment than surface water because the earth acts as a natural filter. The tradeoff: dissolved minerals from underground rock formations, which is why mineral content varies by aquifer depth and geology. The geological profile determines hardness, iron, and trace mineral levels. The system serves 631,000 residents.
Water quality can vary by neighborhood and season. For your exact numbers, request BWS Honolulu'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 BWS Honolulu in Honolulu, HI, including ZIP codes:
96801, 96802, 96803, 96804, 96805, 96806, 96807, 96808, 96809, 96810, 96811, 96812, 96813, 96814, 96815, 96816, 96817, 96818, 96819, 96820, 96821, 96822, 96823, 96824, 96825, 96826, 96828, 96830, 96836, 96837, 96838, 96839, 96840, 96841, 96843, 96844, 96846, 96847, 96848, 96849, 96850, 96858
If your ZIP code is listed above, this report covers your water supply. Water quality may vary slightly by neighborhood.
Compare Honolulu to Other Hawaii Cities
Frequently Asked Questions About Honolulu Water
Is Honolulu tap water safe to drink?
Where does Honolulu's water come from?
Do I need a water softener in Honolulu?
What is the hardness of Honolulu water in grains per gallon?
What are disinfection byproducts in Honolulu's water?
Is chromium-6 in Honolulu's water?
Why does Honolulu water taste like chlorine?
Can I drink Honolulu 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 Honolulu Homeowners Actually Buy
Common purchases for homes with 80 PPM water.
Affiliate disclosure: we may earn a commission. Selection based on Honolulu's water data.