Is Delaware, OH Tap Water Safe to Drink?
Yes, Delaware tap water is safe to drink. No contaminants exceed health guidelines. However, Delaware has very hard water at 320 PPM, which will cause scale buildup in plumbing and appliances over time. A water softener is worth considering.
Hardness Scale: Where Delaware Falls
0Slightly
60Moderate
120Hard
180Very Hard
250Extreme
400+
How Delaware Compares
Delaware's water is 132% harder than the national average of 138 PPM. It ranks #13 out of 1000 cities in our database (harder than 99% of US cities we track). Within Ohio, Delaware has the 3rd hardest water out of 34 cities - 46% above the state average of 219 PPM. Among smaller cities, Delaware ranks #10 of 288 for hardness. At this hardness level, water heaters run an estimated 59% less efficiently due to scale insulation, and major water-using appliances typically last 4 years less than the national average lifespan.
What Delaware's Water Means for Your Home
Hardness: 320 PPM - Treatment Recommended
Delaware has some exceptionally hard water. At 320 PPM (18.7 grains per gallon), your tap is loaded with mineral content carried in from the watershed geology. Here's the thing: it's perfectly safe to drink. The minerals won't hurt you. But they will hurt your wallet. That adds up. Hard water at 320 PPM increases household costs through scale-coated water heaters that use more energy, extra soap and detergent, and appliances that wear out faster. Most Delaware homeowners don't realize it until the plumber shows up. That's 46% harder than the Ohio average.
Contaminants & Safety
Disinfection byproducts are the notable finding here. Delaware's water has TTHMs at 20.1 ppb and HAA5 at 7.23 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
Delaware's surface water supply requires heavy chlorination to stay safe — but that creates a tradeoff. The treatment process generates disinfection byproducts: TTHMs at 20.1 ppb (25% of the legal limit, but 134x the EWG guideline) and HAA5 at 7.23 ppb (12% of the legal limit, but 72x 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 0.273 ppb, which is 14x 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.
How Hard Water Affects Your Home
At 320 PPM, untreated hard water has measurable effects on household costs and appliance life:
- Water heater inefficiency: Scale insulation forces the heater to work harder (DOE estimates up to 22% more energy for heavily scaled units)
- Soap and detergent: Hard water reduces lathering, requiring significantly more product
- Appliance replacement: Water heaters, dishwashers, and washing machines fail 2-4 years earlier due to scale buildup
- Plumbing maintenance: Scale buildup in pipes reduces flow and requires more frequent service
Note: Impact varies by household size, water usage, and local energy costs. A home water test provides the most accurate assessment for your specific situation.
| Contaminant | Detected | Health Guideline | Legal Limit | Status |
|---|---|---|---|---|
| Hardness (as CaCO₃) | 320 PPM | < 60 PPM | No federal limit | ⚠ Very Hard |
| Total Dissolved Solids | 480 PPM | < 300 PPM | 500 PPM | ⚠ Elevated |
| 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 | 1 ppb | 0 ppb (no safe level) | 15 ppb (10 ppb in 2027) | ✓ Low |
| Chlorine / Chloramine | 1.2 mg/L | Taste threshold ~1.0 | 4.0 mg/L | ✓ Normal |
| Nitrate | 1.09 mg/L | 5 mg/L | 10 mg/L | ✓ OK |
Our Top Picks for Delaware (320 PPM)
Hard water at 320 PPM causes scale buildup, increased energy use, and premature appliance failure. A softener protects your plumbing and appliances.
Quick Fix for Chlorine: Shower Filter
At 1.2 mg/L chlorine, many Delaware 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 Delaware
With 320 PPM hardness, a quick test strip confirms whether your specific tap matches Delaware's average before you invest in a softener. Hardness can vary within the same system.
Free option: Request City of Delaware Water'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 Delaware's Water Supply
Water Utility: City of Delaware Water
Water Source: Olentangy River + wells (Surface Water)
Population Served: 43,895
Hardness: 320 PPM (18.7 grains per gallon)
Delaware's drinking water comes from surface sources — Olentangy River + 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. Despite the treatment process, mineral hardness from the watershed carries through. The system serves 44,000 residents.
Water quality can vary by neighborhood and season. For your exact numbers, request City of Delaware Water'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 Delaware Water in Delaware, OH, including ZIP codes:
43003, 43007, 43015, 43032, 43036, 43040, 43041, 43045, 43061, 43066, 43067, 43077, 43301, 43302, 43314, 43315, 43319, 43320, 43321, 43322, 43332, 43334, 43336, 43337, 43340, 43341, 43342, 43344, 43345, 43347, 43350, 43356, 43358
If your ZIP code is listed above, this report covers your water supply. Water quality may vary slightly by neighborhood.
Water Softener Sizing for Delaware
At 320 PPM (18.7 GPG), here is how to size a softener for your Delaware home. Multiply hardness in GPG (18.7) by daily water usage (roughly 50 gallons per person). A family of four uses about 200 gallons/day: 18.7 GPG × 200 gal = 3740 grains/day. Over a 7-day regeneration cycle, that is 26,180 grains - a 32,000-grain softener is the right fit for most Delaware households.
Compare Delaware to Other Ohio Cities
Frequently Asked Questions About Delaware Water
Is Delaware tap water safe to drink?
Where does Delaware's water come from?
Do I need a water softener in Delaware?
Does Delaware water damage tankless water heaters?
How much does hard water cost a Delaware household per year?
What is the hardness of Delaware water in grains per gallon?
What size water softener do I need for Delaware?
Salt-based softener or salt-free conditioner for Delaware?
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 Delaware Homeowners Actually Buy
Common purchases for homes with 320 PPM water.
Affiliate disclosure: we may earn a commission. Selection based on Delaware's water data.