Is O'Fallon, MO Tap Water Safe to Drink?
Yes, O'Fallon tap water is safe to drink. No contaminants exceed health guidelines. However, O'Fallon has very hard water at 200 PPM, which will cause scale buildup in plumbing and appliances over time. A water softener is worth considering.
Hardness Scale: Where O'Fallon Falls
0Slightly
60Moderate
120Hard
180Very Hard
250Extreme
400+
How O'Fallon Compares
O'Fallon's water is 45% harder than the national average of 138 PPM. It ranks #314 out of 1000 cities in our database (harder than 69% of US cities we track). Within Missouri, it ranks #8 of 15 cities (5% below the state average of 211 PPM). Among smaller cities, O'Fallon ranks #70 of 288 for hardness. At this hardness level, water heaters run an estimated 37% less efficiently due to scale insulation, and major water-using appliances typically last 3 years less than the national average lifespan.
What O'Fallon's Water Means for Your Home
Hardness: 200 PPM - Treatment Recommended
O'Fallon has some seriously hard water. At 200 PPM (11.7 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 200 PPM increases household costs through scale-coated water heaters that use more energy, extra soap and detergent, and appliances that wear out faster. Most O'Fallon homeowners don't realize it until the plumber shows up. That's 5% softer than the Missouri average.
Contaminants & Safety
Disinfection byproducts are the notable finding here. O'Fallon's water has TTHMs at 7.17 ppb and HAA5 at 3.58 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.
How Hard Water Affects Your Home
At 200 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) | 200 PPM | < 60 PPM | No federal limit | ⚠ Very Hard |
| Total Dissolved Solids | 337 PPM | < 300 PPM | 500 PPM | ⚠ Elevated |
| PFAS (total) | 9.5 ppt | — | No total limit | Detected |
| ↳ PFOA | 0 ppt | 0 ppt | 4 ppt (2024) | ✓ OK |
| ↳ PFOS | 0 ppt | 0 ppt | 4 ppt (2024) | ✓ OK |
| Lead | 1.5 ppb | 0 ppb (no safe level) | 15 ppb (10 ppb in 2027) | ✓ Low |
| Chlorine / Chloramine | 0.3 mg/L | Taste threshold ~1.0 | 4.0 mg/L | ✓ Normal |
| Nitrate | 0.0812 mg/L | 5 mg/L | 10 mg/L | ✓ OK |
Our Top Picks for O'Fallon (200 PPM)
Hard water at 200 PPM causes scale buildup, increased energy use, and premature appliance failure. A softener protects your plumbing and appliances.
How to Test Your Water in O'Fallon
With 200 PPM hardness, a quick test strip confirms whether your specific tap matches O'Fallon's average before you invest in a softener. Hardness can vary within the same system.
Free option: Request City of O'Fallon Water's annual Consumer Confidence Report for official city-level data.
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About O'Fallon's Water Supply
Water Utility: City of O'Fallon Water
Water Source: Missouri River & wells (Surface Water)
Population Served: 32,515
Hardness: 200 PPM (11.7 grains per gallon)
O'Fallon's drinking water comes from surface sources — Missouri 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 33,000 residents.
Water quality can vary by neighborhood and season. For your exact numbers, request City of O'Fallon 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 O'Fallon Water in O'Fallon, MO, including ZIP codes:
62006, 62045, 62047, 62053, 62065, 62070, 62301, 62305, 62312, 62314, 62338, 62343, 62345, 62347, 62352, 62355, 62356, 62357, 62360, 62361, 62363, 62365, 62366, 62370, 62376, 63013, 63014, 63037, 63056, 63068, 63090, 63330, 63332, 63333, 63334, 63336, 63338, 63339, 63341, 63342, 63343, 63344, 63347, 63348, 63349, 63350, 63351, 63353, 63357, 63359, 63361, 63362, 63363, 63365, 63366, 63367, 63368, 63369, 63370, 63377, 63378, 63379, 63380, 63381, 63383, 63385, 63387, 63389, 63390, 63401, 63433, 63441, 63459, 63467
If your ZIP code is listed above, this report covers your water supply. Water quality may vary slightly by neighborhood.
Water Softener Sizing for O'Fallon
At 200 PPM (11.7 GPG), here is how to size a softener for your O'Fallon home. Multiply hardness in GPG (11.7) by daily water usage (roughly 50 gallons per person). A family of four uses about 200 gallons/day: 11.7 GPG × 200 gal = 2340 grains/day. Over a 7-day regeneration cycle, that is 16,380 grains - a 32,000-grain softener is the right fit for most O'Fallon households.
Compare O'Fallon to Other Missouri Cities
Frequently Asked Questions About O'Fallon Water
Is O'Fallon tap water safe to drink?
Where does O'Fallon's water come from?
Do I need a water softener in O'Fallon?
Does O'Fallon water damage tankless water heaters?
How much does hard water cost a O'Fallon household per year?
What is the hardness of O'Fallon water in grains per gallon?
What size water softener do I need for O'Fallon?
Salt-based softener or salt-free conditioner for O'Fallon?
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 O'Fallon Homeowners Actually Buy
Common purchases for homes with 200 PPM water.
Affiliate disclosure: we may earn a commission. Selection based on O'Fallon's water data.