Is St. Louis, MO Tap Water Safe to Drink?
Yes, St. Louis tap water is safe to drink. No contaminants exceed health guidelines. However, St. Louis has hard water at 150 PPM, which will cause scale buildup in plumbing and appliances over time. A softener or conditioner is worth considering.
Hardness Scale: Where St. Louis Falls
0Slightly
60Moderate
120Hard
180Very Hard
250Extreme
400+
How St. Louis Compares
St. Louis's water is 9% harder than the national average of 138 PPM. It ranks #448 out of 1000 cities in our database (harder than 55% of US cities we track). Within Missouri, it ranks #13 of 15 cities (29% below the state average of 211 PPM). Among major US cities (500k+), St. Louis ranks #41 of 100 for hardness. At this hardness level, water heaters run an estimated 28% less efficiently due to scale insulation, and major water-using appliances typically last 2 years less than the national average lifespan.
What St. Louis's Water Means for Your Home
Hardness: 150 PPM - Treatment Recommended
St. Louis's water is hard at 150 PPM (8.8 GPG). That's enough to notice every day: gradual scale on fixtures, spots on dishes, soap that doesn't lather the way it should. That's 29% softer than the Missouri average. Homeowners who install a water softener or salt-free conditioner notice the difference fast: better lathering, cleaner dishes, and appliances that last longer. That adds up. Hard water at 150 PPM increases household costs through scale-coated water heaters that use more energy, extra soap and detergent, and appliances that wear out faster. Most St. Louis homeowners don't realize it until the plumber shows up.
Contaminants & Safety
Disinfection byproducts are the notable finding here. St. Louis's water has TTHMs at 30.9 ppb and HAA5 at 20.7 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
St. Louis's surface water supply requires heavy chlorination to stay safe — but that creates a tradeoff. The treatment process generates disinfection byproducts: TTHMs at 30.9 ppb (39% of the legal limit, but 206x the EWG guideline) and HAA5 at 20.7 ppb (35% of the legal limit, but 207x 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 1.26 ppb, which is 63x 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 150 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) | 150 PPM | < 60 PPM | No federal limit | ⚠ Hard |
| Total Dissolved Solids | 230 PPM | < 300 PPM | 500 PPM | ✓ OK |
| PFAS (total) | 5.05 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 | 1.1 mg/L | Taste threshold ~1.0 | 4.0 mg/L | ✓ Normal |
| Nitrate | 0.459 mg/L | 5 mg/L | 10 mg/L | ✓ OK |
Our Top Picks for St. Louis (150 PPM)
Hard water at 150 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 1.1 mg/L chlorine, many St. Louis 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 St. Louis
With 150 PPM hardness, a quick test strip confirms whether your specific tap matches St. Louis's average before you invest in a softener. Hardness can vary within the same system.
Free option: Request St. Louis Water Division's annual Consumer Confidence Report for official city-level data.
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About St. Louis's Water Supply
Water Utility: St. Louis Water Division
Water Source: Missouri + Mississippi Rivers (Surface Water)
Population Served: 1,111,000
Hardness: 150 PPM (8.8 grains per gallon)
St. Louis's drinking water comes from surface sources — Missouri + Mississippi Rivers. 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 1.1 million residents.
Water quality can vary by neighborhood and season. For your exact numbers, request St. Louis Water Division'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 St. Louis Water Division in St. Louis, MO, including ZIP codes:
62002, 62009, 62010, 62014, 62018, 62021, 62023, 62024, 62025, 62026, 62033, 62034, 62040, 62046, 62048, 62058, 62060, 62062, 62067, 62069, 62071, 62074, 62084, 62085, 62087, 62088, 62090, 62091, 62093, 62095, 62097, 62201, 62202, 62203, 62204, 62205, 62206, 62207, 62234, 62239, 62240, 63101, 63102, 63103, 63104, 63106, 63107, 63108, 63110, 63112, 63113, 63115, 63118, 63120, 63121, 63135, 63136, 63137, 63138, 63140, 63147, 63150, 63155, 63156, 63157, 63158, 63160, 63163, 63164, 63166, 63169, 63171, 63177, 63178, 63179, 63180, 63182, 63188, 63195, 63197, 63199
If your ZIP code is listed above, this report covers your water supply. Water quality may vary slightly by neighborhood.
Water Softener Sizing for St. Louis
At 150 PPM (8.8 GPG), here is how to size a softener for your St. Louis home. Multiply hardness in GPG (8.8) by daily water usage (roughly 50 gallons per person). A family of four uses about 200 gallons/day: 8.8 GPG × 200 gal = 1760 grains/day. Over a 7-day regeneration cycle, that is 12,320 grains - a 32,000-grain softener is the right fit for most St. Louis households.
Compare St. Louis to Other Missouri Cities
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Frequently Asked Questions About St. Louis Water
Is St. Louis tap water safe to drink?
Where does St. Louis's water come from?
Do I need a water softener in St. Louis?
Does St. Louis water damage tankless water heaters?
How much does hard water cost a St. Louis household per year?
What is the hardness of St. Louis water in grains per gallon?
What size water softener do I need for St. Louis?
Salt-based softener or salt-free conditioner for St. Louis?
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 St. Louis Homeowners Actually Buy
Common purchases for homes with 150 PPM water.
Affiliate disclosure: we may earn a commission. Selection based on St. Louis's water data.