St. Louis, MO Tap Water Quality Report (2026): Grade C
City of St. Louis Department of Watershed Management
How St. Louis’s Water Impacts Drinking, Skin & Appliances
PFAS (3.9 ppt) & Lead (5.6 ppb)
St. Louis tap water earns a C grade thanks to naturally soft Chattahoochee River water (150 mg/L / 8.8 gpg), though chlorine disinfection byproducts (48.2 ppb TTHMs) and 3.9 ppt trace PFAS near the 4.0 ppt EPA limit warrant under-sink carbon or RO filtration. Boiling tap water concentrates PFAS and lead rather than removing them. Installing an NSF/ANSI 58 tankless reverse osmosis system under your kitchen sink reduces >98% of PFOA/PFOS, lead, chromium-6, and 93.59% of dissolved solids right at the tap.
Fix Kitchen Tap: Waterdrop G3P800 →8.8 gpg (150 mg/L) Soft Water
At 8.8 grains per gallon, calcium and magnesium carbonate crust inside tank and tankless water heaters, cutting heating efficiency by up to 24% and leaving white chalky spots on glass shower doors and faucets.
Fix Scale: SpringWell Whole-House →Chlorine & 48.2 ppb TTHMs
City of St. Louis Department of Watershed Management uses free chlorine to disinfect distribution mains, producing 48.2 ppb Total Trihalomethanes (TTHMs) and 29.8 ppb Haloacetic Acids that volatilize in hot showers and dry out sensitive skin.
Compare Aquasana Rhino EQ-1000 →Free 6-Month Replacement Filter Reminder
Saturated carbon pre-filters allow PFAS and chlorine breakthrough after 6 months (causing membrane fouling). Pick your system below and we will email your exact OEM cartridge match when it is time to swap.
Why Tankless RO Beats Bottled Water & Pitchers
$7,300 over 5 years plus 240,000 nanoplastics per liter.
NSF-42 carbon filters chlorine taste only, missing hard minerals.
G3P800 filter cost (~$160/yr); certified >98% PFOA/PFOS & 93.6% TDS reduction.
Claim the Exclusive City Water Specialist Slot ($149/mo)
Are you a state-licensed C-36 / Master Plumber or WQA-certified water treatment installer? Lock in the single Featured Local Installer spot on your city's tap water report page for $149/month flat—zero per-lead bidding wars.
Frequently Asked Questions
Is St. Louis, MO tap water safe to drink in 2026?
St. Louis tap water earns a C grade on CleanWaterGrade. While it meets baseline utility standards, testing shows 3.9 ppt combined PFOA/PFOS (vs the 4.0 ppt EPA limit), 5.6 ppb 90th-percentile lead, and 8.8 gpg (150 mg/L) hardness.
How hard is the water in St. Louis, MO?
St. Louis water hardness averages 8.8 grains per gallon (150 mg/L), classified by the USGS as Hard.
What is the best water filter for St. Louis, MO?
For drinking and cooking in St. Louis, an NSF-58 under-sink reverse osmosis system like the Waterdrop G3P800 reduces >98% of PFOA/PFOS, lead, and 93.59% of TDS. For whole-home scale and disinfectant protection, the Aquasana Rhino EQ-1000 is matched to St. Louis water chemistry.