St Louis City, Missouri: drinking water report. St. Louis City operates as an independent city separate from St.
St. Louis City operates as an independent city separate from St. Louis County, drawing its municipal water primarily from the Mississippi and Missouri Rivers through the City of St. Louis Water Division. The system serves roughly 300,000 residents across neighborhoods from Downtown and the Central West End to South City and North St. Louis, with additional wholesale customers in surrounding counties. This aging infrastructure dates to the 1800s in some areas, presenting ongoing challenges for lead service line replacement and treatment plant upgrades.
St. Louis has confronted significant lead contamination issues tied to its extensive legacy of lead service lines, with estimates suggesting over 60,000 such lines remain in use citywide. The city exceeded EPA action levels for lead in 2016 and 2019, triggering mandatory public notifications and accelerated replacement programs. Unlike copper piping issues that typically stem from corrosion in individual buildings, St. Louis faces a systemic problem where lead pipes connecting water mains to homes leach the metal directly into drinking water, particularly in older neighborhoods north of Highway 40 and throughout South City.
Surface water treatment from the Mississippi River also requires vigilance for agricultural runoff contaminants. Missouri River watersheds carry nitrates from fertilizer application and sediment from upstream farming operations, though the city's treatment plants generally manage these within federal limits. More concerning are emerging contaminants under EPA's UCMR5 monitoring program. Missouri utilities have detected PFAS compounds (the "forever chemicals" used in firefighting foam and industrial processes) in multiple systems statewide, though St. Louis Water Division has not reported levels exceeding proposed federal limits. The Mississippi River corridor's industrial history means residents should expect ongoing monitoring for both legacy pollutants like PCBs and newer compounds still being characterized.
Disinfection byproducts present another consideration for St. Louis residents. The chlorine treatment necessary to kill pathogens in surface water reacts with organic matter in the rivers, creating trihalomethanes and haloacetic acids. While the city typically maintains levels below maximum contaminant limits, neighborhoods at the far ends of the distribution system sometimes see higher concentrations as water ages in pipes. Combined with the lead concerns, this creates a situation where filtration becomes particularly important for vulnerable populations including pregnant women, infants, and anyone with compromised immune systems.
Given the documented lead service line challenges and the surface water treatment realities, residents in pre-1950s housing should strongly consider point-of-use filtration certified for lead removal, while anyone concerned about PFAS or disinfection byproducts may want broader spectrum carbon or reverse osmosis systems. Check your water for the most current contamination data in your ZIP code, review our water filter guide for technology comparisons suited to St. Louis conditions, request your detailed report showing specific contaminant levels, or visit the Missouri state page for regulatory context and statewide trends.
Drinking water is one exposure route. These federal datasets also cover St Louis City, MO.
The EPA places St Louis City, MO in Zone 2 - a moderate-risk category, with a predicted average indoor radon level between 2 and 4 pCi/L. Zone maps predict an area's radon potential from geology and existing indoor readings; they say nothing about a specific house. Testing is the only way to know your own level.
87% of homes in St Louis City, MO were built before 1980, and 67% before 1950. Residential lead paint was banned in 1978, so housing age is the strongest available proxy for lead-paint exposure. This describes the county's housing stock, not any one home.
Modelled annual fine-particle pollution (PM2.5) in St Louis City, MO averages 8.7 µg/m³, within the EPA's annual standard of 9 µg/m³. These are CDC modelled county estimates rather than readings from a specific monitor.
How radon zones work · Air quality by county · Lead exposure guide