Well Water vs. City Water: What St. Louis Homeowners Need to Know About Filtration

If your home runs on a private well, your water supply works differently from your neighbor’s — and that matters. This is especially true as we head into the months when showers run longer, lawn sprinklers turn on, and pool season kicks into high gear.

While city water and well water share some of the same hard water challenges in the St. Louis area, well water owners carry an extra responsibility: no municipality is testing or treating your supply for you.

Jones Air & Water has served St. Louis and St. Charles homeowners since 1995. We see the same seasonal patterns year after year. Whether you’re on city water, a private well, or somewhere in between, here is what you need to know to keep your home’s water safe and clean.

What is the Difference Between City Water and Well Water in St. Louis?

City water in St. Louis and St. Charles comes from municipal systems like Missouri American Water, which draws heavily from the Missouri or Mississippi Rivers, or from the Elm Point Water Treatment Plant. This water is treated, tested, and delivered directly to your tap by a centralized utility. While municipal treatment removes most biological contaminants, it doesn’t resolve everything. Chlorine taste, hard water minerals, and some chemical disinfection byproducts still make it into your home.

On the other hand, well water is drawn directly from the groundwater beneath your property. Your total groundwater quality depends on the geology of your land, the depth of your well, and what’s happening above ground. Because no city treatment plant filters this water before it reaches your plumbing, seasonal weather changes impact well owners much more aggressively.

Hard Water in the St. Louis Region: By the Numbers

Hard water is a persistent challenge across the St. Louis metro, regardless of whether your supply comes from a well or the city. The Water Quality Association (WQA) classifies water above 7 grains per gallon (gpg) as hard, and above 10.5 gpg as very hard. Most of the St. Louis region falls squarely in the hard-to-very-hard range.

Local Water Hardness at a Glance

St. Louis City water measures approximately 7.8–12.8 gpg, depending on the area and source, ranging from hard to very hard. St. Charles city water comes in around 7.4–8.2 gpg.

Well water hardness varies more widely based on local geology, but homes drawing from limestone-bedrock aquifers in the Missouri River valley often see levels at the higher end of these ranges.

What does that actually mean? Scale accumulates in pipes and water heaters, soap and detergent work less effectively, and appliances wear out faster than they should. Installing a dedicated whole-house water softener neutralizes these minerals right at the source.

Why Should Owners Test Their Well Water Every Spring?

Spring runoff is the most significant water quality event of the year for well owners. As snow melts and heavy rains move through the region, water rushes across the surface carrying fertilizers, pesticides, animal waste, and sediment toward the groundwater your well draws from. Shallow wells are especially exposed. In areas with sandy soil or fractured rock, contaminants can reach your water table within hours of a significant rain event.

Common post-runoff contaminants include:

Bacteria (E. coli and coliform)
Nitrates from fertilizer use
Sediment
Pesticides and herbicides
Iron

Many of these are completely odorless and colorless, and you won’t know they’re present without a test.

When to Test Your Well Water

Jones Air & Water recommends annual well water testing for all private well owners in St. Louis, St. Charles, Jefferson, Lincoln, Warren, and Franklin counties. Test promptly after any flooding or significant ground disturbance, and schedule testing before summer water use ramps up. Sprinklers, pools, and increased shower demand all put more strain on your system and can mask changes in water quality that a test would catch.

A basic well water test should include: bacteria and coliform, nitrates, iron, hardness, and pH. Depending on your property’s location and well age, testing for additional contaminants such as arsenic, sediment, or volatile organic compounds may be appropriate. Our certified water treatment specialists can help you determine the right test panel for your situation.

Well Water Filtration: What Components Do You Actually Need?

A properly customized well water filtration system handles more than taste and odor. It addresses the specific issues that groundwater picks up on its way to your tap.

Here are the most common components Jones Air & Water installs for well water customers in the St. Louis and St. Charles areas.

Whole-House Sediment Filtration

A whole-house sediment filter catches sand, silt, and debris before they reach your appliances and plumbing fixtures. Spring is when sediment levels spike as rain pushes soil into groundwater. Filter replacement schedules should account for this. Filters that were fine in February may need attention by May.

Specialized Iron and Odor Removal

Iron is one of the most common well water problems in Missouri. It leaves rust stains on fixtures and laundry, and it makes water taste metallic. Jones Air & Water’s iron and odor removal systems address both dissolved iron and hydrogen sulfide (the rotten egg smell) that many well owners in this region encounter.

Smart Water Softeners

Hard water affects well and city supplies alike in this region. A water softener removes the calcium and magnesium that cause scale buildup, extends the life of water heaters and appliances, and helps protect your plumbing system. Jones Air & Water installs and services water softener systems sized for your household’s specific flow rate and hardness level.

UV Germicidal Treatment

A UV light purification system is the gold standard for chemical-free sterilization. It alters the DNA of biological pathogens like bacteria and viruses, neutralizing them completely. This is vital for families who want total protection against springtime bacterial spikes without introducing harsh chlorine-tasting chemicals into their drinking water.

Multi-Stage Reverse Osmosis Systems for Drinking Water

For pure drinking and cooking water, a reverse osmosis system removes the broadest range of contaminants, including nitrates, heavy metals, dissolved solids, and chemical residues that pass through standard filtration. Jones Air & Water offers whole-house and point-of-use reverse osmosis systems for both well and city water customers throughout the St. Louis metro.

Do City Water Customers Need Water Filtration Systems, Too?

Yes, city water customers aren’t immune to seasonal changes. Municipal systems drawing from the Missouri River and Meramec basin face the same spring runoff pressure. They handle it by increasing disinfectant levels, which can result in a stronger chlorine taste or odor from late spring through summer. Warmer water temperatures also affect how disinfection byproducts form and how algae behave in source water.

For city water households, the most common spring and summer complaints include increased chlorine taste, scale buildup on fixtures from hard water, and reduced effectiveness of soaps and shampoos. A whole-house water softener paired with a reverse osmosis drinking water system addresses all three. Families concerned about disinfection byproducts specifically should consider installing a whole-home carbon filtration system.

Your Seasonal Filtration Maintenance

Before pool season and summer water demand peaks, well owners should run through these steps with a certified water treatment professional:

Test for bacteria, nitrates, iron, hardness, and pH
Inspect and clean the wellhead, and check for any pooling or drainage issues around the casing
Replace sediment filters that handled winter and spring runoff
Verify UV lamp performance
Check water softener salt levels and schedule a system inspection if it hasn’t been serviced in the past year
Inspect your reverse osmosis filter to see if you need a replacement before summer cooking and drinking demand increases

Frequently Asked Questions

How often should a private well be tested in Missouri?

You should test your private well water at least once every year, preferably during the spring runoff season. If you notice sudden changes in water color, clarity, taste, or odor, or if your property experiences local flash flooding, you should schedule a professional water test immediately.

Why does my well water smell like rotten eggs in the summer?

A rotten egg odor is caused by hydrogen sulfide gas produced by naturally occurring sulfur bacteria in the groundwater table. This issue routinely intensifies during warmer months and during periods of heavy system usage. It can be safely resolved using a professional iron and odor removal system.

Can I monitor my home water filtration system from my phone?

Yes. Most water treatment systems installed by Jones Air & Water feature smart home integration. This allows homeowners to monitor real-time water usage, track filter life, and receive low-salt notifications directly through a mobile application.

Schedule a Free Water Test With Jones Air & Water

Do not guess when it comes to your family’s health and home appliances. Jones Air & Water provides completely free, no-obligation physical water testing for homeowners across Missouri (including St. Louis, St. Charles, Jefferson, Lincoln, Warren, and Franklin counties) and Illinois (including Madison, Monroe, St. Clair, Jersey, and Calhoun counties).

Our highly credentialed staff — holding elite Water Quality Association (WQA) certifications, Certified Installer CWS-V status, and DNR Certified Water & Wastewater Operator credentials — will precisely diagnose your supply and guide you toward the ideal setup for your budget.

Schedule your free water test before summer demand peaks.

You can be a filter or you can buy a filter!