More often than not, Missourians turn on their faucet and let the tap water flow into a glass without stopping to wonder, Where does my water actually come from? Typically, people no longer have to scoop a pail of water from the river or creek and trudge home with it. Instead, a simple twist of a knob can instantly gain them access to water.
Most of Missouri’s drinking water comes from either surface water, like rivers and lakes, or groundwater, which is underground water that fills spaces in soil and rock. Each type of water has a different treatment process and offers different benefits.
Surface water
The majority of Missourians get their drinking water from surface water, such as rivers, lakes, streams, and reservoirs. By far, the largest source of drinking water for Missourians is surface water from the Missouri River, especially for those living in highly populated cities, according to the Missouri Department of Natural Resources (MDNR).
Missouri’s surface water comes from precipitation and water runoff, says Bob Bacon, state hydrologist for MDNR. Water runoff occurs when there is more water than the land can absorb, so it flows into nearby surface water areas. Once the bodies of water are filled with runoff water and precipitation, the water is sent to a water treatment plant, where it is filtered and disinfected for consumption. From there, it becomes drinking water that is sent to faucets.
Groundwater
While more of Missouri’s population gets their drinking water from surface water, there are more groundwater drinking systems than surface water systems in the state. Nearly all private rural water supplies are furnished by groundwater, says Scott Kaden, groundwater section chief of the Missouri Geological Survey–Water Resources Center at the MDNR.
“If you draw a line from Hannibal to Columbia to Sedalia to Joplin, the areas northwest of this line typically have poor groundwater quality, with the exception of alluvial aquifers associated with major rivers,” Scott says. “For the most part, a well can be drilled anywhere southeast of this line and will be able to produce high quantities of high-quality groundwater.”
Public water systems are managed by agencies like local or state governments, while private water systems are managed by for-profit companies, meaning they are not regulated by the government in the same way.
Aquifers, bodies of permeable rock that can contain or transmit groundwater, are where our groundwater comes from. Well water, which is how many people get water into their homes, is pumped from aquifers. The water in Missouri’s aquifers comes primarily from precipitation percolating into the ground, Scott says. Missouri has been divided into eight major groundwater provinces. The largest, most extensive aquifer in Missouri is the Ozark Aquifer in the Salem and Springfield Plateau groundwater provinces, according to the MDNR.
Comparing the two
Surface water has to be treated and processed to a far greater extent than groundwater to make it potable for consumption, while—for the most part— groundwater is ready to consume straight from the well with no treatment, explains Scott. There are some cases in which groundwater must be treated, but those are relatively few, so using groundwater is easier and cheaper, Scott adds. Groundwater can become polluted from human activity or natural conditions.
“Surface water systems definitely have more stringent requirements to meet in order to ensure the system provides water that meets treatment technique standards,” says Austen Dudenhoeffer, environmental analyst for MDNR. “In Missouri, there are a substantial number of groundwater systems concentrated south of the Missouri River that have no treatment because the groundwater quality meets all applicable state and federal standards.”
With the difference in treatment processing comes a difference in taste and effect on appliances. Groundwater in Missouri has a more mineral taste compared to surface water, due to the water flowing through limestone and the high levels of calcium and magnesium in the water, Bob says. Surface water has more of a chlorine taste, due to the extensive treatment it has to go through before becoming safe drinking water, he adds.
Another difference between surface water and groundwater is the build-up that happens to appliances. Groundwater, also referred to as hard water, builds up minerals on appliances that come in contact with it. Surface water, also known as soft water, typically doesn’t.
“It will make quite a big difference, like in your water heater. With softer water, your water heater will last longer, and you won’t get a ring around your bathtub,” Bob says.
The danger of lead contamination in Missouri’s water
While all lead service lines, also known as lead pipes, were banned in 1989, not all lead pipes have been replaced in Missouri. In 2023, the United States Environmental Protection Agency (EPA) reported that Missouri had more than 200,000 lead service lines; however, that same year the Natural Resources Defense Council, an environmental nonprofit, estimated that there was more than 300,000 lead service lines—making Missouri the sixth highest state in the nation for its number of lead pipes.
No amount of lead in water is safe to drink, according to the EPA. It can cause learning delays for children, a lower IQ, hyperactivity, slow growth, seizures, and even death. In fetuses, it can cause premature birth and birth defects. In adults, it can cause heart, fertility, and kidney issues. The greatest risk for lead toxicity is fetuses and children under six years old.
Lead can get into drinking water in multiple ways: through the lead fixtures and pipes used to transport water into a home, from naturally occurring lead deposits in groundwater, or from past or previous lead mining deposits entering a water source.
The EPA announced in May 2024 that more than $44 million will be put toward the replacement of lead pipes in Missouri. The initiative was part of former president Joe Biden’s investment in America’s Agenda, a national healthcare alliance. Based on the EPA’s announcement in October 2024 of the new Lead and Copper Rule Improvements, the deadline for lead service line replacement is 2037, says Austen Dudenhoeffer, environmental analyst for MDNR.
How to reduce lead in your drinking water
- Use your filter properly: Using a filter can reduce lead in drinking water. If you use a filter, make sure you use one that is certified to remove lead. Read the directions to learn how to properly install and use your cartridge and when to replace it. Using the cartridge after it has expired can make it less effective at removing lead. Do not run hot water through the filter.
- Clean your aerator: Regularly clean your faucet’s screen (also known as an aerator). Sediment, debris, and lead particles can collect in your aerator. If lead particles are caught in the aerator, lead can get into your water.
- Use cold water: Use only cold water for drinking, cooking, and making baby formula, which you can warm after mixing. Remember, boiling water does not remove lead from water.
- Run your water: The more time water has been sitting in pipes, the more lead it may contain. Before drinking, flush your home’s pipes by running the tap, taking a shower, doing laundry, or doing a load of dishes. The amount of time to run the water will depend on whether your home has a lead service line or not and the length of the lead service line. Residents should contact their water utility for recommendations about flushing times in their community.
- Learn if you have a lead service line: Find out if the pipe that connects your home to the water main (called a service line) is made from lead. Ask your water utility, or if your utility doesn’t have information, a licensed plumber may be able to assist. Learn how to find lead pipes in your home from the EPA’s step-by-step guide called Protect Your Tap.
- Learn about construction in your neighborhood: If you have a lead service line, you should be aware of any nearby construction or maintenance work that could disturb the line. Ground tremors from construction may suddenly cause more lead to be released from lead service lines in the area.
- Have your water tested: Contact your water utility to have your water tested and to learn more about the lead levels in your drinking water.
All information according to the EPA.
Other possible contaminants
Missouri often experiences other contaminants in its drinking water such as:
- Fecal coliform and E. coli bacteria, which can cause diarrhea, stomach pain, and other digestive symptoms. It is caused by agricultural and storm runoff, untreated human sewage, and leaking septic systems.
- Arsenic, which can cause heart, lung, liver, immune, nervous, or reproductive system disorders, digestive issues, and cancer. Since arsenic is naturally occurring in the earth’s crust, arsenic is more common in groundwater.
- Nitrates, which can cause oxygen deprivation for infants and increase the risk of cancer. Nitrates enter water from fertilizer runoff, septic tanks, and urban runoff.
- Fluoride, which is dangerous in excessive amounts and can damage bone tissue and cause teeth discoloration. Fluoride has been found to be naturally occurring in some groundwater sources in Missouri.
To get your drinking water tested by a certified chemical laboratory, call 573-526-3315 or email [email protected]. To report contaminates in your drinking water, call 573-751-1300
This article was originally published in the January/February 2025 edition of Missouri Life.
