Denver's Tap Water: Are Minerals Killing Your Gut Biome?

By Franklin Everett Shaw

May 12, 2026

Is your gut feeling a little…off? It might be more than just that questionable burrito you had last week. The water you drink every day, even seemingly pristine Denver tap water, could be playing a subtle role in your overall well-being.

Let’s dive deep into the mineral makeup of Denver’s water supply, specifically focusing on calcium and magnesium. Denver sources its water from mountain snowmelt, primarily the South Platte River and the Colorado River basins. This water, while generally considered high quality, naturally picks up minerals as it flows through the Rocky Mountains.

Denver Water publishes annual water quality reports, readily available on their website. These reports detail the levels of various minerals and contaminants. Typically, Denver’s water falls within acceptable EPA standards, but the mineral content, particularly calcium and magnesium, can be significant.

Why should you care about calcium and magnesium in your water? These minerals contribute to water hardness. Hard water, while not a health hazard in itself, can lead to scale buildup in pipes and appliances, and some people find it less palatable. More importantly, excessive intake of these minerals could, theoretically, impact your gut microbiome.

Let’s be clear: there’s no definitive, large-scale study directly linking Denver’s tap water to specific gut health problems. However, the gut microbiome is a delicate ecosystem, and changes in mineral intake can influence its composition. High levels of calcium, for example, can affect the pH balance in the gut, potentially favoring certain bacterial species over others. Magnesium, while essential for many bodily functions, can have a laxative effect in high doses, which could also disrupt the gut’s equilibrium.

So, how do you know what’s in your Denver tap water? Here’s a step-by-step guide to testing your home water for mineral content:

Review Denver Water’s Annual Report: Start by downloading the latest water quality report from Denver Water’s website. This will give you a general overview of the mineral levels in the water supply for your area.
Purchase a Home Water Testing Kit: You can find these kits at most hardware stores or online retailers like Amazon. Look for a kit that specifically tests for calcium and magnesium hardness. API Aquarium Test Kits are a good option, and are available at most pet stores. While designed for aquariums, they are accurate and affordable.
Collect Your Water Sample: Follow the instructions provided with your testing kit. Typically, this involves collecting a sample of your tap water in a clean container. Let the water run for a minute or two before collecting the sample to ensure you’re getting a representative sample of the water in your pipes.
Perform the Test: Carefully follow the instructions in your testing kit to perform the test and interpret the results. The kit will usually provide a color chart or other method for determining the mineral levels in your water.
Research Local Water Treatment Reports: Denver Water provides detailed information about the treatment processes used to ensure water quality. Understanding these processes can give you insights into how the water is treated before it reaches your home.

Now, let’s say your test reveals high levels of calcium and magnesium. What can you do?

Here are some actionable steps to mitigate potential negative effects on your gut microbiome:

Water Filtration: Consider investing in a water filtration system. A reverse osmosis (RO) system is highly effective at removing minerals, including calcium and magnesium. However, RO systems also remove beneficial minerals, so you might want to consider remineralizing the water afterward. A more targeted approach is a water softener, which specifically targets calcium and magnesium.
Probiotic Supplementation: Probiotics can help support a healthy gut microbiome by introducing beneficial bacteria. Look for a probiotic supplement that contains a variety of strains, including Lactobacillus and Bifidobacterium. Consult with a healthcare professional to determine the best probiotic for your individual needs.
Dietary Adjustments: If you’re concerned about excessive mineral intake, consider adjusting your diet to include more foods that support gut health, such as fiber-rich fruits and vegetables, fermented foods like yogurt and sauerkraut, and prebiotics like garlic and onions.
Monitor Your Symptoms: Pay attention to any changes in your digestive health, such as bloating, gas, or changes in bowel movements. If you experience persistent symptoms, consult with a healthcare professional.

A common mistake people make is assuming that all water filters are created equal. A simple pitcher filter, like a Brita, will improve the taste and odor of your water by removing chlorine and some sediment, but it won’t significantly reduce mineral content. You need a more robust filtration system, like a reverse osmosis system or a water softener, to effectively remove calcium and magnesium.

Another pitfall is relying solely on home water testing kits. While these kits can provide a general indication of mineral levels, they are not as accurate as laboratory testing. If you’re seriously concerned about the mineral content of your water, consider sending a sample to a certified water testing laboratory for a more comprehensive analysis.

Remember, the link between Denver’s tap water and gut health is theoretical and requires further research. However, taking proactive steps to manage your mineral intake and support a healthy gut microbiome is always a good idea. By understanding the mineral composition of your water, testing your home water, and implementing appropriate filtration and supplementation strategies, you can take control of your health and well-being. Don’t just blindly trust the tap; investigate and make informed choices.