Where Does My Tap Water Come From?

by Caitlin Schott / Dec 27, 2021
Where Does My Tap Water Come From?

It’s easy to assume your tap water is safe—just flip on the faucet and what flows must be fine. But it’s a dangerous journey from the source to your tap; one that is unfamiliar to most of us. If you’re wondering where your drinking water comes from and what happens to it before it hits the tap, then this is for you. 

Tap Water Starts As Source Water

Tap water comes from two water sources collected by your local public water utility to distribute to your tap; surface water and groundwater. Surface water is water found in reservoirs, rivers, lakes, and streams that flows into public water supplies. Groundwater is underground water that’s found in small spaces between sand, soil, and fractured rocks known as aquifers. Groundwater is typically accessed through a private well, or pipe, drilled into an aquifer.


Source Water Is Often Contaminated When It Arrives To Public Water Systems

As you can imagine, there are all kinds of ways source water can become contaminated before it’s collected by local water supplies and served up as drinking water. That’s why we don’t simply stick straws in streams or drill our own wells and tip back a glass. 

We’ll go into more detail later, but everything from natural disasters to animal feces can contaminate source water. The bottom line is source water must be treated by your local public water system before water travels to your tap. All public water supplies are responsible for following water treatment practices designed to ensure tap water meets water safety standards set by the Safe Drinking Water Act and regulated by the U.S. Environmental Protection Agency (EPA). 

What About Water Treatment?

While water treatment is a well-intentioned way to make drinking water tap-ready, the drinking water standards surrounding it have been proven to be subpar—and in many cases, non-existent. Therefore, water treatment isn’t a cure-all for contaminated source water. 

As a matter of fact, the water treatment process can create and introduce new contaminants to tap water. For example, almost all public water systems disinfect water with chlorine and/or other disinfectants. Disinfection is a delicate balancing act. If anything goes awry, the result can be tap water littered with disinfection byproducts like Total Trihalomethanes (TTHMs) and Haloacetic Acids (HAA5).


The majority of current drinking water safety standards aren’t stringent enough to completely protect public health—and many dangerous contaminants that have been found in tap water remain unregulated today. Therefore, what the government deems “safe” likely isn’t safe enough.

From Treatment To Tap: The Scary Truth

Your public water supply is responsible for distributing tap water to your home via pipes. After treatment is completed at public water suppliers and treatment plants, water flows to your tap.

The problem is the journey from treatment to tap presents new dangers.

Even clean drinking water can be the victim of corroded pipes and aging infrastructure. That’s why, for example, lead contamination is a problem from New York to California

Source Of Tap Water Contamination 

  • Naturally occurring chemicals: Arsenic is just one of several dangerous drinking water contaminants that occur naturally, and can sneak into surface water undetected. While the chemical can be found in fertilizer or released through industrial processes, the Centers for Disease Control and Protection (CDC) points out arsenic can also dissolve out of certain rock formations. Other substances found naturally in rocks and soil can do the same, then end up in your drinking water. 

  • Agricultural activities: Fertilizers and pesticides used to control crops and pests can runoff into surface water and groundwater through storms, snow melt, and irrigation. The same goes for animal waste and feces. Studies show there is a direct connection between agriculture and drinking water quality

  • Industrial activities and waste: Improper disposal of chemicals and pollutants used for industrial processes can pollute drinking water, too. This ranges from gasoline spills to leaking storage tanks filled with hazardous chemicals. Dumping is another issue, as some factories are known to treat waterways like sewers.

  • Sewage and wastewater. Wastewater is nothing more than used water. In other words, water from our showers, toilets, and more. Wastewater can flow back into the environment and pollute our water systems with antibiotics, heavy metals, and more. 

  • Natural disasters: Wildfires can have an immediate and lasting impact on water supplies and quality as ash, chemicals, and contaminants can make their way into surface water. Plus, fire retardant can end up in water sources too. But wildfires aren’t the only natural disasters; storms and climate change pose risks too.

  • Water treatment: Ironically, water treatment can actually introduce new dangers to drinking water. For example, disinfectant byproducts detected in tap water like TTHMs and HAA5 are often the result of disinfecting water during treatment. 

  • Aging infrastructure: Like anything else, the millions of miles of underground and unseen pipes delivering water to your tap take a beating over the years leading to corrosion and damage. This is conducive to leaching chemicals, and is why lead contamination is so prevalent far beyond Flint, Michigan. 

  • Unregulated contaminants: Dozens of contaminants commonly detected in tap water are still unregulated today, while others are legally allowed in community water systems at worrisome levels. Legal limits for the majority of regulated contaminants haven’t been updated in decades and at time of publication, new and emerging contaminants detected in tap water have not been assigned regulations by the EPA in years. 

  • How To Protect Yourself & Your Loved Ones

    While many who don’t trust the tap turn to bottled water, the water inside and the packaging around it share the same concerns as tap water—plus more. That’s why your best bet is to get a water filter that goes above and beyond to virtually eliminate the covert and common contaminants known to plague the tap and pose health risks. If you want clean and safe drinking water you can count on, check out our full line of advanced filtration systems here


    Want To Know What’s In Your Tap Water?

    Our free database linked here compiles all of the test results from local public water supplies so you can see exactly what’s in your water. We’ve included the legal limit for each regulated contaminant as well as EWG health guidelines for every contaminant to give you a complete and transparent assessment of the water that flows out of your tap and the health effects detected contaminants pose.