City water, also called municipal water, is drinking water supplied by a local government or public utility. It’s collected from natural sources, treated at a plant to remove contaminants, and delivered through a network of underground pipes to homes and businesses. About 286 million Americans get their water this way. The alternative is a private well, where individual homeowners pump groundwater from their own property and handle testing and maintenance themselves.
Where City Water Comes From
Municipal systems draw from two types of sources: surface water and groundwater. Surface water includes rivers, lakes, and reservoirs. Groundwater comes from underground aquifers, accessed through large public wells. In the U.S., public suppliers withdraw roughly 23,800 million gallons per day from surface water and another 15,200 million gallons per day from groundwater, making surface water the dominant source for most city systems.
Your annual water quality report (more on that below) will tell you exactly where your local supply comes from, including the name and location of the body of water.
How City Water Gets Treated
Raw water from a river or reservoir isn’t safe to drink. Treatment plants run it through a multi-step process before it reaches your tap.
First, plant operators add chemicals (typically aluminum or iron salts) that cause dirt and tiny particles to clump together. This is called coagulation. The water is then gently stirred so those clumps grow into larger, heavier clusters called flocs. Once the flocs are heavy enough, they sink to the bottom of large settling tanks in a step called sedimentation.
The clarified water on top then passes through several layers of filters made from sand, gravel, and charcoal. These filters catch remaining bacteria, parasites, viruses, dust, and dissolved chemicals. Activated carbon filters also remove unpleasant tastes and odors.
The final step is disinfection. Most plants add a small amount of chlorine, chloramine, or chlorine dioxide to kill any germs that survived filtration. Some facilities use ultraviolet light or ozone instead. A trace amount of disinfectant stays in the water intentionally so it continues killing bacteria as it travels through miles of pipes to your home. Chlorine or chloramine levels up to 4 parts per million are considered safe in drinking water, according to the CDC, though most systems maintain levels well below that ceiling.
What Gets Added Beyond Disinfection
Most city water systems also add fluoride to help prevent tooth decay. The current recommended level is 0.7 milligrams per liter. Community water fluoridation has been standard practice in the U.S. for decades, though some municipalities opt out. If your system exceeds a secondary fluoride standard of 2.0 mg/L (still below the enforceable safety limit of 4.0 mg/L), your utility is required to notify you.
Some treatment plants also adjust pH or add corrosion inhibitors to prevent the water from leaching metals out of older pipes on its way to your faucet.
The Pipe Network That Delivers It
Treated water leaves the plant and enters a distribution system: a sprawling web of pipes, pumps, valves, and storage tanks. Finished water sits in elevated tanks or reservoirs that use gravity to maintain pressure throughout the system. When you turn on a faucet, that stored pressure pushes water to your tap.
The pipes themselves vary in age and material. Older systems may include cast iron mains or lead service lines connecting the main to individual homes. Corrosion inside these pipes can introduce metals into the water, which is why treatment plants add corrosion-control chemicals and why the EPA has pushed aggressively to address lead pipes specifically.
A major federal rule finalized in 2024 requires every water system in the country to inventory all service lines and publicly share the results. Systems with lead or certain galvanized service lines must replace them, completing the work within 10 years of the compliance deadline at a rate of at least 10 percent per year. Full compliance with the replacement mandate begins in late 2027.
How City Water Is Regulated
The Safe Drinking Water Act gives the EPA authority to set legally enforceable limits, called maximum contaminant levels, for dozens of substances in public water systems. These primary standards cover health threats like lead, arsenic, nitrates, bacteria, and industrial chemicals. Utilities that exceed a limit must notify customers and take corrective action.
There’s also a set of secondary standards covering things that affect taste, smell, or appearance (like iron that turns water orange, or sulfur that makes it smell like eggs). These aren’t federally enforceable, though some states adopt them as binding rules.
One of the newest regulations targets a group of industrial chemicals called PFAS, sometimes called “forever chemicals” because they don’t break down naturally. In 2024, the EPA set enforceable limits for several PFAS compounds in drinking water for the first time. Two of the most common, PFOA and PFOS, now have a maximum limit of 4 parts per trillion, an extremely low threshold reflecting how persistent and potentially harmful these chemicals are. All water systems must comply by April 2029.
Your Right to Know What’s in It
Every city water system is required to send customers an annual Consumer Confidence Report (sometimes called a water quality report). This document lists every regulated contaminant that was detected, the level found, the legal limit, and the likely source of the contamination. It also includes specific information about lead testing results, corrosion control measures, and how to access the system’s service line inventory.
Reports must include plain-language explanations of key terms and a statement about risks for vulnerable populations, such as people with weakened immune systems. In communities where many residents speak a language other than English, the report must include information in that language about how to get a translated version. Most utilities post these reports on their websites, and you can also search for yours through the EPA’s online database.
City Water vs. Well Water
The biggest practical difference is responsibility. With city water, the utility handles testing, treatment, and infrastructure. You pay a monthly bill, but you don’t have to worry about pump maintenance, contamination testing, or power outages shutting off your supply (municipal systems have backup generators and storage towers that can supply water for weeks). With a well, all of that falls on you: regular water testing, pump replacement, and fixing problems when they come up.
Well water is untreated and naturally filtered through rock and soil, which many people prefer the taste of. It’s free of chlorine and fluoride. But it can contain bacteria, heavy metals, or agricultural chemicals that go undetected without routine testing. City water has a more standardized taste and consistent safety profile, but some people dislike the chlorine flavor or have concerns about aging infrastructure. A basic carbon filter at the tap handles most taste issues and provides an extra layer of filtration if you want one.