What Is Tap Water & Where Does It Come From?

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How much do you know about the water that comes out of your tap? In this guide, we’ve shared a definition of tap water and discussed where it comes from in the US.

📌 Key Takeaways:

  • Tap water is water that’s supplied to customers in urban areas in the United States.
  • Tap water comes from two water sources: surface water sources and groundwater sources.
  • Municipal drinking water is treated at public water treatment facilities before it is delivered to our homes via distribution pipes.

🚰 What Is Tap (Municipal) Water?

Tap water, also known as municipal water or public water, is water that’s supplied to households, businesses, and other buildings through a system of pipes and treatment plants. It’s the most common source of drinking water for people around the world, and is regulated by government agencies to ensure its safety and quality.

Tap water is typically sourced from:

  • Surface water sources, such as rivers, lakes, and reservoirs
  • Groundwater sources, such as underground aquifers

Once it’s collected, tap water is treated to remove or kill impurities like bacteria, viruses, algae, sediment, heavy metals, and chemicals. The treatment process may involve several steps, including filtration, disinfection, and pH adjustment (discussed in more detail later in this article).

After treatment, tap water is distributed through a network of pipes to homes and buildings, where it can be accessed through faucets, showers, and other outlets. Most tap water systems use a combination of gravity and pumps to send the water through the pipes.

Filling a glass with tap water

🤔 Where Does Tap Water Come From?

Tap water in the United States comes from a variety of sources, including lakes, rivers, reservoirs, and underground aquifers. The source of tap water for a particular community is usually determined by its location and the availability of water sources in the area.

Surface Water Sources

In most parts of the country, tap water is sourced from surface water sources, like lakes and rivers. Surface water is collected in reservoirs: large man-made or natural bodies of water that store water for treatment and distribution to communities.

Because they’re above-ground, surface water sources are vulnerable to contamination from pollutants and are typically treated with chemicals like chlorine or ozone to kill bacteria and other harmful contaminants. More on how tap water is treated later.

Colorado river

Groundwater Sources

Other communities in the US get their tap water from underground aquifers. These are layers of rock, sand, or gravel that contain water that can be pumped to the surface or accessed from natural springs.

Aquifers are a common source of drinking and irrigation water in areas with little or no surface water, and they’re generally considered to be a reliable source of clean, safe drinking water. However, aquifers can be depleted if they’re over-pumped, which can lead to shortages of water and problems with water quality.

🔎 How Is Tap Water Treated?

Before drinking water is sent to our homes via community water systems, it’s first treated to make it safe for drinking.

Municipal water treatment is the process of filtering water for use by the general public. Let’s take a closer look at each of the stages involved in the treatment process:

Stage 1: Source Water Collection

The first step in drinking water treatment is to collect source water from a natural body of water. The water is typically pumped from the source into a treatment plant, where it will undergo various purification processes.

Stage 2: Pretreatment

Before the water can be treated, it’s first screened to remove large debris and sediment. This is typically done using a series of screens, filters, and sedimentation basins.

Slow sand filtration plant

Stage 3: Primary Treatment

During primary treatment, the water is further clarified with chemical coagulants and flocculants, which cause impurities and contaminants to clump together and settle to the bottom of a sedimentation tank. The water is then filtered through sand and gravel to remove any remaining solids.

Stage 4: Secondary Treatment

After primary treatment, the water undergoes secondary treatment to remove any remaining organic matter and bacteria. This is typically done using a combination of biological processes, such as the use of bacteria to break down organic matter, and physical processes, like sedimentation and filtration.

Stage 5: Disinfection

Once the water has been treated, it’s disinfected to kill any remaining bacteria or viruses. This is done using chlorine, ozone, or ultraviolet light.

Municipal drinking water treatment plant

Stage 6: Distribution

The final step in the water treatment process is to distribute the purified water to drinking water customers through a network of pipes and pumping stations. The water is usually held in reservoirs or storage tanks before it’s distributed to ensure that a consistent supply is available to meet demand.

👨‍🔧 You can learn more about the stages of treating a public drinking water supply in our guide on Water Treatment Basics 101.

🧐 How Does Water Get To The Tap?

Water from the tap can seem like something of a magical mystery to those of us who don’t know how it gets there.

Let’s explore how water gets from a treatment facility to our homes.

Once drinking water has been treated, it’s pumped through a network of pipes to distribution centers, which are responsible for delivering the water to homes and businesses. These pipes may be made from steel, plastic, or concrete. Old water distribution pipes are sometimes made from lead.

Water that travels through the pipes is under pressure to ensure that a steady supply of water is provided, even at peak usage. This pressure is created by pumps at the water treatment plant. The normal residential water pressure is usually 45-80 PSI.

When drinking water reaches your home, it enters your main water line, which is usually found underground. From there, it’s distributed to various points in your home through smaller hot and cold water pipes.

Finally, the water is ready to be used at your tap.

Water distribution networks through water pipes

🩺 Is Tap Water Safe To Drink?

Regardless of the source, all municipal drinking water in the United States is regulated by the Environmental Protection Agency (EPA), which sets standards for the quality and safety of tap water. Water utilities are required to regularly test and report the quality of their tap water to ensure that it meets these standards.

For this reason, it’s generally safe to drink tap water. However, public drinking water can sometimes contain contaminants that can cause health problems. The main issue is that EPA guidelines only require water utilities to reduce contaminants down to trace levels – but some experts argue that even at trace levels, these contaminants could be harmful to our health.

Plus, these guidelines only apply to a drinking water supply immediately after water treatment, and don’t account for the contaminants that might enter the water through water supply pipes. Lead pipes are still used as water distribution pipes around the country.

Examples of contaminants commonly found in public drinking water supplies are:

  • Sediment
  • Heavy metals like lead
  • Disinfection chemicals like chlorine
  • Nitrates
  • Minerals like fluoride
  • Radiological contaminants like uranium

Whether or not you’re happy to drink trace amounts of toxic contaminants is a personal preference. You might choose to use a water filter or purification system to remove any impurities from tap water before you drink it – Explore our in-depth review of the best water filters for home use.

Related Article: Top 11 Countries With The Best Water in the World

🆚 Tap Water Vs Bottled Water

Now we know more about municipal water and where it comes from, let’s take a look at the difference between water from a tap and bottled water products.

One of the primary differences between tap water and bottled water is the source of the water. Tap water is sourced from a public water supply, which is regulated by the EPA to ensure it meets certain standards for safety and quality.

Bottled water, on the other hand, can come from a variety of sources, including springs, wells, and municipal water supplies. Bottled water is regulated by a separate governing body: the Food and Drug Association (FDA).

Tap water is more readily available than bottled water, since you can turn on your tap and get clean drinking water straight away whenever you want it.

With that said, some people prefer to pay for bottled water due to concerns about the quality and taste of tap water. While tap water is regulated by the government, it can still contain contaminants such as chlorine and lead.

Bottled water, on the other hand, is often purified through a variety of methods, including reverse osmosis, which removes contaminants and improves the water’s taste. Don’t assume that bottled water is always pure, though – some bottled water products are simply bottled tap water.

👨‍🔧 Our comparison guide looks in more detail at the differences between faucet water and bottled water.

Tap water vs bottled water

📑 Final Word

Tap water is something that many of us take for granted. Having clean drinking water in your home’s plumbing system is a luxury. But that doesn’t mean that municipal water supplies are 100% pure and healthy.

Many people choose to filter their home’s tap water supply to remove contaminants caused by aging distribution systems and substandard public water treatment. It’s worth testing your water to find out what it contains and decide whether or not you’re comfortable drinking trace contaminants.

  • Jennifer Byrd
    Water Treatment Specialist

    For 20+ years, Jennifer has championed clean water. From navigating operations to leading sales, she's tackled diverse industry challenges. Now, at Redbird Water, she crafts personalized solutions for homes, businesses, and factories. A past Chamber President and industry advocate, Jennifer leverages her expertise in cutting-edge filtration and custom design to transform water concerns into crystal-clear solutions.

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