Drinking Water Utility Systems

The journey drinking, or potable, water takes to reach your tap can be a long one. In a regulated system such as yours, that involves considerable infrastructure, skilled operators, and numerous checks along the way to ensure it reaches your tap as clean, safe, reliable drinking water.

Drinking Water Treatment
Simplified Process

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Sources of Drinking Water

Your drinking water’s journey starts at one of two sources:

Groundwater

Pumped from aquifers (underground layers of porous rock) to the surface through wells. Groundwater was traditionally considered to be of higher purity than surface water, however; chemical contamination is an increasing concern across the US.

Surface Water

Pumped from freshwater lakes and rivers. Surface water is more susceptible to contamination, so usually requires more treatment.

You can learn where your drinking water comes from in your community’s Water Quality Reports.

It’s important to note all drinking water contains some naturally occurring elements that aren’t harmful to health, and some provide low levels of nutritional value and enhance its taste.

Treatment of Groundwater

Water is pumped from the well to the water treatment plant – sometimes a distance of several miles. Once it reaches the treatment plant, it’s passed through mechanical filters to remove particles, such as organic matter, silt, clay, iron, and manganese. If necessary, it’s passed through a chlorination or UV process to remove any bacteria, viruses, and protozoan parasites. Groundwater is regularly tested at source, and after it has passed through the treatment process.

Treatment of Surface Water

Surface water is more susceptible to contamination, so usually requires more complex treatment. Water is first pumped from reservoirs, lakes, or rivers; normally from depth where it is less disturbed. Once it reaches the water treatment plant, it passes through a sedimentation and aeration process. Aeration releases any volatile gases, and coagulating agents help filter out small particles in large settling tanks. It’s then sent through a series of long filtration tanks, which use gravel, sand, or activated carbon to further remove particles and pollutants. Finally, it passes through a chlorination and/or UV process to remove any remaining bacteria, viruses, and protozoan parasites. Surface water is regularly tested at source and throughout the treatment process.

Storage & Distribution

Once treated, drinking water is stored in large tanks and/or water towers. This ensures a reliable and constant supply for the community’s needs, including fire suppression (fire hydrants and reservoirs). The large volume of these tanks also increases the water’s pressure, reducing the need for additional pumps in the system.

From the storage tanks, an extensive network of watermains, made from iron or PVC, deliver clean pressurized water to homes and businesses. Watermain networks run under streets and sidewalks and can be many miles longer than street infrastructure. Customers connect, or “tap” into these public watermains through private service lines. Service lines often have a shut-off valve, or “curb stop”, and water meter installed before the line enters the building, though this can vary by jurisdiction and age of the installation. More information about service lines and meters can be found on the Water Meters & Leaks and Lead & Lead Service Lines pages.

Water Myths & Facts

Myth: “New” water is better than treated water.

Fact: There is very little water on Earth that is “new.” Most of our water has been touched by some type of human or animal activity. Even in pristine wilderness areas, studies have found bacterial contamination. Therefore, it’s always best to drink water that you know has been treated.

Myth: We shouldn’t have to think about drinking water.

Fact: We can no longer take our drinking water for granted. Public participation is vital to protecting our water resources, building adequate treatment plants, improving water delivery, and enacting appropriate legislation.

Myth: There are more pollutants in drinking water today than there were 25 years ago.

Fact: Not necessarily. There may be more contaminants that can enter our water sources today, but we did not have the technology to know what was in our drinking water 25 years ago. Today we have sophisticated testing instruments that enable us to understand more about our water than ever before. With this knowledge, the drinking water community is taking steps to treat what’s in our water, curb the flow of pollution, and keep our water safe and wholesome.

Myth: Using a home water treatment device will make water safer and more healthful to drink.

Fact: Some people use home water filters to improve the taste, smell, or appearance of their tap water, but they do not necessarily make the water safer or more healthful to drink. Additionally, all home treatment devices, regardless of the technologies they use, require regular maintenance. Water quality problems may result if care is not performed correctly.

Myth: Lead occurs naturally in drinking water.

Fact: Lead is a relatively common metal, used by humans throughout history, but natural lead contamination of drinking water is exceptionally rare. The most common source of lead in drinking water is the plumbing in your home. To learn more about lead in drinking water, its health risks, and how to protect your household, please visit our Lead & Lead Service Lines pages.