The Ultimate Homeowner’s Guide to Understanding Where Drinking Water Comes From

1. Origin: Where Do We Get Our Water From?

All drinking water sources start in one of two places: on the surface or underground.

Surface water

Reservoirs, lakes and rivers — these open bodies of water are exposed to the atmosphere, weather and everything around them. A well-known example is the Missouri River at Fort Peck Reservoir in Montana, a water source for communities across the region.

Given surface water is open to the environment, it’s more vulnerable to outside contaminants. Common concerns include:

• Sediment
• Agricultural chemicals such as pesticides and nitrate
• Industrial runoff
• Algae and microorganisms

Groundwater

Groundwater comes from aquifers — large underground formations of rock, sediment or soil that hold water. Think of an aquifer as a massive underground reservoir. The Prairie du Chien-Jordan aquifer, which stretches across parts of Minnesota, Wisconsin and Iowa, is an example, supplying drinking water to communities across the Upper Midwest.

Since groundwater is naturally filtered through rock and soil as it moves underground, it often comes with fewer microbial concerns than surface water. However, it picks up minerals along the way, a leading cause of hard water. Common groundwater concerns include:

• Dissolved minerals such as calcium and magnesium (the primary cause of hard water)
• Naturally occurring radioactive elements such as radon and radium

A note on private wells

If your home has a private well, your water follows a much shorter path directly from the ground into your home, with no municipal treatment in between. That speed and simplicity is convenient, but it also means fewer safeguards. Well owners are responsible for testing and maintaining their own water supply.

Find your water’s origin

Not sure whether your home is served by surface water or groundwater or where exactly it comes from? Start with a simple web search: “[your city, state] water quality report.” Most utilities publish an annual water quality report, also called a Consumer Confidence Report (CCR), that identifies the source of your water and its current status.

For example, the city of Hopkins, Minnesota, publishes its water quality report at hopkinsmn.com/500/Water-Quality. Your city likely has something similar.

2. Treatment: Making Water Safer to Drink

Before water reaches your home, it goes through a regulated treatment process designed to make it safer for consumption. Treatment requirements are set via the U.S. Environmental Protection Agency (EPA) under the Safe Drinking Water Act.

How a municipal water treatment plant works

The treatment process varies by facility but most follow these core steps:

1. Clarification: Large particles including sediment, dirt and debris, are removed through settling and coagulation.
2. Filtration: Water is filtered, capturing particles that clarification missed, including select microorganisms.
3. Disinfection: An approved disinfectant, usually chlorine, is added to kill harmful bacteria, viruses and other pathogens. This step is critical to why waterborne diseases such as cholera and other common public health threats are now very rare in the United States.

What gets added during municipal treatment

• Fluoride: Many water utilities add fluoride to drinking water. The CDC recommends a level of 0.7 milligrams per liter (mg/L) to help prevent tooth decay while keeping exposure at a safe level.
• Disinfection byproducts: When chlorine is used to disinfect water, it can react with naturally occurring organic matter such as encompassed plant material that’s already present in the water. This reaction creates chemicals called disinfection byproducts (DBPs). The EPA regulates DBPs and sets maximum contaminant levels for the most common types. Water utilities must test regularly and notify customers if those limits are exceeded.

3. Distribution: Water’s Journey Under Your Street

Once treated, municipal water is distributed through a network of underground pipes carrying water from treatment facilities to homes and businesses throughout their communities. The water main is the primary pipe in this system.

Water mains form a highway that runs under city and suburban streets. Water mains are typically made of modern PVC, cast iron or ductile iron. They are owned and maintained by cities and their respective utilities and are installed when a neighborhood or subdivision is first built.

Many pipes installed in the early to mid-20th century were made of cast iron, which has a lifespan of 75 to 100 years. When these older water mains break, contaminants are introduced to the water supply and may sometimes trigger boil water advisories.

4. Home Plumbing: The Final Stretch

The water main stops at the property line of municipal homes. From there, a smaller pipe called the service line carries water from the main to the home. Unlike the water main, service lines are owned and maintained by the homeowner.

This final section of pipe is where most water quality risks occur, which include lead contamination. The risk is higher in service lines due to large amounts of water that idles for extended periods, increasing the potential for leaching, and the surface-area-to-volume ratio of the service line to home plumbing.

5. Five-Step Action Plan

While understanding how water reaches your home is helpful, the question is what can you do about it when you’re not satisfied? Follow these five steps.

1. Read your water quality report. Every municipality is required to publish an annual consumer confidence report. In this document you can find information about detected contaminants, their levels and notes with any violation information.
2. Investigate your service line. Find the pipe where your water supply enters your home. Usually it’s in the basement near the front or side of the house. If your neighborhood is older and your pipe is dull gray and can be scratched with a coin or key, then it may be made of lead.
3. Flush your taps. Before using tap water for cooking and drinking each day, run your tap with cold water for a moment. This will clear out water that sat in the pipe overnight, reducing potential exposure to leached materials.
4. Use cold water for drinking and cooking. Always draw from the cold tap when water will be consumed. Cold water is safer and cleaner, as contaminants like lead leach into hot water.
5. Get a professional assessment. To get a complete picture of your water, consult a professional. EcoWater offers free in-home water tests that identify specific water concerns in your area. During the appointment, your local EcoWater Expert will share your test results and recommend a solution that’s tailored to your specific needs.

6.  Quality Assurance: Make an Informed Decision

If you have municipal water, it travels a long way before it reaches your faucet, so it makes sense that different variables and contaminants impact what eventually makes its way out of your tap. But there’s good news: you don’t need to become an expert to get better water quality.

Follow the steps outlined above and you’ll be on your way to not only knowing what’s in your water, but what can be done to fix it. That way, you can enjoy water on your terms. When you’re ready, find your local EcoWater Expert to schedule your free water test.