Drinking Water: Where It Comes From and How It's Kept Safe

How much you need

Everyone needs to drink water. How much depends on your size, how active you are, and the weather where you live.

Where it comes from

Drinking water is a mix of two sources:

• Surface water — rivers, lakes and reservoirs.
• Groundwater — water from underground.

How safe it is

The United States has one of the safest water supplies in the world, but quality varies from place to place. It depends on:

• the condition of the source water;
• the treatment it gets — which may include fluoride, added to prevent cavities, and chlorine, added to kill germs.

Your yearly report

Your water supplier must send you a report every year. It tells you:

• where your water came from;
• which contaminants are in it.

Sources

Based on "Drinking Water," MedlinePlus, National Library of Medicine, drawing on the Centers for Disease Control and Prevention; a work of the United States government in the public domain.