Ask your public water distributor. Most of us get our water from a public distributor. They are required by law to give you information on what is in your drinking water. In fact, beginning in 1999, they will be required to send out this information to everyone living in their water district. Ask the Environmental Protection Agency or your local public health department.
Many people use well water.
If you do, you may be able to get information on what is in your water from either the EPA or a local public health office. Get it tested yourself. If you still can't get the information you need, hire someone to do a water test for you. You need different types of tests for different types of water pollution. One convenient option is to get your water tested by mail.