BEFORE LONG, YOUR TAP WATER WILL HOLD NO SECRETS.(MAIN)

Byline: WENDY KOCH Times Union Washington bureau

Washington For the first time, most Americans soon will receive detailed annual reports on the safety of their tap water.

They will learn the source of their drinking water, whether it contains chemicals or contaminants and what the health consequences might be.

They'll learn what, so far, has often been kept secret. Now, the secret's out.

The new Safe Drinking Water Act, which Congress revised in August, requires most water utilities to provide these ``plainly worded'' reports to customers. They'll begin their mailings within two to three years.

Small and medium-size utilities, those serving 500 to 10,000 people, may be allowed to publish the information in local newspapers, rather than mailing …