Refer to EPA and state lists of certified water testing laboratories

The EPA works closely with each state to implement clean water standards. Each state water quality certification officer in turn readily provides the names and contact information of certified water quality testing services, both in the state or outside of it.

I recommend: The EPA has an index cataloging each state's certified laboratories for testing water. DMOZ, an online open directory project, keeps an active, ongoing list of water quality testing labs.

Use state lists to find water testing company certifications and analytical parameters

When you reach a lab, ask about analysis turnaround times, quality assurance/quality control and corrective action methods. In some cases, you may need to go outside your state to get the water analysis services you need.

I recommend: Arizona updates its list of commercial drinking water testing laboratories every 24 hours. North Carolina lets website visitors query by contaminant types for certified water testing labs.

Find laboratories for testing water that have accreditation from national organizations

The NELAC Institute (TNI) monitors performance of water testing laboratories via a national accreditation program. TNI, which evolved from the National Environmental Laboratory Accreditation Conference (NELAC), reviews laboratory procedures and standards for its accreditation program, which goes beyond state certification. Founded in 1937, the American Council of Independent Laboratories (ACIL) defines standards of conduct for member laboratories and allied organizations.

I recommend: NELAC sorts lists of accredited labs with notations on water testing labs. ACIL has a laboratory referral service with descriptive paragraphs and direct online links to water testing laboratories.