Who will be drinking the water? If children, a pregnant person, or an individual with health issues will be drinking the water, there are specific contaminants, such as lead and nitrates, that you need to check for. Talk to your doctor or local health department about your specific medical conditions.

Are there natural contaminants I need to be concerned with? In some areas, there may be known natural contaminants. For more information about determining specific contaminants in your area, check out this article, "How can I determine if a specific contaminant is present in my local area?"

How deep is my well, and what kind is it? Depending on your well depth and type, you may be at a higher risk for certain contaminants. For example, a shallow well may be influenced by surface water runoff, while a deep bedrock well may have naturally-occurring heavy metals. Knowing this information will help you determine what contaminants could be reaching your well, so you know what to test for. Your well log can provide you this information.

How old are your pipes? Pipes can deteriorate or corrode over the years which can introduce contaminants to your well water. Older pipes may be made of materials such as lead that can pose a potential problem. Knowing about your plumbing will help you to know if you need to be concerned about certain contaminants.

Your local health department, or other agencies (e.g. cooperative extension, DNR, etc.) that regulate or are familiar with wells: They can provide information on local water quality issues and recommend specific tests base on your area.

A state-certified laboratory: You can find a state-certified laboratory at the National Environmental Laboratory Accreditation Management System's webpage. If you do not know a specific laboratory in your area, enter your state and then filter the results by city.