Water Testing 101

Direct answer: Choose water tests based on the water source, property history, and decision you need to make. Public-water customers should begin with the utility’s annual Consumer Confidence Report and test at the tap when plumbing, lead, taste, odor, or a local incident raises concern. Private-well owners are responsible for their own water and should use a certified laboratory and local health guidance.

Public water versus private wells

Public water systems monitor regulated contaminants and publish annual results. Those results describe the system, not necessarily conditions created by a building’s service line, fixtures, filters, or stagnant plumbing. Private wells are not managed like public systems; location, depth, construction, nearby land use, flooding, and maintenance influence the testing plan.

When should water be tested?

• After flooding, loss of pressure, repairs, or a change in taste, odor, or color
• When purchasing a property served by a private well
• When an infant, pregnant person, or medically vulnerable occupant will use the water and a clinician or health department recommends testing
• When nearby contamination, agricultural activity, septic failure, or a regulatory notice creates a specific concern
• When older plumbing or service lines create a lead or copper question

Common analytes

Basic private-well panels often include total coliform and E. coli indicators plus nitrate/nitrite, but local conditions may call for metals, minerals, pesticides, volatile organic compounds, PFAS, radionuclides, or other parameters. Testing everything is costly and may not be useful. Ask the county health department or a qualified water professional which hazards are plausible at the site.

Why sampling technique matters

A laboratory result is only as reliable as the sample. Use laboratory-provided containers, follow preservation and holding-time instructions, and do not rinse sterile or chemically preserved bottles. The selected tap, aerator removal, flushing time, disinfectant neutralizer, and first-draw versus flushed protocol depend on the analyte. Record the location, date, time, water treatment status, and sampler.

How to read a laboratory report

• Result: The measured concentration or presence/absence finding.
• Unit: For example, milligrams per liter or micrograms per liter. Units must match before comparing values.
• Detection/reporting limit: The lowest amount the method reports reliably.
• Qualifier: A code indicating estimated results, holding-time issues, interference, or another limitation.
• Comparison value: The applicable maximum contaminant level, health advisory, or local criterion. Not every detected substance has the same type of benchmark.

What to do after an unexpected result

Do not select treatment from a single number without confirming the sample and benchmark. Contact the laboratory or local health authority, determine whether repeat or confirmation sampling is appropriate, and use an alternative water source if public-health guidance recommends it. Treatment equipment must match the contaminant and be maintained; a generic filter does not remove every hazard.

MAS offers property-specific water testing and can coordinate a sampling plan with the decision you need to make.

Primary resources

• EPA: Private Drinking Water Wells
• Florida DEP: Private Well Water Sampling
• Florida Department of Health: Private Wells