· by Michael Blair, Nashville's Water Filtration
Water treatment equipment is often sold on the strength of a demonstration rather than a test, and the demonstration is designed to sell. A real test answers two questions: is there anything in the water that matters for health, and what is in it that affects taste, fixtures and appliances. The answers are different on city water and on a well, and so is the test.
On city water
Metro Water Services publishes an annual water quality report that covers what leaves the treatment plant, and by the standards it is tested against, Nashville water is reliably within limits. What that report cannot cover is what happens between the main and your tap: the service line, the house plumbing and the fixtures. Lead from older solder and fixtures, copper from corrosion, and anything the water picks up standing in the pipes overnight are house-specific.
A city water household that wants to test should test at the tap after the water has stood for several hours, for lead and copper, and separately for hardness, chlorine and total dissolved solids to size any treatment for taste and scale. The hardness figure is what matters for a softener decision, and it is a number, not an impression.
Who is responsible for testing a private well?
Nobody tests a private well except the owner. The baseline for any well in Middle Tennessee is bacteria, coliform and E. coli, and nitrates, which are the tests that concern health directly. Our limestone geology adds hardness, often very high, and iron, manganese and sometimes sulfur, which are the tests that concern the fixtures and the smell. A well near agriculture or an old fuel tank has its own additions.
Bacteria should be tested annually and after any flooding, repair or change in taste. The full mineral panel is needed once to design treatment and again if something changes. Test in the wet season and the dry season if the water seems to vary, because shallow wells in karst ground do.
- Well, annually: total coliform, E. coli, nitrate
- Well, for treatment design: hardness, iron, manganese, pH, TDS, sulfide
- City, at the tap: lead, copper, hardness, chlorine
- Either, if there is a reason: pesticides, VOCs, radon, arsenic
Strips, kits and labs
Test strips and the free in-home tests offered by equipment dealers measure hardness, chlorine and pH reasonably and little else with any accuracy. They cannot detect bacteria, lead or nitrates at the levels that matter. A dealer test that turns the water an alarming color is a demonstration of precipitation, not a measurement of anything harmful.
A certified laboratory test is the only one that answers the health questions. Tennessee maintains a list of certified drinking water labs, and county health departments can point to them. The lab supplies bottles with instructions on how to collect the sample, and the collection method matters as much as the lab, particularly for bacteria and for lead.
How do you read a water test report?
A lab report lists each parameter, the result, and the standard it is compared to, usually the federal maximum contaminant level or a secondary standard for taste and appearance. Anything above a health-based limit needs treatment or a different source. Anything above a secondary standard is a nuisance, and whether to treat it is a preference.
Take the report, not the dealer summary of it, to the conversation about equipment. A softener sized from a real hardness number, a filter chosen for the actual iron level, and a disinfection system installed because coliform was found, are purchases that solve the problem. Equipment bought without the test often solves a different one.
FAQ
Should You Test Your Water, and For What — questions
Can my own pipes affect Nashville tap water?
The water leaving the treatment plant meets the standards it is tested against, and the annual report is public. What the report cannot tell you is the condition of your own service line and plumbing. A tap test for lead and copper, on a first-draw sample after the water has stood, answers that.
How often should a well be tested?
Bacteria and nitrate every year, and after any flooding, work on the well or change in taste or smell. A full mineral panel once, to design treatment, and again if the water changes. Shallow wells in limestone country can vary between wet and dry seasons.
Are home water test kits accurate?
For hardness, chlorine and pH, roughly. For bacteria, lead, nitrate and anything that matters for health, no. Those need a certified laboratory, which supplies the sample bottles and reports each result against the applicable standard.
How do I get my water tested?
Use a certified laboratory. Tennessee keeps a list of certified drinking water labs, and your county health department can point you to one. The lab sends sample bottles with collection instructions, and following them closely matters as much as the lab you choose, especially for bacteria and lead samples.