Testing well water around Knoxville

Tennessee doesn't require homeowners to test a private well. That leaves it up to you, and in limestone country it's worth doing. This page covers when to test, what to ask the lab for, and where people around Knoxville get it done.

Why East Tennessee wells deserve a test

The USGS notes that where the soil over the carbonate rock is thin, Valley and Ridge aquifers are easily contaminated, because the network of fractures and dissolved openings lets water move quickly. It names landfills, underground storage tanks and septic systems as sources that can affect groundwater quality. TDEC's setback rules reflect the same concern: a new well must sit at least 50 feet from a septic tank or drain field, 100 feet from animal pens, and away from flooding. TDEC also asks owners to keep pesticides, gasoline, paint thinner and similar chemicals at least 20 feet from the wellhead.

How often to test

• Every year for bacteria. TDEC strongly recommends annual bacteria testing of private water supplies. EPA's list for the yearly test adds nitrates, total dissolved solids and pH.
• After pump or well work. EPA says to test right away when any part of the well system is repaired or replaced. TDEC requires installers to disinfect the well after service; test once that chlorine has been flushed out.
• After flooding, digging or new construction nearby. Both are on EPA's list of reasons to test immediately.
• When the water changes. New smell, color, taste or cloudiness.

What the water is telling you

That table follows EPA's well-owner guidance. Hard water should be expected: the USGS describes groundwater in these aquifers as hard calcium magnesium bicarbonate water. TDEC lists bacteria, iron and iron bacteria, sulfur odor, hardness and sediment as common Tennessee well water problems, all of which depend on the local rock.

Where to get it tested

• Knox County: the Knox County Health Department tests well water for total and fecal coliform bacteria. Call 865-215-5200, ext. 1, to schedule.
• Anywhere in the state: TDEC's Laboratory Certification Program publishes the list of private labs certified for drinking water, linked from its well water page. Use a certified lab for anything beyond bacteria.
• Elsewhere in the ring: EPA suggests asking your local health department, which may offer private well testing.

If bacteria show up

TDEC's advice is to disinfect the well and retest. Its method: one gallon of household bleach for every 50 feet of well depth, run each faucet until you smell chlorine, let it sit at least 12 hours, then run water until the smell is gone, keeping that chlorinated water out of the septic system. If bacteria keep coming back, TDEC says permanent treatment such as a chlorinator or ultraviolet light may be needed. TDEC also notes that a casing cut down near the ground leaves a well more open to surface water and bacteria, and that the casing should be sealed with a proper cap, so have a licensed installer look over the wellhead. In Tennessee, treatment equipment installers are licensed by TDEC too.

Buying a house on a well

TDEC says Tennessee has no testing requirement for private wells at sale. If your lender wants a test, ask them exactly which items they need, then take that list to a certified lab. While you're at it, find the well's driller's report and have a licensed installer look over the pump and tank.

Good questions

Does Knox County test well water?

Yes. The Knox County Health Department tests well water for total and fecal coliform bacteria; call 865-215-5200, ext. 1.

How often should I test my well?

TDEC strongly recommends a bacteria test every year. EPA adds nitrates, total dissolved solids and pH to the yearly list, and says to test right away after any repair or replacement of well parts.

Is clear water safe water?

Not necessarily. Bacteria and nitrate have no color, taste or smell, which is why the yearly test matters.