A Private Well Owner's Testing Checklist for Northwest Arkansas

If you are on a private well, you are your own water utility. There is no monitoring, no annual report, and no regulatory backstop. Whatever is in your water is yours to find out about.

That sounds ominous. In practice most Northwest Arkansas wells produce perfectly good water, and many need little or no treatment. But you only know that by looking.

The annual tests

Total coliform bacteria and E. coli

Test annually, without exception, and additionally after any flooding, any work on the well, and any change in taste, smell or appearance.

Total coliform bacteria are common in soil and are not usually harmful themselves. A positive result means a pathway exists by which surface material is reaching your water — and if that pathway is open, something more harmful could use it. A positive E. coli result indicates faecal contamination and is more serious.

This matters more in the Ozarks than in many places. Karst terrain allows water to move quickly through fractured limestone with less natural filtration than a sandy aquifer provides.

Nitrate

Test annually. Test urgently if there is an infant in the household, if someone is pregnant, or if you use well water to prepare formula.

Nitrate is invisible, tasteless and odourless. The federal standard of 10 mg/L as nitrogen exists specifically to protect infants, who are vulnerable to methaemoglobinaemia. In a region with substantial agricultural activity and a lot of septic systems, this is not a theoretical test.

One critical point: boiling makes nitrate worse. Water evaporates and nitrate does not, so boiling concentrates it. This is the opposite of the correct response to bacteria, which is exactly why knowing which problem you have matters.

The baseline tests

Hardness, iron, manganese and pH

Test at baseline and whenever something changes. These are the workhorses of system design: hardness sizes a softener, iron and manganese decide whether you need an oxidising filter and which medium, and pH determines whether that medium will work at all.

pH deserves particular attention. Several oxidising media only function above a specific pH, and manganese generally needs a higher pH than iron. Installing an iron filter into water below its working range is the most common reason these systems disappoint, and it is entirely avoidable with an inexpensive measurement.

Arsenic

Test once as a baseline, and again if the well is deepened or reworked, or if nearby wells are found to have it.

Arsenic comes from geology, which changes slowly, so it does not need annual attention. But it is colourless, tasteless and odourless, and concentrations vary substantially between wells even over short distances. If it is detected, ask for speciation — whether it is arsenic III or arsenic V — because most treatment technologies handle arsenic V far better, and arsenic III generally needs oxidising first.

Lead and copper

Test once, and again after any plumbing work. Higher priority in a home built before 1986, when lead solder was still permitted.

Use paired sampling: a first-draw sample after the water has sat in your plumbing at least six hours, and a flushed sample afterwards. If first-draw is much higher, the metal is coming from your plumbing rather than your well — and that points at a completely different solution.

Test when something changes

Beyond the schedule, test whenever:

• The taste, smell, colour or clarity changes
• The well floods or the area around it does
• Any work is done on the well, pump or pressure tank
• A nearby well tests positive for something
• You buy the property — before closing rather than after
• Someone in the household becomes pregnant, or an infant arrives
• There is unexplained gastrointestinal illness in the household

Look at the wellhead too

Testing tells you what is in the water. A five-minute look at the wellhead often tells you how it got there.

• Is the well cap intact, sealed and in place?
• Is the casing undamaged and extending above grade?
• Does the ground slope away from the casing, or does water pool against it?
• How far is the nearest septic system, livestock area or fuel storage?
• Has anything changed nearby — new construction, land clearing, a new septic field?

Where a test comes back positive for bacteria, the pathway is often visible at the surface. Fixing that is a better use of money than permanently disinfecting water that should not have been contaminated in the first place.

Where to get testing done

The Arkansas Department of Health and your county extension office can point you to certified laboratories, and you are entitled to approach one directly without going through any water treatment company. We think that is a perfectly reasonable thing to do, and we would rather you tested with someone than skipped it because a water company was involved.