Your well flooded. What to do.

A private well that has been under floodwater is presumed contaminated until a test says otherwise. That is not caution, it is what the testing after our last two hurricanes actually found.

What the state advises first

North Carolina health officials are direct about this: they recommend calling your county health department or a licensed well contractor to shock chlorinate a flooded well, rather than doing it yourself. The reason given is practical rather than bureaucratic. A contractor has access to more effective products than household bleach, and has the equipment and the experience that a well owner does not.

That matters more than it sounds. A disinfection that does not reach the whole well and the whole plumbing run leaves you with water that smells clean and is not.

Why this county in particular

Robeson County was among the hardest hit areas in Hurricane Florence. Researchers from UNC and Virginia Tech sampled 62 private wells here afterwards and found total coliform in more than a quarter of them. Across the state, of the wells submitted for free testing after that storm, roughly 15 percent came back positive for E. coli or fecal coliform.

The reason is not mysterious. When the water comes up it carries whatever it crosses: overflowing septic systems, sewage from public utilities, and in this part of the state the contents of hog waste lagoons, 33 of which breached during Florence. Matthew in 2016, Florence in 2018, and further state guidance issued for flooded wells since. This is a recurring problem here, not a freak one.

Signs your well was affected

• Floodwater reached or covered the well head, or stood in the yard around it.
• The water is cloudy, discoloured, or tastes or smells different.
• The pump lost power during the flooding, or has been running oddly since.
• Sediment or grit is coming through the taps.

Any one of these is a reason to test. None of them is reliable on its own: contaminated well water very often looks, smells and tastes completely normal, which is exactly why testing exists and why "it seems fine" is not an answer.

Shock chlorination, if you are doing it yourself

This is the outline of what North Carolina health guidance describes. Get the full instructions from your county health department, and read the warning underneath it before you start.

1. Use the right bleach. Unscented household liquid bleach with no cleaners added, around 5.25 percent chlorine, less than six months old. Bleach loses strength on the shelf, and old bleach is the common reason a disinfection does not take.
2. Get it through the whole system. Turn on each tap in the house one at a time, hot and cold, including showers and toilets, and run each until you can smell chlorine.
3. Leave it. Minimum eight hours, or overnight. Nobody drinks or bathes in that water during this time.
4. Flush it out. Run an outside garden hose until the chlorine smell is gone, keeping the discharge away from your septic system, your planting and any pond, ditch or creek.
5. Then test. Disinfecting is not proof. The test is the proof, and it comes after.

Getting it tested

Testing for a private well in Robeson County goes through county environmental health. After a declared storm, the state has previously offered free testing to well owners in affected counties, so it is worth asking whether that is running before you pay for it.

What this costs

Disinfection by a contractor is a small job. A pump that has been submerged and needs replacing is not. What well work costs in this county sets out the ranges honestly, including the ones nobody enjoys.

Sources: NC Department of Health and Human Services guidance on keeping wells safe before and after a flood; UNC and Virginia Tech sampling of private wells in Robeson County following Hurricane Florence; NC Division of Public Health post-Florence well testing results.