Why your “clean” well can act weird after treatment (especially in Florida winter)
If your home has a private well, you’ve probably heard of shock chlorination. It’s a common way to disinfect a well after bacteria concerns, flooding, service work, or a home sitting vacant.
Here’s what surprises a lot of homeowners:
Shock chlorination can temporarily affect well performance — even if you don’t run the chlorinated water through the house plumbing.
Most of the time, nothing is “broken.” It’s simply the well reacting to a strong disinfectant doing its job.
What is shock chlorination?
Shock chlorination is when a higher-than-normal chlorine concentration is added to the well to kill microorganisms. It’s often done after:
- A positive bacteria test (Total Coliform or E. coli)
- Pump replacement or well repairs
- Flooding or heavy rain intrusion
- Long periods of low use or vacancy
Why it can affect pressure and water clarity
Chlorine doesn’t just kill bacteria — it also acts like a deep cleaner. That means it can loosen buildup inside the well and the system.
1) Sediment and biofilm get stirred up
Over time, wells can collect mineral deposits and bacterial slime (biofilm). Chlorine can break that loose and you may see:
- Cloudy water
- Gray/tan/light brown water
- Grit or sediment
2) Pressure can drop temporarily
That loosened debris can partially restrict flow at the pump intake or well screen, causing:
- Weak pressure
- Pressure surging
- Slow recovery
- Pump cycling more than expected
3) Minerals can show up more (staining/odor)
After shocking a well, it’s common to notice:
- Orange/brown tint (iron)
- Dark staining (manganese)
- Metallic taste or smell
4) Strong chlorine can be hard on components
If the mix is too strong or sits too long, it can be rough on older seals, gaskets, and rubber parts. Correct dosing and flushing matters.
Florida winter “dry season” can make this worse
In Northeast Florida, parts of winter can bring lower rainfall, which can mean lower groundwater levels. When the water table drops, wells may:
- Produce less water (lower yield)
- Pull more sediment
- Have more noticeable pressure swings
So if a well is shocked during a dry stretch, you might notice performance issues more than you would during a wet season.
What you might notice after shock treatment
These are common short-term symptoms:
- Cloudy or discolored water
- Sediment in water
- Strong chlorine smell
- Pressure changes or weak flow
In many cases, the well just needs time and proper flushing.
The key step: flush it properly
After shock chlorination, flushing helps:
- Remove leftover chlorine
- Purge loosened debris
- Stabilize water quality
Best practices:
- Flush until the chlorine odor is gone
- Continue until water runs clear and steady
Avoid running chlorinated water through filters/softeners unless you know it’s safe for that equipment
When to retest
Don’t retest too early — chlorine can interfere with results. After flushing and stabilization, most homeowners retest:
- Total Coliform and E. coli
- Nitrates/Nitrites
Optional: lead, pH, iron/manganese, and specialty panels like PFAS (by request)
Red flags that are not “normal”
Call a pro if you have:
- No water or major pressure loss that doesn’t improve
- Constant short-cycling
- Muddy/sandy water that won’t clear
- Repeated positive bacteria tests after treatment
That can point to a pump, pressure tank, or well yield issue — not just temporary shock effects.
How Bobcat Home Inspector can help
A well inspection is more than “water comes out, so it’s fine.” I can help with:
- Mechanical well inspection (pump/pressure system)
- Flow and pressure performance checks
- Certified water sampling sent to a lab
- Clear, actionable results without guesswork
If you’re buying a home with a private well or maintaining one in Northeast Florida, I’m happy to help you get real answers and peace of mind.