What chlorine concentration is used to disinfect a well according to the guideline?

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Multiple Choice

What chlorine concentration is used to disinfect a well according to the guideline?

Shock chlorination is used to disinfect a well, applying a high chlorine level to kill bacteria throughout the well and surrounding piping. The guideline calls for about 200 ppm of free chlorine because such a high concentration overcomes biofilms and deposits that protect microbes, ensuring thorough disinfection and enough contact time to inactivate organisms. After mixing to this level, let it sit for a recommended period (often 12–24 hours), then flush the system and test to confirm the chlorine residual and that the water is microbiologically safe. Lower levels like 2 ppm or 0.2 ppm are typical for ongoing disinfection in treated water, not for shock disinfection, and 20 ppm generally isn’t sufficient to reliably disinfect a well.

Shock chlorination is used to disinfect a well, applying a high chlorine level to kill bacteria throughout the well and surrounding piping. The guideline calls for about 200 ppm of free chlorine because such a high concentration overcomes biofilms and deposits that protect microbes, ensuring thorough disinfection and enough contact time to inactivate organisms. After mixing to this level, let it sit for a recommended period (often 12–24 hours), then flush the system and test to confirm the chlorine residual and that the water is microbiologically safe. Lower levels like 2 ppm or 0.2 ppm are typical for ongoing disinfection in treated water, not for shock disinfection, and 20 ppm generally isn’t sufficient to reliably disinfect a well.

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