Before returning an existing well to service, how much should it be chlorinated and for how long?

The recommended practice for chlorinating a well before returning it to service typically calls for achieving a chlorine concentration of 50 ppm (parts per million) and maintaining that level for at least 3 hours. Chlorination serves to disinfect the well, killing any harmful bacteria or pathogens that may have entered during maintenance or due to groundwater contamination.

Maintaining the chlorine at this concentration for the specified duration ensures effective disinfection, allowing enough contact time for the sodium hypochlorite or chlorine to act against microorganisms. After chlorination, it is common to flush the well to remove excess chlorine and any residual contaminants before resuming service.

In contrast, other options either increase the concentration beyond what is generally recommended or decrease the exposure time, which could result in inadequate disinfection and potential health risks if bacteria remain in the system.