What is the minimum chlorine concentration required to disinfect sand and gravel used in filter pack wells?

The minimum chlorine concentration required to effectively disinfect sand and gravel used in filter pack wells is 50 parts per million. This concentration is established to ensure the effective reduction of harmful microorganisms and pathogens that could compromise the safety of the water supply.

When disinfecting materials that will be in contact with water, such as sand and gravel in filter packs, it's crucial to use a sufficient concentration of chlorine to ensure thorough disinfection. A concentration of 50 parts per million is recognized in several industry guidelines as the threshold necessary to achieve a robust level of disinfection, making it effective against a wide range of bacteria and viruses.

Using lower concentrations may not achieve the necessary level of disinfection, potentially leaving harmful organisms in the materials. Conversely, higher concentrations may be unnecessary and could lead to excessive chlorine levels in the resultant water supply, which could have adverse health effects or result in unpleasant taste or odor.

So, the choice of 50 parts per million aligns with standard practices in water treatment and disinfection, ensuring safe and compliant use of sand and gravel in well construction.