Chemicals added to a groundwater supply should be added:

The addition of chemicals to a groundwater supply should take place after the check valve. This is because the primary function of a check valve is to prevent backflow, ensuring that water flows in one direction. By introducing chemicals after the check valve, they can be mixed properly with the water as it moves towards treatment facilities or distribution systems.

Adding chemicals before the check valve can create several issues, such as potential contamination of the water supply if there’s any backflow. Additionally, treatment processes that occur downstream depend on the chemicals being effectively distributed within the water, which is facilitated by adding them after the check valve.

At the well head is typically where the water is first drawn, making it an inappropriate point for chemical addition, as it might not guarantee effective distribution and could lead to complications in system management. Adding them in any sequence could lead to inconsistent treatment and possible operational hazards, disrupting the intended treatment pathway and efficiency.

Thus, the process of adding chemicals after the check valve is a crucial practice in ensuring the safety and efficiency of water treatment operations.