Shock treatment is also recommended if your groundwater supply (a dug or drilled well) has been polluted by bacterial contaminants. Contamination can result from the construction process, faulty construction, or as a result of a maintenance procedure. Shock treatment is also somewhat effective against iron bacteria or sulphate-reducing bacteria.

In general, shock treatment means producing a cholrine concentration of more than 300 ppm (Parts per million).

The general procedure for shock treatment is as follows:

From personal experience, you should not skimp on any step. If you do it wrong, your system will not be cleaned, and you will be painfully forced to repeat the process. After 10 days, get a good bacteriological analysis to see if you were successful. Repeat several days later just to be sure.