what is water line germ removal procedure
Common 5.25% hypochlorite "liquid laundry bleach" (unscented) is the chlorine source that is typically used. It not used (and actually not even most effective) at full strength, but rather added to water in the system to achieve a certain concentration for a certain contact period.

Sources appear to vary between suggesting 10, 50 or 200 ppm chlorine concentration for a "shock treatment." Contact time suggestions range from 2-24 hours.

52.5 ppm would be 1 ml (5.25%) bleach per liter of water. 

Do not exceed 200 ppm or 24 hours. More is not better beyond those, and there is debate regarding even going that high or for that long.

Flush the system throughly after disinfecting with chlorine bleach - there should be no remaining smell of chlorine.