Add 50ml un-perfumed ...

Add 50ml un-perfumed household bleach per 100 users per day will give about 3mg/l chlorine dose. If this results in a too-strong chlorine taste, reduce amount but do not dose less than 25ml per 100 users per day. Assumptions - 25 l/person per day, and bleach is at a concentration of 15% available chlorine.  Of course all contributions below are valid, but this is a simple calculation for health workers which should be adequate for most situations.