Todd - The American Red Cross website states 16 drops of chlorine per gallon -- meaning 4 drops per liter or quart of water.

However, the EPA website shows a chart with different dosage for different kinds of bleach. Chlorox, for example -- has 5-6% chlorine -- so only 1-2 drops per liter or quart are needed.

For me, I'll stick with 4 drops of Chlorox -- for two reasons:

1. A stronger formula will be more effective in treating viruses and bacteria -- as well as the smaller sized protozoa/cysts. This way, the filter only needs to block out the bigger sized protozoa/cysts.

2. The filter's carbon element will remove any strong chlorine taste -- so no harm in using the stronger "Red Cross dosage".