Is rinsing diluted H202 in water also good enough?
The H202 should be 3% and the reason for the water pik is to get in all crevasses, in, around, and between the teeth. I have read that it even gets 6mm below the gum line. The idea is to get all food particles removed every day. They cause cavities, and cavities can turn into other bad things.
The H202 should be made from 35% H202, not the kind you buy at the drug store that has fillers and other ingredients.