They drink the strongest available on the machine at 9.5, but they worked up to that from 8.0. They clean the machine twice a month and they test the pH once a month to make sure everything is working as they should. The machine is attached to their kitchen sink faucet, so anytime they use the faucet they are using alkaline water, unless they want acidic water in which case they switch the machine to about 4.0 (they use the acidic water to clean their faces, clean kitchen countertops, etc). For them first they noticed decreased incontinence in about 2 weeks. The arthritis symptoms subsided within 3 months. Their doctors say it's all in their heads, but I'm like who cares how it is working IT IS working. They have been drinking this water for about 5 months now, so I'm excited to see what the long term benefits are.