When I lived in San Jose, they'd let us "bank" any of our allotment that we didn't use and use it for credit in months where our usage was high. That was 30+ years ago and I don't remember most of the details now.Funny thing is I pay every month for 10,000 gallons of water whether I use that much or not. Summertime with watering the lawn and gardens I use about 11,000 gallons so I pay for the extra.