Its raining....rain and ...rain

At least for me, now that I'm harvesting rainwater, any water that gets away is a tragedy. Today's rain quickly filled my 35 gallon water barrel, so then I diverted the flow into a 10 gallon storage tub which filled and then I put another there. This is only from gathering the rain from one side of one roof (I have two roofs). It occurs to me that during a rainstorm I could easily gather several hundred gallons of water from my entire roof. Given that we do have dry spells in Maine that can last a week or two, having 200-400 gallons of water would be a real benefit if we're trying develop a sustainable urban homestead.