I have alkaline, mineral-rich water which does a number on my more acid-loving plants. For two years now I have had a rainbarrel in place and generally use it for watering my bananas, blue berries, transplants and seedlings. But there times during particularly long dry spells when I need to run a sprinkler which hits the blueberries and other plants that just don't appreciate the alkalinity of the tap water.

There is nothing fancy about the barrel, just a simple gravity drain tap, but I keep wondering if there is a way to tap into the rainbarrel as an augmentation for the tap water when running the sprinkler. Something akin to the liquid-feed sprayers that allow the water to pass through and pull the liquid feed into the stream without allowing the water to refill the tank. The easiest thing I can think of is two backflow adapters attached to a 3-way junction so that rainwater doesn't flow into the main line and the tap water doesn't flow into the rain line, but I don't know if this will actually work to augment and neutralize the tap water enough to make it worth it. Any experienced input into such a setup/situation?