Hi; I am looking for info regarding storing of rain water in the winter. We have a 55 gal of rail water in our basement to us for watering the house plants in the winter, but as of late there has been a white scum on top of the water. I take a paper towel and skim it off. Can anyone tell me how to get rid of this or what is causing it to form and will is hurt the plants? 

You probably ought to throw it away. I do not think you can just let stagnant water sit like that and not have something grow in it. You could probably put some clorox in it to sterlize it, but that will probably kill your plants.

You could take a sample to get it tested. I don't think its too expensive. Next year I'd wash the barrel out with a bleach solution before you start saving the water again. Give it a good scrubbing! How about getting an aquarium or pond pump to aerate the water. Maybe that would keep the gunk from forming. I wonder if you could do that right now. Skim off the yuck and get the water moving with the pump.

Meri in MN zone 3b