Cure for foul water?

I have a dozen water barrels around the house at each downspout and every time one of them is empty I wash it out with soap. You water has anerobic organisms thriving. Another thing you can do if you only have one barrel is to buy a cheap fish tank pump and attach an aerator to the end of the tube and keep the water aerated.

Rain water isn't as pure as we'd like to think, the droplets pick up dust as they fall. The roof is covered with dust, leaves and bird droppings that get washed down the gutter and into your tanks.

Watering the plants with it isn't going to hurt anything, and once the soil dries out a bit the smell will too. But if it bothers you, a few drops of chlorine bleach will temporarily stop the smell. Circulating the water will also work, such as using a cheap aquarium air pump.

-S

There are five jugs that I keep indoors due to sub-zero temps; I'm in an apartment-sized duplex with no electrical outlets where they are kept out of the way. The jugs are almost 2' tall but with openings 1.5" wide, which makes them difficult if not impossible to clean. Maybe if I swish some coarse sand around in them it'll loosen the residue on the bottoms. Well anyway, I'll always have organic matter in them because of a sick tree (which isn't mine to remove) that hangs over the gutters, constantly throwing its trash down in them. I was afraid of using household bleach because of "other stuff" that might be in it, so I was kinda leaning toward H2O2. Potassium permanganate would also help oxidate the water, but is expensive and messy. I just know I need to do something because every time I water the bigger plants in my son's room it stinks the whole room up.

I'd use household bleach. Not sure how much but I'd imagine a teaspoon full in what appears to be a 5 gal jug should do no harm. Google and see how much is recommended for purifying water in a canteen. If you can drink it, it will not harm plants. Frank