Gosh, I just let my water sit in the barrel until I use it. Not that it's had a chance to sit very long this season! But in the good old days when used to rain once in a while, water would stay in the rain barrel for months without mine worrying about it (except to put in a piece of mosquito dunk once in a while). I've never had a problem using "old" water.

---Margaret

As long as there is no organic matter in the water, it will not become stagnant. Keeping it covered (i.e., dark) will prevent algae growth, as well as keep out any organic matter (twigs, leaves, insects, etc.) that might decompose.

Thanks for all your replies. I, too, wondered about the organic matter coming off the roof, as I've seen quite a few leaf particles floating in it. I guess we'd better use it soon but they're predicting rain again! Go figure!

Hmm... why does it matter whether water is "stagnant" or not for watering plants? Do they care? Isn't the soil already full of bacteria and fungus and organisms? Why would it matter if there's more in the water? Aren't they simply going to be broken down in the soil? Actually, our observation is that standing water quickly forms a rather interesting and healthy little ecosystem, full of daphnia and other small organisms. This happens particularly quickly where the trough gets some sunshine. (You may not want to drink this water, but that does not make it "unhealthy" water in any natural sense!) A water trough provides a great source of live food for pond fish. And, providing that there are an appropriate number of fish in the container and that the amount of organic material does not overwhelm the system's ability to use it up (i.e. the fish are not overfed, for example), a balanced system is maintained with filtration or aeration. Sounds like a lot of worrying over nothing really. Lori

Oops, typo - meant to say "withOUT filtration or aeration"... Hope that makes more sense. Lori

IF your rain water grows algae, thats great. I have found that algae and other water plant are great for soil amendment and decompose extremely fast. If you don;t want the algae, just go to the pet store and buy a couple sucker fish. If you fish, you can catch one at the river(with moss or algae as bait). Hope this helps, Josh

Why hasn't anyone mentioned what folks on farms do for their watering tanks (and rain barrels) put a goldfish in it.

You can buy cheap goldfish (like the kind used for feeding snakes, etc..) at the aquarium store. Nothing fancy.

They are supposed to be hardy and you might put it in a bowl for the coldest months inside and feed it fish food.

Okay, first post.
Well as I understood it as long as you have the water moving it will not become stagnated for rain barrels(just rain barrels/tanks?).
So water flowing in and water flowing out moves the water.
And from reading one of these forums, algea is safe for the garden.
Keep it covered so leaves and mozzy's don't get in.

Same here - my query to consensus on how people keep their collected water from stagnating..

My first note, Dearest Lori, is that stagnated water is an efficient breeding ground for mosquitoes -- a taboo for anyone living in Ontario (anywhere, for that matter,) as our gov't spends a LOT of $$ on regular advertisements to dump standing water and for testing those pesky suckers for the West Nile virus.

And who wants to expose their skin, prized and / or edible plants to stinking and egg-infested water anyway? (I prefer the pail-inside-a-pail wick hydroponic gardening for my tomatoes, so the only way for hatched larvae to escape is up - through the lush growing medium)

So, are we left with few options than to run expensive wire to our reservoirs to run pumps, bubblers and / or UV/O3 generators?

Just what do all those 1000s of remote farmers use to eliminate stagnation in their reservoirs is my question?

From what I have heard, chlorine evaporates fairly quickly. I would think that if you timed your water use between chlorine applications, all would be well.

I don't know about stagnant water. People make compost tea to water their plants. I have not had much trouble with my new rain barrels. Going on three years now.

Hard for mosquitoes to get in.

Click the link below to see my rain barrels.

Here is a link that might be useful: My rain barrels

Stagnant water doesn't sound like a good idea. How about fine netting over the lid areas? that way mosquitos don't get in. What if the goldfish get sucked out? sounds kind'a cruel to leave fish in the barrel, what if they die? (Just from a health and moral standpoint, it's not like we'll know about it until it comes out the bottom, then who knows how long it's been dead for?!)

How about resting air stones in the barrels? that way you leave the lid (should you decide not to put a fine net/filter over the lid neck) partially open like a pressure cooker, which will cause it to release air slowly and you chuck maybe, 2 stones a week into the bottom, 8 stones a month, that's not even $5 and finally you'll have aerated, non-mucky water? Just an idea
No, i haven't tried it myself :D