Anyone use rainwater?

yeah, don't get it off the roof!!! That stuff is nasty! if you have tin roofing it can put toxic amounts of heavy metals in your tank; if it is cedar, it can poison your fish with the chemicals from the wood; and if they are tar shingles they will kill your fish if any tar reside is put in your tank! the stuff you may collect from the garden, just in the open air is fine, but I have heard more than a few pretty scary stories about what it has done to tanks when it has been collected off of roofs. You may also want to be careful if you are living in a residential or urban area of a large city, because of the large amounts of pollution in the air that can have harmful, long term affects on your fish.

You will never know what is washing out of the atmosphere that you can't test. I would not use it myself, but if I did I wouldn't get the first shower or collect from a little sprinkle.

I would wait until there had been a hard steady downpoor for a while and then start collecting. I would hope that the first part of a hard steady rain would clear the air of toxins so the water would be better then.

Still, you wouldn't know what water soluable stuff evaporated with the water to start with.

I have used it for years w/o any problems from asphalt shingle roofs(let it rain good for awhile to rinse all the dust and debris off) and rubber roofs.

I am not downwind of any industry so low risk of those kind of pollutants. If you wanted to be real safe, you could run a canister filter on it with a polyfilter but I do not bother myself.

i'd have to say that its probably not a wise place to get water from

I looked into this and it is a very risky method because you have no consistency or guarantee with the water. Just because the air in your hometown is clean doesn't mean the rain is clean because it depends where the clouds were formed as well as their path and what they picked up along the way. then there's the method you're collecting it. I couldn't come up with a safe method of collecting a large amount of water without spending more money than it's worth. I think the r/o method is the safest because you get the same water every time. Unless you are a chemist and can test every batch of collected water for pollution, I wouldn't chance it. Kyle

ive also noticed that here in Peterborough we have had a lot of "dirty" rain which could be a suggestion that the rain water has some chemicals in it aswell.

You never know what you are getting in the water.
I had some problems after a very bad peice of advice from a LFS (I no longer use) that pond water from my stablished pond would be ideal for use in my tank, needless to say its choke full of parasites and allsorts of nasties, I havent used it since the guys/gals on here and a decent LFS advised against it and my fish look happier for it

Hows the tank Jamjarjames???