(It is a food grade barrel with a layer of latex paint inside). Most unfortunate. The paint itself when dried is not necessarily harmful but could get ugly and clog your hose/drain system. Sometimes paint will peel off in a few big sheets and sometimes adheres quite well to plastic. No easy way to remove it. Are they big pickle barrels? I got mine from a Deli. Is the paint completely dried? Sometimes a thicker layer might be in the bottom and skinned over leaving some wet paint under the skin...sort of a wet puddle. Dig into the bottom and see if that occurred. Sometimes that can be grabbed with a sharp object...a screw driver or other. May pull out in a big sheet. Might just be more trouble that it is worth...

So I did a search and found an interesting study on collected rain water quality. Here's the link (hope it works here): http://www.harvestingrainwater.com/wp-content/uploads/2010/01/Effect-of-Roof-Material-on-Water-Quality-for-Rainwater-Harvesting-Systems.pdf In short, metal roofs seem the best in terms of low contamination, but none are really that bad as far as irrigation water is concerned. There are some studies which point to asphalt shingles as being good in terms of PAH (organic hydrocarbon) contamination. But there are conflicting conclusions on that. http://www.thecenterforrainwaterharvesting.org/2_roof_gutters3.htm What I would like to see studied is contamination levels on more modern roofing materials, such as the factory baked on painted metal roofs (standard fair for metal barns and roofs today). And some studies in an area with neutral rain water (the Texas study had fairly acidic rain). I have heard that the factory painted metal roof material was tested as the cleanest of the current roof materials, but I have not seen the tests that bear that out. In general though, it seems that using collected water to water a garden or orchard is likely safe, as long as you are not in an area of high pollution, and you don't have an unusual roof (like lead coated copper). If you have zinc surfaces that the water travels over (roof, gutters, etc) then high zinc levels might be a concern over the long run. Or if your roof/gutters have solder joints (lead) then that may be a concern. The more acidic your rain water is, the more concern about picking up heavy metals. Anyway, that's my take. You can find quite a bit of stuff to read on this topic with a quick internet search, so do your own research. Disclaimer, I am not a doctor nor a chemist and do not play either of them on TV.

it is BS. just like all the folks that say not to drink from a hose because you get lead poisoning. YES there are trace amounts, but NO they are no where near enough to ever harm you. heck, the algae that grows in teh barrel is worse for you than what is in the runoff of the roof. don't drink straight from the barrel adn you will be fine.

Sulfur (rotten egg) smell occurs in my rain barrel from time to time, but it is not from sulfur storage or dead animals...it is simply the anaerobic (without oxygen) breakdown of organic matter in the water. If there were leaves or other similar material in your gutters then your rain barrel probably received a load of organics...evident in the yellowish tinge you saw. The breakdown of the organics uses oxygen (aerobic). When all the oxygen is depleted, the breakdown of the organics will occur by a different mechanism. The time it takes will depend on the amount of organic matter, temperature, size of the rain barrel etc. One of the possible byproducts of this is hydrogen sulfide gas. The same thing can be smelled around stagnant swamp water (due to higher organic load and no aeration). Some of the byproducts of anaerobic respiration aren't ideal for your plants, but at levels likely to be found in a rain barrel, I have never worried about it myself and haven't had any problems. The way to avoid this altogether is make sure your barrel and gutters are clean...something not easy to keep on top of all the time. If you have a way of aerating your rain barrel, then you can avoid using the bleach. Otherwise, I wouldn't worry too much about it.