I thought I would pass this experience along. I have been growing herbs and vegetables in elevated tables and have noticed that when the rain waters the tables, the plants seem to thrive noticeably more. During dry weeks I have to water them via city water, that's when I started noticing the growth slowing. I suspect it the chlorine that might be stunting the growth. I installed 2 of the 55 drum rain barrels and now exclusively water using that, man what a difference!

I suspect but have no actual knowledge that rain forming in the upper atmosphere that is nitrogen rich allows the rain to absorb small amounts that are carried down with it and it is one of the reasons plants react so much better. I've heard from plant gurus that snow carries even more nitrogen with it. Just a idea I've came up with after listening to radio gardeners and such.

I think you pose an interesting idea. I started researching a bit and came across this article:webpage

I think hands down rain water is the best!

Yeah I think for many reasons combined plants always respond alot more and also more favorably to actual precipitation from clouds. my feeling has always been that the reason was so many factors combined but I can't test much with only access to city water and rain. Someone with a pond that could be used for irrigation could do a test with rain, pond irrigation, and municipal irrigation to compare.

Did you test the pH of the city water? When I lived in Michigan I had a similar situation. My indoor plants were not doing so well with the brita filtered tap water. When I checked the pH it was around high 8s to 9! When I later checked rainwater it was right at 7, maybe slightly acidic, 6.5 ish. So needless to say I never gave my plants tap water again and realized much better yields.

But as far as chlorine, isn't that supposed to fly off rather quickly after water is dispensed from the tap? A friend of mine here in CA had no choice but to use tap water and he'd fill large containers to let them sit for awhile (overnight?) before giving to plants to give the chlorine a chance to fly.

Thank everyone for the great feedback!

I had not thought to check the pH of the rain water vs the city water. I live in North Texas and the water is very hard, so that kinda makes sense. I actually have litmus paper at home and will check tonight.

Jarrod Pearson wrote:I had not thought to check the pH of the rain water vs the city water. I live in North Texas and the water is very hard, so that kinda makes sense. I actually have litmus paper at home and will check tonight.

Another thought regarding the chlorine content of the water:

Maybe it's not affecting the plants directly, but indirectly by killing off the myriad little critters that make up the soil food web.

If tap water has enough chlorine in it to negatively affect fish in a tank if not given enough time to gas off, surely it would hit the microbial life in the soil pretty hard as well.