Alex, I don't have a lot of data but on both tar shingle and clay tile roofs, I have seen first hand tds exceeding 100ppm after a second flush. Much higher on first flush. I think it really depends a lot on the age of the roof material, the weather, and how long and how much dust and air particles have gathered and the volume of rain fall.
Generally, I want to collect and use all of the rain possible. But I divert anything 100ppm or higher to only be used after minimal filtering to ornamental plant use. In a pinch, I know I could filter, purify, and polish it enough for my AP but since the ornamentals do need water too, they get the dregs so to speak. Yes, my wife might argue that. :)
Anyway, I know the worries about roof materials. And we should be concerned and should NOT allow the particulate to accumulate. But our concern shouldn't end with tile, tar or asphalt materials. I believe in filtering and purifying as well as possible prior to use in our AP. AND in constantly removing a good portion of what does tend to accumulate with the use of weekly partial water changes and or replacement treatment. I also believe that more harm is done by, and there is more risk in using or relying on, chlorine and chloramines than roofing materials.
That's why I purify and polish with ozone, hard mountain river rock, a fodder growing stream and an active bog filter.
I try to keep our new water as pure as possible and still provide proper mineralization, pH, temperature, co2 and oxygen, balance. And I think it's easier by striving for as pristine of a stream entering the process to work with as possible. Without being completely engulfed about it. Leaving more time to focus on the actual bio activity in the tanks, channels, and beds.
Here is a link to a list of quite a few discussions where Rainwater was mentioned. The search feature in the upper right corner of all screens is useful in finding previous discussions.
Hope this helps.
Is there already a discussion going on about your rainwater collection? I'm curious to hear how you are doing it. I was thinking about collecting rainwater from the roof of the greenhouse. I would even build a "food grade" stand-alone dedicated collection device, if it would work well. I have a serious water problem.
No, I haven't done any testing on my rainwater.
I think some people would argue that you can safely collect rainwater from a polycarbonate greenhouse, but it never hurts to filter it. Since TDS stands for total dissolved solids, it would really be important what those dissolved solids are, not just that there are solids in the water. With tar based shingles, you can pick up all sorts of unwanted crap that doesn't belong in your system.
Alex, I am postulating a solution to my well problem pre-greenhouse. I had assumed the water would come off the large south leaning twin wall poly carb roof. I would also be willing to build something stand-alone if I needed. Alex, have you measured TDS in water off the shingle roof before and after your filtering? Even if you only ended up with 5ppm TDS, WHAT makes up that 5ppm???? Have you sent any in for testing?
Excellent info. Many thanks.
Hydro Clif said:
I work for a company that makes dehumidifiers. Over the years we have had this question come up many times. Some folks want to use the water to make drinking water, others want to use the water for gardens, and others for fish tanks. Recently I gathered water from 3 dehumidifiers and sent it to a labratory for extensive testing. The oldest unit was over 10 years old and had all original parts, the newest unit was brand new. Long story short, the water that we collected passed a well water test and was more than acceptable to be consumed by humans. The water was superior to tap water. In regard to heavy metals, most dehumidifiers use copper pipes, just like the water pipes that many homes utilize. These pipes are brazed together, not soldered, just like the water pipes in many homes. I can't talk for other brands specifically, but I can say that it is most likely that all dehumidifier create safe potable water.
Nitrate 0-.19 ppm
Aluminum 0-11.8 ppb* (*parts per billiion)
Copper 0-74.9 ppb*
Zinc 0-0 ppb*
All three units were under the limit for acceptable drinking levels of Bromate, Chlorite, Chloramine, Chlorine and
The published article will have more details and should come out in the March, April or May edition of Maximum Yield magazine.