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"Safe" Metal Roof and Tank for Water Catchment  RSS feed

 
Robbie Asay
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When I build my little house I'm going with a gambrel(barn) roof for two reasons; eventually mounting solar panels on the upper section and also a bigger roof for water catchment.

I've read a lot about paint and other toxic stuff that are on these panels so what are the safer ones to use?

Along the same lines I'm trying to reduce the amount of substances I'm exposed to and although I won't get away from everything I'm trading off certain things for others.  For example; I'll be using PEX for the indoor plumbing but would like a safer cistern.  Any suggestions on these?

 
wayne fajkus
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Im good with galv roofing. Prob stay away from painted if possible.


My take is this. The rainwater is purer and has less chemicals in it over the stuff pumped in from a municipality.

Look at it in this prospective:

Water will be on your roof for 5 to 10 seconds. It will be in your pipes for days. It will be in the storage tank for months.

So if worried about absorbing glick, tank is first priority followed by pipes, then roof. Pipes would be hardest to replace down the road.

I'm not advocating an asphalt shingle roof, I'm just saying the roof is not the biggest concern for me overall.


 
wayne fajkus
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I saw a beauty of a storage tank at an auction recently. Probably 2,000 gallon tank made of stainless steel. It was for holding milk. I wish I had stuck around to try to purchase it. Tanks are so expensive. Prob $1500 for plastic 3,000 gallon.
 
Robbie Asay
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wayne fajkus wrote:Im good with galv roofing. Prob stay away from painted if possible.

I'm not advocating an asphalt shingle roof, I'm just saying the roof is not the biggest concern for me overall.


Okay, but it is my concern.  It's exposed to more harsh elements than pipes and tanks therefore it's more susceptible to leeching and flaking.

There were some painted ones that were special for water catchment but I don't remember what they were or what the coating was.  I don't know enough about them hence my researching and asking questions.  They'd have to be sturdy enough for the solar to be mounted or stuck on them in the future.


Wayne I would LOVE a stainless steel tank!
 
wayne fajkus
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I'm not aware of a specific rain roof material. I'd love to hear about it if you find it.
 
John Wolfram
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Well...if you're made of money, an authentic copper roof would be about as good as you can get considering that's what is used in many homes to deliver drinking water. In my case, I've got one of those painted steel roofs, and while I can't speak to what is happening on a microscopic level, seven years in it still looks as good as the day it was installed.
 
Su Ba
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Here in Hawaii, metal roofing for water catchment is common. By far the most common metal roofing is the type that is factory painted steel. An example of this can be seen on the website of my island's main supplier, HPM. It's the type of roof I have on my own house. When our roof was new, the water it collected was clear and smelled clean.

There is an approved paint for these roofs here, but I can tell you from experience that it takes several days to cure and harden, plus several rains where it is no longer obviously leeching off. When we painted our roof, we didn't collect the water for several rains, then diverted it to the orchard for several more rains before we were willing to use it for household use. We don't drink it. I don't know what sort of chemicals leeched out from that paint, but I wasn't happy about it. The next time our roof needs work, we plan to just replace it instead of painting it in order to avoid the chemicals. We'll use the old roofing for other projects.

As for tanks, we use round corrugated steel tanks with food grade plastic liners. Perhaps not as permaculture friendly as other systems, but the liners last decades when properly cared for. Our liners are 15 years old and in excellent condition. I have neighbors who have liners 30+ years old. Liners aren't necessary for all tank types. The old redwood tanks in my area don't necessarily have liners, but maintenance is a bit more tricky with them without liners.
 
Larisa Walk
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We've used a galvanized roof for rainwater catchment for over 30 years.  Our cistern tank(s) are stainless steel - we have a 2500 gallon milk truck tank buried for household water which keeps us supplied through our Minnesota winters.  We have a 300 gallon stainless steel bulk tank that feeds into the underground tank.  On this tank there is a screen and a standpipe overflow so that dust can settle out.  We use a carbon block filter in the house but in the past we didn't used to bother. We also have 3 above ground 1500 gallon ag tanks for irrigation water. You can see more about our system at http://geopathfinder.com/Rainwater-Harvesting.html.
 
Robbie Asay
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wayne fajkus wrote:I'm not aware of a specific rain roof material. I'd love to hear about it if you find it.


Found it!  It's Galvalume.  I may not have to use it though.  From the information from these sites I can use painted metal roofing if I use a "first flush diverter":

http://www.shared-source-initiative.com/biosand_filter/biosand.html
http://www.harvestingrainwater.com/wp-content/uploads/2010/01/Effect-of-Roof-Material-on-Water-Quality-for-Rainwater-Harvesting-Systems.pdf

I feel better now because when attaching the solar sealant and/or adhesive must be used around the entry points into the roof material.  Yeah I know, it sounds anal but in consideration of all the maladies we humans seem to get these days I'm trying my best to balance out toxic exposure with good eating and hopefully break even.  Howard Hughes I am not.
 
Robbie Asay
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Larisa Walk wrote:We've used a galvanized roof for rainwater catchment for over 30 years...


Thanks for that information!  I'm going to keep an eye out for a stainless steel tank in the future.  I really like how easy they would be to clean.
 
wayne fajkus
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When we reroofed to get rid of asphalt,  we used galvalume. Nice to know I did something right.
 
frank li
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Less glick. No caulk solution.

http://sunmodo.com/roof-attachment/

https://goo.gl/images/A3OSCU

A stainless steel roof to go with a milk vessel?$!

A good filter and pre-filter system.

If there is doubt about roofing materials safety, then reverse osmosis could be used. The same treatment given to remove contaminants found in rainwater should remove or reduce materials related to solar equipment and metal roofing.

The backing and wiring of pv systems are troublesome but should have minimum contact with water on a roof-mount. Wire gets wetter and will likely be polyethylene, but has flame retardant.

Aluminum, anti sieze or waterproof grease, epdm, anodizing coatings, and anti glare coatings are some things to expect but are probably not as troubling as rain or dust could be, especially if you have at least the rinser, pre filter and a carbon/ceramic or other finish.

Im with you guys on it not being asphalt, being the best start.






 
Larisa Walk
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Location: South of Winona, Minnesota
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Another important point to consider when collecting rainwater is timing.  Letting the roof rinse well first helps a lot (plus keeping the gutters clean - it helps to not have trees around the collecting roof).  And the time of year rain is collected means avoiding ag chemicals that are being applied during the growing season or that are getting kicked up in dust during harvest - collect before and after major farming activity (early spring and late fall here).  Large fires out west can contribute to haze in the midwest and probably add toxic particles to rain (nuclear accidents too).  More to think about than just the installation.  As for stainless steel roofs, the rain is only on the roof briefly, as stated in an earlier post.  Galvanized roofing and gutters may add minute amounts of zinc but not beyond what the body can utilize as a micro mineral.  I think the carbon filter would take out most of that if that's a concern.  Birds don't generally like hanging out on galvanized roofs so poo isn't a big problem, at least here.  The biggest concern is man-made pollution.  It's a sorry situation when rain is potentially contaminated, but still probably less so than most aquifers.
 
wayne fajkus
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I bought a filter for the water and ice in my fridge door. It's now being advertised as removing residual medicine from the water.  That really really set me back. Wow. Is that a real thing, or just scare tactics?
 
Stephen Touron
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A while ago, I was wondering about the same thing and I found this:

http://www.harvestingrainwater.com/wp-content/uploads/2010/01/Effect-of-Roof-Material-on-Water-Quality-for-Rainwater-Harvesting-Systems.pdf

They actually tested different roofing materials for a variety of chemicals. The first tests were small mock-ups but they later tested several full sized roofs.
 
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