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PVC for rooftop collection?  RSS feed

 
gustavo alcantar
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I'm working on a project in mexico desert where water is scarce so we have been designing a system to store as much water in the form of swales and expanding the existing pond, as well as building compost toilets, mulching trees, etc. While i was away from the project for 5 weeks the local guys decided to construct a rooftop system (without telling me - arrgh!) that uses pvc pipes/elbows/t's/glue for the whole length of the system. I've just arrived back here and am not sure if this will last in the longterm.

It doesnt appear to have sufficient slope and the pipes already look kinda wonky, sagging a little here n there, and they havent installed any first flush. I'm wondering if anybody has experience with doing a system like this? My concern is that PVC in the full hot desert sun will deteriorate rapidly, and that if there is sediment buildup in the pipes it may clog and be harder to clean than a standard gutter. Not to mention dioxins produced by PVC.

Most houses in this town already have thin metal/alum(?) pipes built into the rooftop that then spill directly out into the sidewalk. I thought this was a perfect scenario to simply cut the existing pipes down since they extnded out about 1 foot, and have the water drop into a standard gutter. Easy. Instead they completely removed the old cemented-in pipes and simply laid the pvc in its place with gaps underneath (which tells me water will leak away), attached to an immediate elbow, 3" or so of vertical pvc, a "t", then a 6-8 ft horiz PVC joined to another elbow/vert/t set, followed by another and another. Seems like a lot of room for failure.

This is supposed to be a local permie demo site but this is not the way i would have done it so it feels less exciting to demo it. Am i being too critical? I could add fotos (sorry dont have them yet)
 
Miles Flansburg
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Location: Zones 2-4 Wyoming and 4-5 Colorado
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Howdy Gustavo, welcome to permies. Ya I would think that PVC would not have been my choice either. Pictures always help .
 
Nick Simcheck
Posts: 57
Location: Southeast Michigan, USA
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PVC will become extremely brittle when subjected to UV rays for extended periods of time.

I'm willing to bet that in those conditions, regardless of pipe diameter a 5ft drop would break even schedule 40 after 2 years of exposure.


What are your other options? Obviously there are better materials available but we're not sure what is available to you, aside from tin which seems to be a good choice. (aluminum is bad for drinking water, research links it to alzheimer's decease)
 
Ken Peavey
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Location: FL
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As Nick said: PVC becomes brittle.
My experience says it will hold up for several years, but an impact (ball/stick/fist) will readily crack the pipe in time. Mexico has more direct sun than my experience, so a couple years is probably about right.

There is the option of painting the pipe. You'll need thick coverage and darker paint would be better. This will extend the life of the pipe.

 
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