UV Degradation of PVC: Solutions for Safe Use in Rainwater Systems

[uluru]

Hi everybody,

I'm involved with a project that wants to use PVC pipes as gutters for a rainwater harvesting system. The water is intended for human consumption (after it passes through clay filters to take care of biological contaminants). I've been looking at PVC degradation under UV and there doesn't seem to be a clear answer for what contaminants may be released from UV exposure, or what a (safe) method of protection might look like. I've been reading about latex water-based paints but don't really understand if they are safe to use with drinking water.

Any ideas?

 

[MrSid]

I have been looking at surface modification of PVC and other plastics to chemically alter their hydrophobicity and possibly allow coating with an inert and bio-passive coating- there is some literature that is pertinent to your question, as it covers free radical aqueous attack on the polymer, something that would be involved in photo degradation...

This Fenton chemistry (Fe+2 and H2O2 at low pH) works by radical hydroxyl abstraction of labile functionality on the polymer and there is literature that works out Fenton chemistry using photo activation. The biggest issue may be physical degradation and promotion of biofilms and anaerobic bacteria populating the degraded surfaces and cracks, rather than detrimental leached chemicals. For my interest, this is what I want to achieve with free living soil Nitrogen fixers. But the literature exists that may cover the chemistry you are up against.