Does UV light degrade plastic? If you purify water in a PVC plastic tube, what will happen to the plastic?

Question

My company, SunnIght Solar, wants to manufacture a solar powered water purifier - I have reviewed the UC and MIT web sites, however, the information on the problems with UV and PVC are not clear. [e-mail]

Answer 1

Yes, UV degrades plastic, and PVC is one of the worst of the clear plastics in this regard. Google "UV plastic degradation" and "plastic UV resistance"for a wealth of information. You also have to consider the UV transparency of the plastic, so the UV can get into the water and do some good. Looking at your website, I'd suggest trying to interest a good plastics engineer in your cause.

Answer 2

Yes, PVC degrades rather rapidly in UV, and would also be adding impurities to the water. But solar water purification by distillation has been around a long time, and can be done very cheaply. It just doesn't produce a large volume. There are UV-resistant plastic films like Monsanto 601 used for greenhouses. That may be a better direction to look. It survives UV for years, but I don't know if it transmits UV.

Running water through strata of sand removes most organic contaminants. Ground water that's a reasonable distance from humans and other animals and pollution sources is usually clean. Desalination or removal of other inorganic contaminants is another matter. Distillation and reverse osmosis are the most commonly applied tools there.