NJ Master Plumber
I say to use whatever materials you're comfortable with. Edpm has alot of resistance to various chemicals. Its pretty good stuff overall. Ive done some work doing industrial plastics where they run some nasty chemicals through it and engineers spec it. Theyvgo over their choices and critique everything. Propress has been good there.yes I knew that, but it still degrades with some chemicals..and some systems can become acidic..like if you dont change your antifreeze in your truck, it becomes highly corrosive and you end up blowing head gaskets and other issues....just look at how many plumbing items get invented and then taken off the market when they start to fail, im not saying propress will be one of them..for me it makes no sense to use...if I was doing big commercial work and large mains then I would have to figure out the cost difference and see which one is more profitable...in the end that is one of the final things that determine the use of a certain system or not..
I used an edpm liner for a koi pond, its tuff stuff and after 20 years it still held up, but NO chemicals were in the water...
Personally I'm comfortable running propress all day long. That being said it's still essential to know how to solder at my co. There are times where its still needed.