Potable Water Piping: Plastic (Polypropylene) or Copper?

Hi Martine, I don¹t have any studies handy, but polypropylene is a good choice if you can keep the cost down. Unlike polycarbonate, polypropylene is not made with bpa. PP pipe has some interesting advantages, too. It is one of the ³cleaner² plastics, as plastics go, and it is heat welded so the joints essentially melt together becoming stronger than the pipes alone. Lots of variations too depending on whether you need it for if for potable, graywater, hydronic, chemical resistance etc. There are a couple other PP brands, such as the one made by ISCO. There is also a PEX replacement, Hyperpure aka PERT, if you don¹t need that commercial PP scale pipe. PERT doesn¹t have the crosslinking chemicals of PEX, so it won¹t have the chemical taste/leaching issue, and it can be recycled, unlike PEX. Brent From:

Hello Martine! I’m happy to report that your association of BPA and PP (polypropylene) is most likely a side effect of MAF. Monomer acronym fatigue (MAF) is closely correlated with trying to stay safe while being human in a modern world bathed with PVC, PET, PE, HDPE, and PVDF plastics. In all seriousness, BPA is a monomer used in polycarbonate chemistry, which is quite distinct from polyproplyene. I don’t think there is any association in practice. Aquatherm has long been touted as “green” and has been lauded by BuildingGreen and others over the years. I’ve never heard a reason to doubt it. Also highly durable. Polypropylene, especially as advertised in this context, is considered a relatively “clean” plastic. In terms of a health comparison, I can’t recall any known issues with copper piping, assuming lead-free solder. However, copper is very energy-intensive in production — off the charts in terms of LCA comparison with PEX — and therefore globally speaking could be implicated with health issues. Tristan ____________ Tristan Roberts The Laurentia Project @Tristan_Roberts tristan@thelaurentiaproject.com www.linkedin.com/in/tristandroberts 802-275-2881

Martine – I looked at polypropylene a few years ago when I was re-piping my house. I agree with Tristan’s comments about it, that is what I read as well. Ultimately, I opted for copper, being more time tested for human health, and for the reason that it was exposed in my basement (my wife loves copper). They were both about the same cost installed if I remember correctly (but copper was cheaper when I ultimately did the project ourselves and with a friend experienced in soldering). I also agree that the environmental impacts are considerable with copper, and the health effects are not negiglible either. From my notes: Copper is known to corrode under circumstances that sometimes occur in water supplies—in relatively acidic water, with a pH of 6.5 or less, and also in water with certain mineral concentrations. Newer homes with copper pipes may be more likely to have a problem. Over time (I’ve heard about a year), a coating forms on the inside of the pipes and can insulate the water from the copper in the pipes. In newer homes, this coating has not yet had a chance to develop. Excess copper in the water may not be an issue for most people, as our body can regulate the amount of copper we ingest. However, children under one year old have not yet developed this mechanism and, as a result, are more vulnerable to the toxic effects of copper. People with Wilson's disease also have a problem with maintaining the proper balance and should also exercise particular care in limiting exposure to copper. -C Chris Flint Chatto Associate AIA, LEED AP BD+C Principal ZGF ARCHITECTS LLP T 503.863.2324 E chris.chatto@zgf.com 1223 SW Washington Street, Suite 200 Portland, OR 97205 From: T

I recommend careful research before using polypropylene piping. There have been significant failures in large-scale buildings. Start by just searching online.

Interesting. Polybutylene pipe was known for its failures (there is yet another class action suit against them), and polyethylene has had some issues as well, but I haven¹t read about polypropylene failing. FWIW, polypropylene pipe manufacturer ISCO insures against damages from pipe failure and Aquatherm has a 20-year warranty. But, if anyone has experience with polypropylene failing, let me know. Stranger things have happened.

Just remember - unless you're filtering water where it comes in the building - it's being distributed (in most urban geographies) by cast iron, lead, and PVC piping before it gets into the building so doesn't really matter what you plumb the building with if you're not extracting the source contaminents.