The problem with PEX Pipe

Cross-linked polyethylene or PEX pipe has been on the plumbing market for a several years and has been accepted by most plumbers as an acceptable substitute for copper piping in potable water systems.  There are at least two methods by which PEX pipe is manufactured and depending on the manufacturer, theirs is the best way.  However, regardless of the method of manufacture, PEX pipe has a couple of drawbacks.  PEX pipe is subject to degradation by exposure to chlorine, ultraviolate radiation, and rough handling.  I bring this up because I am presently working on a case involving extensive water damage due to a leaky PEX pipe.  It seems that the pipe cracked longitudinally and released a great deal of water into the crawl space causing damage to the subflooring and consequently, the interior flooring as well.  This scenario isn’t unusual. But, after the hot water line was repaired, a second crack developed in the same line, only days after the first crack was replaced.  To make matters worse, a short time later, a third crack occurred, again, in the same hot water line.  It almost seems that the fact that a hot waterline is involved has something to do with the failures and there are accounts on-line of people having similar problems.  However, according to the manufacturer, as long as the conditions of the water do not exceed 80 psi and 140 deg, the piping shouldn’t be affected.  In addition, as long as the chlorine level is below 3500 parts per million, again, the piping should not be affected.  I’m not sure how accurate that information is since it tends to conflict with the pressure and temperature information written on the exterior pipe wall.  As for the chlorine level,  I have found reports stating that chlorine will continually degrade PEX piping, the greater the concentration, the shorter the service life.  I have also found that the failures affecting PEX pipe currently are similar to the type of failures that were affecting polybutylene pipe, for which there was a massive recall.  As far as I can tell, there are currently no recalls for  PEX pipe.

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About rjhillconsulting
R.J. Hill Consulting is a forensic consulting engineering firm that specializes in performing failure investigations for attorneys and insurance companies. Mr. R.J. Hill is a registered professional (mechanical) engineer with over 37 years of experience, 33 years in private practice. Please visit www.rjhill.com to see the kinds of forensic investigations that Mr. Hill performs.

2 Responses to The problem with PEX Pipe

  1. Our water supply is treated with chloramine salts rather than chlorine. Significant leaks can occur where PEX piping is used with brass fittings with this kind of sanitation chemical. The chemical interaction produced between the PEX, brass and chloramine salts eats away at the brass with corrosion occurring, small leaks turn into big problems over a short period of time. Caution should be taken to find out how your water supply is made safe. Within 6 months from finishing our new home, you could easily see the corrosion inside the brass. This fix was an additional pre-treatment filtration system at $6K. All copper would have been far less expensive.

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  2. gold account says:

    PEX (or crosslinked polyethylene) is part of a water supply piping system that has several advantages over metal pipe (copper, iron, lead) or rigid plastic pipe (PVC, CPVC, ABS) systems. It is flexible, resistant to scale and chlorine, doesn’t corrode or develop pinholes, is faster to install than metal or rigid plastic, and has fewer connections and fittings.

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