Case of the Month: The toilet supply line failure

Nov 1, 2012 by

Our case of the month deals with a water hose failure.  A medical facility/outpatient surgery center suffered a toilet supply line failure, which caused extensive water damage.  The facility had been remodeled about a year earlier.  The water damage was bad enough by itself, but the facility was closed for renovation for several weeks.  Surgeries were postponed, treatments were delayed, doctors and nurses were transferred to other facilities, and patients were shuffled to other treatment centers.  The financial loss was significant.

Our client gave us the following observations when he assigned us the case:

  • The water supply line to the toilet was polymer braided and had separated at the crimped end.
  • Two different building water sources or systems were attached to the facility.  One had 50 psi of water pressure, the other had 136 psi of water pressure.
  • There was another toilet installed, using identical materials, which provided an example of what had been done on the toilet line that failed.  The other toilet hose had sharp kinks in it.

Our expert made his inspection and came to the following conclusions.

  •  The 136 psi water pressure was a red herring.  That system served another part of the building.  The water pressure measured at the toilet in question was 50 psi, so the excess water pressure in the other part of the building had no bearing on the hose failure.  The 50 psi was well within the normal range of water pressure.
  • The polymer braid was pulled out of the end cap that was crimped onto the inner hose.  There were no strands or fibers left behind.  Therefore, the braid did not fail. The crimp on the end cap failed.  When the braid was pulled out of the end cap, a section of the inner hose was left unsupported.  It then burst like a balloon.

The kinks in the line were the result of using too short a hose.  Apparently, the recent renovation had replaced the toilet supply lines (perhaps for cosmetic reasons). The replacements should have been longer by four to six inches to allow gentle, gradual curves in the form of an “S”.  Instead the short lines pinched and pulled each end (more like a “Z”).  A year of “pressure, release, pressure, release” cycles on the hose ends then pulled the braid out of the end.  The plumber saved a trip back to the warehouse to get longer hoses, but it ultimately cost hundreds of thousands of dollars.

You may ask, “Shouldn’t the end have stayed on regardless?  Isn’t this a manufacturing defect?” There is some merit to this line of thought, but any product will eventually fail if improperly installed.  This hose was stressed (pulled and pinched) in a manner in conflict with its design. It was too short to provide the gentle curve that the designers planned upon and it failed because of the improper installation.

A Side Discussion – Airplanes to Toilets?

Back in the 1960s, sports car racers began look to their friends in the aviation industry for better quality fasteners and hoses.  One improvement they found in the aviation mechanic’s toolbox was to surround a rubber hose with a stainless steel braid.  This gave significantly increased strength with minimal weight penalty.  The “look” of the racers on the track made its way to the street for high performance cars and the stainless steel “look” became associated with high performance in any field.  Eventually even toilet manufacturers picked up on it as well.

A stainless steel hose looks better than a black rubber hose, anyway. It appears to be much more “high tech”.

Other manufacturers copied the design and began to substitute plastic polymer braids for both toilet supply lines and faucet supply lines under the counter in the kitchen and the bath. At arms length, they look like metal, but their cost to manufacture is much less,. When you handle these, you almost feel cheated.  The strange thing about it though, is that the polymer hoses are generally a better materials choice than the stainless steel.  Stainless steel hoses are subject to corrosion by the caustic chemicals frequently used to clean (i,e, chlorine products).  Corrosion on stainless steel looks like a black spot on the metal braid, which most people think looks like mold.  What do you do to a mold spot in your bathroom?  You wipe it with chlorine bleach.  The tiny braided strands then corrode more and begin to break, giving a frayed appearance.

 

We have handled many cases where the frayed braid eventually failed to contain the soft rubber hose inside and the waterline then bursts.

 

Polymer braids are unaffected by these toilet-cleaning chemicals, and are therefore a much better product.  Making it personal, do you see “mold” spots on your stainless steel water supply lines?  Will you clean those black spots with bleach?