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WHAT IS THIS?

For no apparent reason you

• Notice a small spot of discoloration on a wall or ceiling
• See a mold mark that reappears even after initially being wiped away with bleach
• Feel a warm spot on a floor in a slab home
• Hear almost imperceptible water movement in pipes while knowing for certain that there are no leaky faucets or toilet fill valves

The above plus other indicators are telltale signs that invisibly behind walls and ceilings water is leaking from pipes and damaging the home.  Left without repair, damages can become extensive with often unseen, unhealthy mold taking over significant portions of a home.

HOW DOES THIS HAPPEN?

To answer this question, it’s important to look at the material used in your pipe system.

Perhaps the most common in the past 50 years is copper pipe with copper fittings assembled together on-site with no-lead solder.  Shortly after it is used, a protective oxide layer (patina) develops on the inside and out.  Additionally, copper has biocidal properties that prevent the formation of biofilms and it is extremely strong withstanding pressures north of 300 PSI or about 4X normal home pressures.  Over time, leaks can occur at pipe/fitting junctions because of excess flux (acid) used to clean the parts during sweating (soldering) and incomplete cleaning.  Unusually high flows or 24/7 recirculation flows cause wear (erosion) at junctions thinning material to below its pressure holding ability.  Pipe quality too can be an issue, because minute iron particles can be left on the pipe surface inside and out during manufacturing.  These particles establish galvanic reactions with the copper, chemically creating the all-too-common pinhole leak.  This reaction is speeded up by high TDS (conductive) water and heat.  It also appears more quickly in less expensive and often foreign sourced, thinner type M vs. type L copper pipe.  M type copper is identified by red markings on the outside and L type blue.  Pin hole issues with type M copper tend to appear after 15 years or so in hot water lines and with water supplies that have a TDS of 300 PPM and higher according to experienced plumbers.  We have concentrated our comments on situations involving multiple leak points.  Single point leaks can be attributed to rubbing against the structure, a pipe hanger, stone etc.

The second most common pipe and fitting material is plastic represented by white PVC, dark gray PVC, light gray CPVC and yellow (copper pipe size) CPVC all of which have an excellent reputation for leak-free longevity.  PVC is for cold water only and CPVC is rated up to 140⁰F so it is applicable for both hot and cold.  All are rigid materials and pipe-to-fitting connection is done with solvent cements.  Joints are normally cleaned with a solvent prior to the application of a cement resulting in a water tight bond ready for use after a few hours of cure time.  Unless penetrated by a drywall screw during construction or similar errors, random leaks after years of service are not expected.

Coming on strong in the last few years is PEX.  This is a Polyethylene material that is post-extrusion chemically cross linked either as a semi-rigid straight milky white (hot and cold), blue (cold only), red (hot) colored tube or as a tube typically coiled in 10-500 ft. coils.  Proper installation is critical to long term leak free service.  Leaks that do manifest themselves are normally at fittings where a cast brass fitting corrodes or a crimped collar over the tube wasn’t tight.  Another leak point in that area would be from a nick in the tube that grew over time.  If coiled-form material was used, forced straightening can cause stresses that result in radial cracks that begin to open and leak especially if the PEX has been weakened by chlorine in the water.  A combination of chlorine and pressures at or above 80 PSI is known to create axial cracks that leak. 

HOW IS IT REPAIRED?

There are very few options.  You can begin by having a single leak repaired which normally involves cutting out a section of a wall or ceiling to access a section of pipe containing the leak.  This pipe is then cut out a few inches on both side of the leak and replaced with the same size and material pipe.  Upon completion and pressure testing, the cut-out wall or ceiling section is replaced, the seam closed with patching plaster, then sanded and painted.  This entire process is messy, disruptive and expensive.   If you are fortunate, this is a one-time occurrence. If, however, there are repeat leaks, you can address them one at a time or resign yourself to having a chronic material or workmanship issue that requires replumbing of the home.  At this point, seek a company that specializes in replumbing homes that has an experienced crew.  Chances are, they will do the work with PEX to minimize the amount of wall and ceiling cutting and reduce the project time.  If you are on a chlorinated municipal water supply, be certain to install a Dime Water Aquafer or carbon filter to prevent damage to the tubing material.  If in a high-water pressure area such as southern California install a pressure regulator valve to be sure home water pressure is maintained below 80 PSI.