In plumbing systems you have two sides; the supply and the waste. As Phoenix home inspectors, we observe both, however lately we are seeing high failure rates in the older waste systems.
Since the early 1970’s Phoenix area homes are plumbed most often using ABS plastic waste lines. Prior to that, the waste lines were plumbed using cast iron, galvanized steel, clay, paper & tar pipe (Orangeburg) and sometimes copper. These older piping systems are now failing at a significant rate. Most of the failures are occurring at joints, trap arms (horizontal section shown in the photo above), horizontal runs in the yard and at flanges like at the base of toilets. Since long segments of the waste lines are contained below slabs, in walls or below lawns it can be difficult and expensive to replace.
During a Phoenix home inspection it is not possible for the inspector to see the majority of the waste lines. The inspector will operate multiple fixtures in order to attempt to overload the waste system. If a severe blockage exists on the day of the inspection, it should be possible to detect. For a detailed evaluation, you may want to consider hiring a plumber to perform a fiber optic video analysis of of the waste lines. The cost for such a test may vary and starts in the $300 range. With a video analysis, the technician can view the piping from the interior and determine the location of any defects.
It is our opinion that video analysis of the waste lines is highly suggested for the prudent homebuyer of a property built prior to the 1970’s. Even if nothing problematic is found, you will receive a lovely video of your waste line interior to share with family and friends.