Cast Iron Drain Pipes

Although I am not a licensed plumber, cast iron drain pipes indicate an older system that needs to be monitored regularly to help detect problems. Simply looking at the exterior of the pipes might not indicate that there are problems with the drainage system since cast iron typically deteriorates from the inside out. Although I am not a licensed geotechnical engineer, some types of soil are corrosive to cast iron. Both interior and exterior deterioration of the cast iron pipes can lead to pitting and pinhole leaks (see Figure 1), followed by catastrophic leaks and failure. Tree roots are notorious for finding pinhole leaks in cast iron drain pipes and either crushing the drain pipes as they wrap around it, or entering the drain pipes through the pinholes, eventually clogging the drain and bursting the pipe.

If the cast iron drain pipes are under the foundation slab, failure can result in settling and cracking of the foundation. If the cracking and settling occurs towards the center of the slab foundation, the process of leveling and stabilizing the slab becomes more difficult and expensive. Some cast iron drain pipes are able to have the interior cleaned and sealed, thus prolonging the life of the system, and the process many times is less expensive than replacing the cast iron drain pipes. Consult a qualified plumber if drainage ever appears slow at sinks, toilets, bathtubs, showers, or laundry.

Unfortunately, I am aware that many Realtors advise home owners to run some Liquid Plummer or Draino down all the sinks, bathtubs, showers, and toilets prior to a property inspection. Such a tactic usually works quite well in preventing me from finding drainage defects during the course of my inspection. In many cases, using commercial drain cleaners is a band-aid rather than a cure, so if there  were problems which might have been detected during the course of a property inspection, those problems typically will reoccur shortly after the inspection. Again, consult with your Realtor about how you can protect your financial investment if functional drainage is not satisfactory after you close escrow, especially if there are cast iron drain pipes present on the property.

If you have any questions about anything, simply contact me.

Figure 1. Pinhole leak in a cast iron drain pipe.

 

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