Old Plumbing Horror Story

[Russell W.]

Frequently people will post on the forums asking opinions about buying old houses/buildings, what to look out for during inspections and what considerations to make when structuring an offer. This is a short story about one of the things to look out for...

My wife and I recently moved into a single family home built in 1908. One of the things I always make note of (whether for my investment properties or for my personal residence as is the case in this purchase) is the type of plumbing for both supply lines and waste/vent stacks. With the exception of one remodeled area, our home was plumbed entirely in galvanized steel pipes, very likely the original pipes from 113 years ago. It was an issue I was aware of and willing to accept.

Our kitchen sink had been draining slowly since moving in, so I removed the p-traps, stuck a shop-vac in the trap arm to clean out as much sludge as I could, and reinstalled new traps. This seemed to help a bit, until it started slowly draining again. One trick I typically use in this scenario is to fill the sink to the brim and then pull the drain stopper. The head pressure of the water will usually push through whatever blockage is in the trap arm between the sink and vertical stack. In this case, it did nothing. With a sink full of about 5 gallons of water I decided to do what any homeowner with galvanized pipes should not do: plunge the sink.

With only a couple plunges, the sink drained, and quickly. Voila! Problem solved! That is, until I heard the sound of a torrential downpour coming from the basement... The amount of pressure caused by the plunger ruptured the bottom of the paper-thin galvanized pipe and let all the water out between the walls and down into the basement. After tearing out backs of cabinets, and then breaking away plaster and lath, I found the culprit. The first picture is the bottom of the pipe between the sink and the vertical stack. It likely was not pitched enough to provide proper flow to the vertical stack. As a result water would pool on the bottom portion of the pipe, and over time corrode the steel. Apparently it had been hanging on just enough to actually hold water. The second picture is a cross section of the 2" vertical stack I cut out. It had become so corroded and consequently gummed up with sludge, that the diameter was no more than 3/4".

So, the point of this story is to provide some visual insight into why galvanized pipes are a risk exposure. While this might not be typical in every instance, the fact is that galvanized pipes corrode over time. The question is how long will it take. It doesn't mean you shouldn't buy a property with galvanized pipes, but understand that they may need to be replaced at some point and the cost implications involved.