Many homes built prior to 1973 have galvanized steel pipe used for their fresh water supply. Galvanized steel pipe has an expected life span of about 40 - 50 years and will eventually need to be replaced. One of the problems with galvanized steel pipe is it corrodes from inside causing a decreased in water flow. What happens is, the inside of the pipe gets smaller and smaller. Several months ago I found a piece of half inch galvanized pipe under a house I was inspecting. It was about twelve inches long. When I tried to look through the end, it was so corroded I could not see light though the pipe.
So what do you do if your house has galvanized pipe installed? You have probably heard commercials for re-piping your house. These commercials talk about when someone runs a faucet in another part of the house, you are in the shower, and the water flow slows down and goes cold. Copper pipe seems to be the choice that people seem to choose. Most home owners hire a plumber to do the work which in my opinion is a wise choice, but some try to it themselves.
Home inspectors see several situations where a copper pipe is connected to galvanized pipes. These conditions include moving the water heater to the garage or a cabinet outside the house, remodeling the bathroom or kitchen, and adding a second or third bathroom.
Home inspectors usually can tell when the home owner tried to do it themselves because they connect the new copper pipe to the old galvanized pipe without the benefit of a dielectric fitting. The dielectric fitting is used to stop electrolysis from eating holes through the pipes. Electrolysis is a chemical reaction between the two metals. Itís unknown how long it takes for electrolysis to eat holes through the pipes. That depends on the condition of the pipes and the environment.
Most of the time the do-it-yourself homeowner will replace the pipes going through the attic or crawl space under the house but will not replace the pipes inside the walls that leads to sinks, bathtubs or showers. To perform the job correctly, walls need to be opened up, new pipe installed, and close the walls back up. Because of the extra work and expense, this sometimes doesnít happen.
The picture shows where galvanized and copper pipes are connected together without the benefit of a dielectric fitting. In this particular house, the owner remodeled the bathroom. They installed new copper pipes when they had the walls opened, but connected it to the old galvanized pipes under the house. I assume it was their plan to replace the old galvanize pipe in the near future.