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Check for rust in galvanized pipes

QuestionWe have a 1911 house with many old galvanized pipes. When someone elsewhere in the house uses water, the person taking a shower is subjected either to a blast of freezing cold or scalding hot water.

I was wondering if a pressure-balance valve would work for us even if we don't replace our galvanized pipes, or would we have to replace the pipes, too?

AnswerIn most cases replacing the existing tub-shower valve with a pressure-balance valve should remedy the problem. Having said that, however, I would still check a few things before going through the expense of changing the valve.

First check that the main water line shut-off valve is fully open. Also check to see that the shower valve doesn't have any scale deposits and/or rust lodged in the unit. To do this, you'll have to turn off the water and take the valve apart. While you're there, check washers, O-rings, and the cartridge, depending on the manufacturer of the valve.

Since you have galvanized pipes and they are almost a century old, the pipe interiors are most likely rusted. One way to find out for sure is to turn the water off for about 30 minutes. Be sure to open all faucets once the water is off—the open faucets will help to drain the hot and cold water lines. Now close all the faucets and turn the water back on. As the water enters the pipes, it will dislodge rust and carry it on up to the faucets.

When you turn the water on at the faucets, you'll get some air and water spitting before the main flow starts. At this time (and in most cases) you will notice that the water may not flow smoothly from the faucet spout in a steady stream; it may even be shooting off to one side. This is a good indication that the aerator is plugged with debris. Remove the aerator to see if rust is lodged within the unit. While this inspection will tell you that rust is present in the lines, it will not tell you whether or not the pipes are starting to get restricted from that rust.

In our case, it wasn't until I removed most of the water supply lines while remodeling our bathroom that I discovered sections of the galvanized pipes that were more restricted than others.

The only way to determine rust restrictions in your pipes is to actually take a peek into the center of them. Yes, you can do this inspection yourself and it is certainly easier if your galvanized pipes are exposed. Think of yourself as a "doctor" going in for a little "exploratory." Alternatively, you could hire a plumbing contractor and take advantage of his experience working with galvanized pipes.

You can inspect both hot and cold water lines through unions found in the pipe centers. First, turn off the main shut-off and drain the water lines. Then loosen the union to separate the pipes. Have a bucket handy to catch the water, otherwise it will be all down the front of your clothes. Get a buddy to separate the pipes by pulling one to the left and the other to the right while you look directly into the center of one half of the union with a flashlight to see if there are any restrictions in the center of the pipe. Look into the other half of the union as well. I would also check other unions and inspect those pipes as well. This inspection will help you decide whether or not to replace the pipes.

I'm interested to learn in which direction you decided to go and whether or not you followed through with inspecting the water lines yourself. Please let me know how your project turned out.

Copyright © 2004, 2006, & 2008 LAF/C.R.S., Inc. All rights reserved.
Question answered by Leon A. Frechette.

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C.R.S., Inc. · Spokane, Washington · USA

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