Things to Know About Galvanized Piping

By
Home Inspector with Aldrich's Home Inspections, Inc.

Up until the 1950s, galvanized steel (sometimes referred to as "iron pipe") was the most common plumbing pipe being used. So when you're looking at a house that's more than 40 years old, you can be pretty certain that it will have at least some amount of galvanized steel piping. And the older the home is, the higher its probability of pipe problems. 

The average life span of galvanized steel piping is approximately 40 years but that estimate largely depends upon the acidity and mineral content of the water. The main failure method of galvanized piping is to rust from the inside out. 

The rusting that occurs on the inside of the pipe is a chemical reaction. As with most chemical reactions, rusting tends to move faster with higher temperatures. That's why the pipes carrying hot water are usually the first to fail. 

The early signs of failure usually show up as weaker pressure and flow on the hot side when compared to the cold. Failure usually occurs at the threaded connection, which makes sense because the pipes are thinner at the threads due to material being removed to create them. (See the diagram below).

Galvanized steel pipe

It is worth noting that while the reduction pressure and flow might an indicator of early galvanized piping failure, there are many other possible causes of the reduced flow. Here are a few that come to mind:

  • Loss of pressure resulting from elevation gains (three-story houses are worse than one-story homes).
  • Private water systems that can't build up enough pressure in the system.
  • Installed whole house water filtration or treatment equipment.
  • An older water heater that might have sludge in the tank that is adversely affecting the pressure on the hot water side of the system. 

In summary, when I inspect a greater-than-40-year-old house, I expect to find at least some galvanized steel piping. And if in a house with galvanized steel piping I also find a reduction in pressure flow, I always recommend further evaluation of the plumbing system by a licensed plumber.

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Rainmaker
563,524
Chris Smith
South Simcoe, Caledon, King, Orangeville Real Esta
Re/Max Chay Realty Inc., Brokerage

Thank You for this information.  I have subscribed to your blog and bookmarked this post.

December 12, 2009 03:21 PM
Rainer
22,886
peter gyoerkoes
Exit Realty NFI

Thanks, I have an older investment house and the hot water on one of baths is slow, much slower than cold side. Do you think it may be leaking or just rusted up?

December 12, 2009 03:44 PM
Rainmaker
68,576
Vince Santos
Southeast Michigan Home Inspector
StepByStep Home Services LC

Around here it's common to see a combination of copper and galvanized. Homeowners like to replace galvanized pipes in visible areas with copper to increase pressure.

December 12, 2009 05:07 PM
Rainer
36,261
Jason Aldrich
Sequim, WA Home Inspector
Aldrich's Home Inspections, Inc.

Chris and Don - I am glad you found the information useful!

December 12, 2009 05:33 PM
Rainer
36,261
Jason Aldrich
Sequim, WA Home Inspector
Aldrich's Home Inspections, Inc.

Pete - There could be a number of reasons for the "slow" hot water. My guess is that it has nothing to do with a leak, but since you mentioned it, if you have visual access to the pipes from either a crawlspace or unfinished basement, I suggest verifying whether or not the pipes are leaking. This should be relatively easy as the supply pipes are under pressure and if they were leaking there will probably be a good deal of water telling you so. If the pipes are not visible, another way to check for leaks is to turn all the water off in the house and then go look at your water meter. If the dial on the top of the water meter is turning, then there is a leak somewhere in the system.

That being said, if your water supply pipes are galvanized, then the culprit is most likely rust. However, there could be a number of other reasons causing the reduced flow (e.g. smaller sized supply piping to that bathroom, the supply line is kinked, or the hot water shutoff at the sink is not fully turned on). If the reduction in flow is to a point where it is a concern to you, then I recommend contacting a licensed plumber to have them evaluate the condition and recommend repair options.

December 12, 2009 05:55 PM
Rainer
36,261
Jason Aldrich
Sequim, WA Home Inspector
Aldrich's Home Inspections, Inc.

Vince - I see a lot of that type of repair in my area too. It's a lot easier to replace the horizontal sections than the vertical sections in the walls.

December 12, 2009 05:58 PM
Rainer
15,904
Ralph Brady
Brady Home Inspection

The other thing to watch for with galvanized pipe is debris clogging the aerator screens.  If I have to turn off the water for a repair, my aerators will just about all be clogged up.

We have some pretty mild water here.  I see 50+ year old pipe still going strong.

December 12, 2009 09:44 PM
Rainmaker
238,853
Gene Allen
Realtor Hampton Roads Real Estate
Resh Realty Group

We expect our houses to live forever and not think about replacing items like that.

December 12, 2009 09:55 PM
Rainer
67,262
David Helm
Bellingham, Wa. Licensed Home Insp
Helm Home Inspections

Today all houses with galvanized pipes are at the stage of needing replumbing.  You may not always see leaks, but these pipes seep constantly.  when I replumbed my house, my water bill was cut in half.

December 15, 2009 05:14 PM
Ambassador
1,068,326
Charles Buell
Seattle Home Inspector
Charles Buell Inspections Inc.

David brings up an interesting point---pipes that can leak without leaking----evaporating quicker than they show up as active leaks.

December 17, 2009 08:45 AM
Rainer
36,261
Jason Aldrich
Sequim, WA Home Inspector
Aldrich's Home Inspections, Inc.

Ralph - Good tip about the aerator screens. Sometimes reduced flow at a fixture is caused by debris blocking the aerator screens. 

Gene - Your point is so true and sometimes one of the hardest things for both sellers and buyers to understand.

David and Charles - You bring up an interesting and important point that I neglected to include in my original post. Thanks for the additional insight!

December 17, 2009 11:07 AM
Rainmaker
1,177,673
Steven L. Smith
Bellingham WA Home Inspector
King of the House Home Inspection, Inc

I am finding fewer and fewer galvanized supply pipes anymore but I still see lots of galvanized drain pipes many of which are leaking.

December 19, 2009 03:32 PM
Anonymous
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Rainer
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Jason Aldrich

Sequim, WA Home Inspector
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