A galvanized nipple is often used in water supply piping as the last, short section of pipe that penetrates the wall for attachment of a shut-off valve for a plumbing fixture. It has male threads at both ends. The photo above shows a galvanized nipple for water supply under a bathroom sink that has been recently replaced, but the wall has not been repaired, and you can see the copper piping it is connected to inside the wall.

    One of the problems with galvanized nipples as they age is that the galvanized steel tends to develop a festering kind of rust called “galvanic corrosion,” which is an electrolytic reaction when you combine steel with copper and water.  See our blog post What problems are caused by connecting copper pipe/tubing directly to galvanized steel pipe? to learn more about it.

    This can result in early failure of the nipple, and a common place where we find it is at hose faucets like the one shown below. The corrosion has started a steady, slow leak in the wall, with a rusty drip stain as evidence.

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Here’s links to a collection of our other blog posts about PLUMBING PIPES:

• How can I protect my pipes to keep them from bursting during a hard winter freeze in North Florida?

• Can galvanized steel pipe still be used for new water lines in a house? 

• How can I tell if I have cast iron pipes in my house? 

• Why can't a sanitary tee be used for a horizontal-to-horizontal drain pipe connection? 

• What is the difference between green and white sewer drain pipes?

• Is a washing machine drain hose required to be secured at the standpipe?

• What are the abandoned pipes sticking out of the wall in my house?  

• What are the code requirements for plumbing vent terminations?

• What are the code requirements for layout of drain piping under sinks?

• What causes a gurgling sound when a bathtub or sink drains? 

• What is a "combination waste and vent" in a plumbing system? 

• What is a building trap?  

• What is a galvanized nipple?

• What are the pipes sticking out near my water valves?

• How do you accurately find a broken water pipe leak under the floor slab?

• What is the difference between water pipe and sewage (waste) pipe? 

• Are plastic pipes (PVC, CPVC, and PEX) safe for drinking water? 

• What is the difference between PVC and ABS plumbing pipe?

• What is the difference between water service pipe and water supply pipe? 

• What are the pipes on my roof? 

• How can I find out what type of water pipe runs underground from the water meter to the house (service pipe)?

• What is a P-trap?

• Why is old galvanized steel water pipe a problem for homebuyers?

• What does polybutylene pipe look like? Why is it a problem? 

• Which water pipes are an insurance problem and possibly uninsurable?

• Can you connect CPVC pipe directly to a gas water heater?  

     Visit our PLUMBING page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.