When a realtor tells us that “the plumbing has been replaced” in a house we are about to inspect, we try to determine what percentage of the plumbing was actually replaced. It is almost never 100%. Plumbing replacement in a house between 40 and 60 years old means that only new water supply pipes (the pressurized ones) have been installed. Drain piping systems (DWV) last longer under normal conditions, so they are not replaced until the house is 60 to 80 years old or more and, even then, often not completely.

   Also, sometimes there are a few short sections of old supply pipe behind the walls that require so much wallboard removal, and then wall repair afterwards, that the plumber leaves them if they appear to be in acceptable condition. The homeowner gets a better price for the job, but the pieces of old pipe continue to age in the wall or in the crawl space, and can cause new problems in the future.

The photo below shows the crawl space in a 1950s house where only part of both the supply and drain pipe systems have been replaced. Portions of the original galvanized steel have been replaced with CPVC (cream-colored plastic, covered in the black insulation in photo), and some segments of the cast iron drain pipe have been replaced with PVC (white plastic).

The new plumbing appeared to be about 10 years old, and the original material that remained was having new corrosion and leakage problems, as shown in the two photos below.

Other things to look for in a house that has been re-plumbed are:

1.  Insulation covering water supply pipes in the attic, crawl space, and exterior. Water expands when it freezes and fracture exposed pipes when that happens, so insulation is necessary in any area that may experience sustained sub-freezing weather in the winter.
2. Sufficient straps and clamps to secure the pipes in place, using materials approved by recognized rating agency and installed to building code specifications.
3. Locations that do not leave pipes exposed to damage from foot traffic nearby or stored items pushed up against them.

    If you are planning to have your house re-plumbed, be sure to clarify with the plumbing contractor what sections of pipe, if any, will be surface mounted under sinks or along walls and ceilings. Although surface mounted pipe is acceptable, it is not pretty. The trade-off is that installing new pipe inside the wall is sometimes much more expensive when it can’t be fished through the wall cavity. The work requires cutting out sections of wallboard, followed by a seamless repair and repainting. So surface mounting will save you money, and is usually the least offensive inside kitchen and bathroom cabinets, or in utility and laundry rooms.

    Also, will the plumber remove the old pipes or leave them in place? Rusty pipes with cut-off ends sticking out of the walls—like in the photo at the top of the page, with the new pipe surface mounted next to it—are also not aesthetically desirable. If you choose to live with the remnants of the old pipes still in place, we recommend that you have the plumber at least cap the ends of the pipe.

    Also see our blog post Can you live in a house while the plumbing is being replaced?

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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? 

• Is a hot water faucet handle required to be on the left? 

• What is a dielectric union? 

• What's that powdery crust on the pipe connections at the water heater? 

• If all the plumbing drains have water in them and you can still smell sewer gas, what's causing the problem?  

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