Old Water Pipe Problems

By The Old House Web

Bill the Inspector,

We own a fairly large home with 4-1/2 bathrooms. The 3rd floor bathroom is only occasionally used by guests. The flow of water seems poor as compared to the rest. Also, when first running water it is brownish. Water into the tub is just nasty sludge for a few seconds. When we purchased the home, we were told plumbing, heating and electrical have been updated. Our inspector listed the pipes as copper and pvc, but behind the 3rd floor tub and one of the 2nd floor tubs, the pipes are silver-gray, not reddish brown like the pipes in the basement. Are there any simple fixes for this?

Many, many homes built before the mid 1940s and some as late as 1960 have galvanized steel/iron water supply pipes. Once in a while, I'll find some brass pipes still in use. On some rare occasions, I'll find lead supply pipes. It's more common for lead to be used for drain pipes and underground water services, between the water main and the house. Identifying lead pipe is quite easy. The metal is dark gray and soft. When scratched (actually, easily gouged) with a screwdriver, a lighter color gray is revealed. Where the lead pipe connects to other pipes, there's often a big bulbs of lead at the joints. If you suspect lead supply pipes, have your water tested to be sure it contains less than the 15 ppb EPA action limit.

Galvanized steel pipes are the most common water supply piping systems originally installed in old homes. These are joined with threaded fittings and occasional large union joints. Galvanizing involves applying molten zinc. This creates a corrosion resistant coating on the interior and exterior of the pipes. Generally, this has been found to limit rust for about 45-65 years, although there have been inferior pipes that have failed earlier. Once the protection is gone, the corrosion begins. As steel corrodes, the rust expands, resulting in the interior dimension of the pipes being reduced. This restricts flow to the point that the pipe no longer delivers adequate flow to the fixtures being supplied.

There can also be corrosion on the exterior of the pipes. This typically occurs on pipes in wet or damp locations or in the ground. Many water pipes connecting the house to the main are/were galvanized steel. I still see many galvanized pipes supplying water to homes from wells. External corrosion is often at joints near fittings, where threads are "cut" into the pipe. Rust can also occur where galvanized pipes are directly connected to copper. This corrosion forms where the two dissimilar metals meet, unless specific fittings were used.

Brass water supply pipes are occasionally found to be still in use in some old buildings. They look similar to copper when tarnished from age. They are thicker walled than copper and not bendable. They also are usually joined with threaded fittings, like galvanized pipes. The life expectancy of brass water piping seems to be similar to copper. It can depend on the corrosivity of the water and the quality/thickness of the pipe. They can become clogged over time if there is excess lime in the water.

Typical repairs of old water supply piping systems usually consists of replacing only individual sections as needed. This is understandable, considering the major expense of repiping an entire house all at once. I've seen advertisements for products that remove lime buildup and rust and coatings that claim to protect the interior of the pipes. If these are even proven to be effective, it will likely only be a temporary repair. I have doubts that the cost and effort would justify only what I suspect would be a small extension of the service life.

If you find old sections of piping in your home, mixed with new sections, there's a reason some of the pipes have been replaced.

 




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