Buying an Old House – The Plumbing System

Lots of people love the idea of living in an older house. They love the “character” that only old houses can bring.  I get that.  But I’m seeing a trend of people wanting to go this route with no knowledge of what it really means to own an old house-or the cost of keeping one up and running.  Anyone who has lived in an old home for any real amount of time will tell you its a labor of love.  Old houses need constant upkeep (more so than their younger counterparts), and if you have ever tried to re-hab an old house, you know it can feel like a huge hole in your yard that you dump money into every day.  You know, “the money pit.”

My city, Louisville, KY has an area of town known simply as “Old Louisville,” which is packed full of old Victorian style solid brick houses.  It is the third largest such district in the United States.  Old Louisville also has the largest concentration of homes containing stained glass in the nation.  Pretty cool, eh?  Needless to say I get to inspect lots of big, old houses. That, too, can be a love-hate relationship.

Let’s dive into the plumbing system of an old house.  Old pipes can look fine on the surface, but looks can be deceiving. Over the past 100 years or so, several different types of material have been used for plumbing in homes.  Clay pipes, cast iron, and galvanized steel were the most commonly used forms back in the day.  All of these have been replaced with modern plastics in recent years, but millions of homes still have the old systems; and one day they will have to be replaced due to failure.

For clarity’s sake, the supply line is the pipe that brings water into the home and distributes it throughout. The waste lines are the pipes that take the sewer water away from the house.

Clay Pipes

Clay pipes (or vitrified clay pipes, if you want to be technical about it) are what most sewers were made from in the 1800’s to early 1900’s.  Clay pipes have been around for much longer than that though.  Some of the earliest pipes ever discovered date back to about 4000 BC in Babylonia.  The issue with having a buried clay pipe in your yard is that they are known for cracking or breaking over time because clay is brittle.

A clay waste (or sewer line) is comprised of many short sections of pipe that fit together.  They’re short because the pieces are heavy, but short sections mean lots of joints where bad things can happen.  Cue the tree roots.  When a breech in the wall of the pipe happens, roots, dirt, and everything in between begin to settle inside the pipe.  Over time this will lead to a clogged waste line in the middle of the yard.

At this point there are two options. You can either dig up the yard and replace the pipes, or hire a company that does “lining services.” That is, they claim to use the old pipe as a chase and pull a new liner through the old pipe.  I’ve never seen this done, but in theory it seems possible. 

Clogged Sewer Waste Pipe

Here you can see how tree roots can work their way into clay pipes.

Cast Iron

Cast iron pipes have been around a long time as well.  It’s not uncommon to see cast iron sewer pipes last 80-100 years, sometimes even longer.  However, cast iron pipes have a certain type of failure that is easy to spot…rust.  The thing to remember is that cast iron rusts from the inside out. That means that while it may look fine on the surface, your pipe could be paper thin in reality.  Long horizontal runs of cast iron pipes also crack quite frequently, a result of corrosive sewer gases.  When you are looking at an old house, and you see cast iron pipes, pay attention to the areas of rust around the collars of the connections. That is where I typically find them failing.  Also, if you are seeing pipes that look freshly painted, it could be someone trying to cover up a badly rusted sewer pipe.

Failed Cast Iron Pipe

Here is an old cast iron waste pipe that has had silicone smeared all over it to try and stop a leak.


Rusting Holes in Sewer Pipe

Here you can see pin hole leaks that seal themselves shut by rusting over.


Split Cast Iron Pipe

A horizontal run of a cast iron sewer pipe that has cracked from years of corrosive sewer gas exposure.


The thing to remember is that cast iron rusts from the inside out.  That means while it may look fine on the surface, it could be paper thin in reality.  If the cast iron is around 80-100 yrs old, it’s getting close to the end of its life.

Galvanized Steel Pipes

Galvanized Steel Pipes were used as both supply and sewer pipes up until around the 1950’s in Louisville.  When steel has been galvanized, it has had a zinc coating applied to the steel to help prevent rust.  Once the zinc coating wears off, the rusting begins.  Galvanized steel water pipes are bad news.  They rust and close up like an artery that has seen too many cheeseburgers. You can also get some pretty nasty tasting water from steel supply pipes. Louisville’s water is voted as some of the nation’s very best tasting tap water, and you wouldn’t want to spoil it with crud filled water pipes.  Obviously when this happens it cuts the flow down dramatically as well.  Like I said, bad news all around.

Rusted Galvanized Water Pipe

Here is an old galvanized steel pipe. Notice how it is rusting on the inside.  This will continue until it stops flowing water all together. But more importantly, do you want to drink water from this pipe?

Supply lines are not the only problematic pipe when it comes to galvanized pipe.  Lots of old houses have waste lines made of the same stuff.  They, too, suffer from the same fate of rust and buildup over time.  Most of the time I see this stuff being used as main sewer lines throughout the house, that tie into a cast iron main sewer stack to head out to the sewer at the street.

Old Abandoned Sewer Pipe

Here is an abandoned galvanized waste line in a crawlspace.  Notice how it’s an old piece of galvanized pipe connecting into a cast iron main stack. Those two typically go hand in hand.


Clogged Galvanized Sewer Pipe

A close up of a clogged galvanized sewer line. This home was about 75 yrs old. Most of the old plumbing had been upgraded to modern PVC pipe.


So, as you shop for your new (old) house, pay attention to what you see in terms of plumbing pipes.  A total plumbing replacement job on a big house is “new car money.”  If you notice little bits of PVC pipe sprinkled in here and there, that is a sign that the owners have had problems in the past, but didn’t want to bite the bullet and spend the big money to have it all replaced.  It’s inevitable. These old pipes will fail.  You just don’t want to be caught off guard when they do.