when do you decide to repipe?

Question

So I had one of my rental having many leaks issues that we needed to remove the flooring and repipe half of the house plumping (mind you - its concrete slab, such a pain.) while my tenant is occupying it. when I bought the property I didnt replaced the plumping because it seemed fine and house (70s built) didnt show really any leaks or issues. It was a fixer upper that I fixed only the electrical and added the HVAC. Had me thinking I wish I did replace it before moving in the tenant and putting in flooring.

On the other hand another rental that I did replace the entire plumping before moving in the tenant, I RARELY have issues because its brand new piping.

Had me wondering, when do you guys decide that you want to repipe the entire property before moving in a tenant? Assuming you cant see the entire piping and its slab? Is there a certain year that you decide that you HAVE to repipe it? Do you try to stick to buy houses built in certain years that the pipes should last?

JD Martin · Answer

That's tough when you're talking about a slab setup. Plumbing materials vary depending on different parts of the country, but *in general* (I worked as a plumber in college and of course have many years of old rental experience) your plumbing materials are going to look like this:

Drinking water: Before 1960: galvanized steel (most people didn't have running water in a house old enough to use pure lead). From 1960-1980's mix of galvanized steel and copper. From 1980's to early 2000's mix of polyethylene pipe, PVC, CPVC, copper, and once in a while galvanized. From early 2000's to present PEX, with lesser copper and CPVC and once in a while PVC.

Issues: Galvanized rusts from the inside and pops pin holes. Copper wears away especially if your water runs acidic and pops pin holes. Polyethylene pipe is total crap and splits. PVC & CPVC get brittle over time and can crack especially at glue joints and threads, CPVC more so than PVC. PEX pretty bulletproof, if it's going to leak it's usually at fixtures or crimp bands or where someone poked a hole with a drywall screw.

Waste water: Before 1960: Cast iron and occasionally clay (unusual inside a house but found in the ground) and once in a blue moon orangeburg. From 1960-1980's cast iron, steel and plastic in the house, cast iron & plastic outside. From 1980's to present ABS (black plastic) or PVC.

Issues: Cast iron develops tubercles inside and clogs, also gets brittle and can crack. Root intrusion at leaded joints. Clay major root intrusion as pieces are usually 3 feet or less in length, can crack. Orangeburg disintegrates in place. Steel rusts through. ABS plastic is more brittle than PVC and also thinner walled so it's easier to crack or deform. PVC is pretty bulletproof on wastewater but can get brittle and crack near joints or threads, rocks can poke holes in it in the ground.

If I had a house from the 60s or 70s with the plumbing in a slab I probably would have replaced it when I was rehabbing. That doesn't help you now. Next best thing to do is see if some/all of the plumbing rehab work can be rerouted outside the house (easier to do if your plumbing fixtures are on outer walls) or through an attic space dropping down into the necessary rooms.

Alecia Loveless · Answer

@Mario Am I’ve had two 1890s 7000sq ft homes in New Hampshire that still had a lot of older plumbing in it. We rarely ran into any problems with it and if there was anything wrong we only replaced things on an as needed basis. As these were Mansions built by wealthy families perhaps it matters somewhat the quality of the original materials as well as the quality of the water running through them as mine had spring fed water running through them.

Richard F. · Answer

Aloha,@JD Martin gave a pretty good rundown on the types of pipes, and generally what to look for. I would add that both the cast iron waste, and the galvanized supply lines are much more troublesome than later materials (so far), so if your unit was built pre-1985, you are at 38 years and certainly due to repipe everything. Why? ANY leaks/slow seepage has/will cause significant damage and attract carpenter ants or termites depending on locale. Repairing the damage if it goes unseen, or simply ignored for a couple years, will be an expensive fix in addition to the repipe. This is also why I always preach that annual walk through inspections focus on checking all potential areas for ANY possible small signs of leakage. Water is your #1 enemy as a LL.

It is common on kitchen and bathroom sink waste lines for the threads on the pipe nipple protruding from the wall that your sink drain connects to, would be corroded to the point where the threaded joints actually disintegrate, and water will seep down the inside of the wall. Also, the horizontal cast iron waste line to those sinks will corrode and acquire a buildup of scale on the inside, which will "catch" paper products and debris leading to more frequent clogs. This scaling also leads to splitting of the pipe due to the expansion of the corrosive material. These splits will be hairline cracks initially, with minor, but constant, seepage inside your wall...of waste water.

On the supply side, galvanized pipes also corrode from the inside out, and can also split simply from the corrosion. More often however, they will get a buildup of minerals at restrictions of the line, especially at elbows and T's, and predominately on the hot water lines. This causes notably reduced flow to the hot faucets, especially those closest to the water heater. (Often you can "solve" low flow of a hot water faucet by changing any/all elbows you can access from the water heater to that faucet.)

So, the short answer to your question is...when repair costs due to plumbing leaks and/or blockages start rising notably, or you are observing several signs of hidden leaks.Once you are past the 25 -30 year mark, you are bound to have more leaks, stoppages, and low flow (as well as prior, poor, repairs). This also applies, to a certain extent, to the various PVC/ABS lines which age, AND; in the past they used schedule 40 for supply lines, now usually schedule 80, which is a heavier gauge and therefore longer lasting. Many times these lines are buried in earth, where shifting, tree roots, and other natural events can more easily cause a leak as they age. Lastly, PEX is prone to be chewed on by rodents.

Waste lines can have their life extended with routine preventative maintenance. If there are trees anywhere nearby, pm becomes more critical, as those roots WILL make their way into your system.

when do you decide to repipe?

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