Most of what is written about Miami plumbing is about old buildings, because old buildings are where the dramatic problems live. If your house was built in the nineties or later, none of it applies to you — and that is not the same as having nothing to worry about.
What you almost certainly have
Copper became expensive, and the industry moved. Two materials replaced it in Florida residential work, and between them they cover most of what has been built here in thirty years.
CPVC is the cream or tan rigid pipe, joined with solvent cement. It dominated the nineties and 2000s. It is cheap, it handles hot water, it does not corrode, and it is completely immune to the scale that quietly strangles galvanized.
PEX is the flexible tubing, usually color-coded red and blue, joined with crimped or clamped rings. It took over more recently. It bends around corners instead of needing elbows, it tolerates a degree of freezing, and it is faster to install, which is most of why it won.
Both are good materials. Neither corrodes. What they do instead is fail suddenly.
How CPVC actually fails
CPVC does not wear out evenly; it becomes brittle, and then something cracks. Three things drive it.
Age and heat together. The hot side ages faster than the cold side, and a run passing through a hot attic ages faster than one in a conditioned wall. In a Florida attic that is a meaningful difference over twenty years.
Chemical incompatibility, which causes more failures than most owners ever hear about. CPVC is attacked by a long list of ordinary building products — some spray foam insulation, some firestop sealants, some thread sealants, certain oils and adhesives. A pipe that was touched by the wrong product during construction can fail years later, and the crack will be exactly where the contact was.
Overtightened or stressed joints. Solvent-welded fittings are strong but unforgiving of being levered into place. A joint installed under stress carries that stress for its whole life.
The signature is a split along the length of the pipe or a crack at a fitting shoulder, releasing a great deal of water very quickly. There is no dripping phase to notice.
How PEX fails
Less often, and differently.
Fittings rather than pipe. Most PEX problems are at the connection — a crimp ring that was not fully seated, or in older systems brass fittings suffering dezincification in aggressive water.
Sunlight. PEX degrades under UV. Tubing stored outdoors before installation, or a run visible in a garage near a window, can be compromised long before anyone connects it.
Rodents. It is chewable in a way copper is not. In an attic this is a real failure mode, and an irritating one to find.
Where this is the local condition
This map is the inverse of the cast-iron one.
Doral is almost entirely post-1990 construction — newer homes and townhouses, mostly CPVC and PEX, with a completely different set of failure modes from anything east of it. Newer Kendall developments are the same. So is most of what has been built in Miami proper in the last twenty years, and every oceanfront tower in Sunny Isles Beach.
If you live in one of these and have read that Miami has a cast-iron problem, that is true and it is not about your house.
What to check, and when
Because these materials give no gradual warning, inspection replaces waiting.
- Look at the water heater connections. Hottest point in the system, and where CPVC brittleness shows first. Discoloration, chalkiness or a hairline at a fitting shoulder is worth acting on.
- Look in the attic, if runs pass through it. Heat, UV through a vent, and rodents all live there.
- Look where pipe passes through framing or foam. Contact with the wrong product is invisible until it is not, and a stain at a penetration is the tell.
- Check that every angle stop turns, twice a year. On a system that fails suddenly, a working shut-off is worth more than on one that fails slowly.
- Know where the main is. CPVC does not give you time to look it up.
The honest summary
A newer house has better plumbing than an older one. It also has plumbing that will not warn you, and the right response to that is not anxiety — it is knowing where your shut-off valve is and being willing to look at things occasionally.
If something has already let go, see what leak work involves. If a second one follows within a couple of years, that is the point at which a system rather than a fitting is talking to you, and repiping becomes the conversation.
What this means when you are buying
An inspection report on a newer property reads very differently from one on an older one, and the difference trips people up in both directions.
What will not appear. No cast iron, no galvanized, no slow decline to negotiate over. Buyers coming from older stock sometimes read a clean plumbing section as meaning the system is new. It means the system is a different material, and a 1996 house has thirty-year-old CPVC in it.
What is worth asking for anyway. Whether the attic runs are supported and clear of contact with insulation; whether the water heater connections have been changed at any point; whether there is a record of any previous leak, because a repaired split is the best possible predictor of the next one.
What an inspector cannot tell you. Chemical incompatibility is invisible from the outside, and brittleness does not show until it fails. Nobody can certify that plastic supply has ten years left in it — the honest position is that it has been fine so far, which is genuinely different from a corroded pipe telling you exactly where it stands.
For a seller, that cuts the other way and in your favor: there is usually nothing here to establish in advance, which is one fewer thing to negotiate than an older property carries.