Pressure that fails overnight is a valve, a break, or the utility. Pressure that has faded over ten years is almost always the pipe itself, and in Miami’s pre-war and immediately post-war housing that usually means galvanized steel.
What galvanized does, and why it takes decades
Galvanized pipe is steel with a zinc coating on the inside. The zinc is sacrificial: it corrodes so the steel does not. It works, and then it runs out.
Once it does, the steel underneath begins to rust, and rust occupies more space than the metal it came from. The pipe does not spring a leak — it narrows. A three-quarter-inch line ends up with the bore of a pencil, and every year the opening is slightly smaller than it was.
That is why nobody notices. There is no day on which the pressure went. There is a slow accumulation of small irritations that get blamed on the city, on the season, on the neighbors filling a pool.
Telling it apart from the cheap causes
Four things produce the same complaint and cost a fraction as much. Rule them out first — in this order, because it is the order of increasing effort.
One fixture only. An aerator or a cartridge. Unscrew the aerator at the faucet, rinse the screen, refit. In this water it is the single most common cause of “no pressure” in a kitchen.
Hot only. The heater, not the supply. Either the shut-off on the cold inlet is partly closed, or scale has built in the outlet.
Everything, but only sometimes. A pressure regulator failing, or genuine demand — a neighborhood where the mains struggle at seven in the morning is a utility matter, not a house matter.
Everything, always, and getting slowly worse. That is the supply pipe, and that is galvanized.
The confirming test takes ten minutes. Attach a gauge to an outside hose bib and read it with nothing running: on a healthy Miami system you should see a strong, steady figure. Then open two fixtures inside and watch. A pressure that holds steady while the flow indoors collapses is the signature of a restricted pipe — the force is there, the opening is not.
Where this lives in Miami-Dade
Galvanized supply is a dating exercise. It was standard until roughly the 1960s and disappeared from new work after that, so the map follows the age of the housing stock rather than any geography.
Coral Gables is the clearest case: pre-war homes where the original services frequently remain in the walls behind finishes nobody wants to disturb. Hialeah and North Miami have large tranches of older single-story housing where the supply and the waste are both original. Older parts of Coconut Grove and Miami Beach are the same, often with partial replacement done decades ago that stopped wherever the wall got difficult.
Anywhere built or fully renovated after the mid-1970s does not have it, which is most of Doral, Kendall and every oceanfront tower.
What replacement actually involves
A repipe is not a plumbing job so much as an access job. The pipework itself is straightforward; what takes the time is reaching it and making good afterwards.
The runs are replaced in copper or PEX, routed to avoid opening more wall than necessary — often overhead through an attic rather than chasing the original path, which is faster and leaves the new line somewhere reachable. Openings are cut where they have to be, and the honest part of any quote is who closes them and to what standard.
Two decisions worth making deliberately:
Partial or whole. Replacing the accessible half is cheaper today and means a second disruption later, usually to reach the part that was hard the first time. Where the original pipe is uniformly at end of life, a partial is deferral rather than a saving.
While the wall is open. Isolation valves at every fixture, a new shut-off, and a pressure regulator if the incoming figure warrants one all cost very little at this moment and a full day’s work at any other. This is the one opportunity.
What it costs you to leave it
The flow is the symptom people live with. The two consequences they do not expect are worse.
Rust from the supply reaches the water heater and settles, which shortens the life of the tank and shows up as discoloured hot water. And a pipe thin enough to restrict flow is thin enough to fail: galvanized that has reached this stage tends to start leaking at the threads, inside walls, which is a considerably more expensive way to find out.
If your house is the right age and the pressure has been fading for years, the pipe has already told you. See what a repipe involves, or send us the details and we will put the condition in writing before anybody quotes on it.
What to check before you call anybody
Ten minutes with no tools beyond a magnet will tell you most of what a first visit would.
- Find where the supply enters the house and look at the first three feet of pipe. Dull gray, threaded joints, magnetic — galvanized. Bright or dull orange, soldered joints — copper.
- Look under the kitchen sink and at the water heater. These get replaced first, so copper here and galvanized at the entry means a partial repipe that stopped somewhere.
- Run the cold faucet at the furthest fixture from the entry and compare it with the nearest one. A healthy system is broadly even. A galvanized one falls off sharply with distance, because every additional foot of corroded bore takes more away.
- Check the hot and cold separately at the same fixture. Both poor points at the supply. Hot alone points at the heater.
- Fill a bucket from an outside hose bib and time it. Thirty seconds gives you a number you can repeat in a year, which is worth far more than a memory of how it used to be.
Write down what you find. A plumber arriving to “low pressure” starts from nothing; a plumber arriving to “galvanized at the entry, copper under the sink, furthest bathroom much worse than the nearest” starts from the answer.