When does plumbing need to be rerouted?

Most reroutes come down to five situations. Knowing which one you're in tells you what to ask for.

### 1. You're changing the layout

Moving a kitchen island sink, shifting a toilet, enlarging a bathroom or adding a laundry room all move where water has to go. Supply lines are flexible about this. Drains are not, because they rely on gravity and have to keep a workable slope back to the main line, which is why drain pipe slope rules decide how far a fixture can move. A fixture that slides a few feet may be easy. One that moves across the house may need a whole new drain path, and sometimes a new vent too. Our page on permits for a bathroom remodel in Phoenix covers the paperwork side.

### 2. A wall, addition or structural change is in the way

Taking out a wall, adding a room, or opening a ceiling can expose pipes that sit right where the framing change is going. Before anyone cuts, the plumber needs to know what runs through that wall. If you aren't sure, start with how to find where your water pipes run. A pipe in the path of a beam, a doorway or a new footing gets moved around the change, not through it. This is the one reroute you can plan ahead of time, so use that: have the plumber walk the wall before the demolition date, not after.

### 3. The pipe material is failing

A reroute or repipe comes up when the pipe itself is the problem. Galvanized steel corrodes from the inside and can restrict flow and leak, and we cover the details in galvanized pipe problems. An EPA report on the subject looked at the rapid pitting failure of galvanized steel pipe used in consumer plumbing systems. Copper can fail differently. In an EPA research summary, localized copper corrosion, or pitting, is called a significant problem at many water utilities across the United States, and homeowners may not even notice the problem due to hidden plumbing.

That hidden part matters. One pinhole is a repair. A second and third in a few years usually means the pipe is telling you something. Look at signs of old, failing pipes and pinhole leaks in copper pipes, then read when to repair or repipe copper that keeps leaking.

### 4. A leak is buried in the slab

Slab leaks are the classic reroute in Arizona, since so many homes have pipe in or under the concrete. Instead of breaking the floor over the leak, the plumber shuts off the damaged line, leaves it in place, and runs a new one through the walls or attic to the same fixtures. Today's Homeowner says that when the leaking pipe is old or in poor condition, repairing only one section can lead to future leaks elsewhere, and that rerouting the pipe aboveground or through walls and ceilings can be a good alternative. It adds that this method avoids breaking the slab and can provide easier access for future maintenance.

Our full breakdown of the options is in how a slab leak repair works: reroute versus breaking the slab. If you're still working out whether you have one, how plumbers find hidden leaks explains the detection step.

### 5. A code or venting problem shows up

Sometimes the trigger is a drain that doesn't slope enough, a trap without a proper vent, or an old alteration that was never done to code. These usually surface during a remodel, a permit inspection or a home sale. If the fix means changing where a pipe goes, that's a reroute. If a vent has to change, see what a plumbing vent does and vent termination rules. We don't guess at code fixes from a photo. The plumber should point to the actual problem before quoting the change.

Here's the simple test. A repair fixes the pipe where it is. A reroute changes where the pipe is. Phoenix's building code draws the same line for permits. Its exempt-work list covers repairing leaks in pipes, valves or fixtures, provided such repairs do not involve or require the replacement or rearrangement of valves, pipes or fixtures.

Run through these questions:

• How many failures, and where? One leak in an otherwise healthy line points to repair. Several leaks, or leaks in different places, point to a reroute or repipe.
• Can the pipe be reached? Exposed or easy-to-open runs are cheap to repair. Pipe under a slab or inside a finished wall is where a reroute earns its keep.
• Is the layout changing? If yes, you're not repairing anything. You're building a new path.
• Is the material the culprit? If the pipe type is known to fail, a repair buys time, not a fix.
• Who owns the pipe? In Phoenix, the city handles issues from the street to the water meter, and, in the city's words, issues after the water meter are the responsibility of the homeowner. A reroute is a job on your side of the meter.

Sometimes the honest answer is that a reroute isn't needed. If a leak is at a fixture, a valve or an exposed joint, fix it there. DIY is reasonable for swapping a supply line or a faucet in the same spot. Anything that involves cutting into pipe inside walls, moving a drain or touching the main should go to a licensed plumber.

The details vary by house, but a well-run reroute follows the same order.

1. 1Confirm the problem and map the route. The plumber locates the failing or obstructed line and plans a path for the new one through attic, wall or crawl space.
2. 2Get the permit. More on this below. It comes before the work, not after.
3. 3Shut off and drain the affected section. Water comes off at the main or a local valve.
4. 4Run the new line. New supply pipe is routed to the same fixtures. New drain pipe has to hold its slope and connect to the vent system.
5. 5Cut over. The new line is connected, and the old line is capped or abandoned, so nothing feeds a dead pipe.
6. 6Test. The new section is pressure tested for leaks before it's covered. Ask the plumber to show you the result.
7. 7Inspect. The city inspector looks at the work while it's still open.
8. 8Patch and finish. Drywall, paint and any floor or ceiling repairs come last. Ask up front who handles them.

Timing depends on how much of the house is involved, and a whole-house job runs longer than a single-line one. Our page on how long a whole-house repipe takes sets expectations for the bigger version.

In Phoenix, almost certainly yes. The city's building code says that any owner who intends to alter, repair, replace or remove a plumbing system regulated by the code shall first apply to the building official and obtain the required permit. Its exemption for leak repairs comes with a catch: if a concealed pipe becomes defective and it becomes necessary to remove and replace the same with new material, such work shall be considered as new work and a permit shall be obtained and inspection made as provided in this code.

That is exactly what a reroute is. You're replacing pipe with new pipe on a new path.

Two practical points:

• The work has to stay open for the inspector. The code says work needing a permit shall remain visible and able to be accessed for inspection purposes until approved. Don't let anyone close the walls first.
• The current code applies. On June 18, 2025, the Phoenix City Council approved the adoption of the 2024 Phoenix Building Construction Code, per the city's building codes page. The administrative chapter says the plumbing code applies to the installation, alteration, repair and replacement of plumbing systems.

Other cities have their own rules, so if you live outside Phoenix, ask your city's building department. For a wider look at what needs one in Phoenix, see what plumbing work needs a permit. Gas lines are their own category: they need a licensed pro and a permit, full stop.

1. 1What exactly is wrong, and can you show me? A photo, a camera image or a test result should back it up.
2. 2Is a spot repair enough, and why not?
3. 3Where will the new line run, and which walls, ceilings or floors get opened?
4. 4What material will the new pipe be, and why that one?
5. 5What happens to the old pipe: capped, abandoned or removed?
6. 6Who pulls the permit, and when is the inspection?
7. 7Who patches and paints, and is that included?
8. 8Will the new run be pressure tested, and can I see it?
9. 9Will the price be written and firm before work starts, with no add-ons after?

Ask more than one company if the job is big. A plumber who welcomes those questions is a good sign.

A reroute makes sense when the pipe's path is blocked, failing or buried, and a patch would only delay the next leak. If it's a single leak in a healthy, reachable line, repair it and move on. HQ Plumbing & Air is licensed and insured, gives upfront pricing and free estimates, and offers 24/7 service if a line lets go before you've decided.