Cast iron was the standard drain, waste, and vent material for decades, and it can last a long time — but not forever. In older West Palm Beach homes the under-slab cast iron is now well past its typical service life, and internal corrosion is the issue homeowners run into again and again.
Why cast iron is a West Palm Beach problem
Much of West Palm Beach’s housing stock predates 1972, especially in established and historic neighborhoods like Old Northwood, Flamingo Park, and El Cid. Homes from that era typically have cast-iron drain lines buried in or beneath the concrete slab. Florida’s high water table and humidity accelerate the corrosion, so these systems tend to fail earlier than they might in drier climates.
Cast iron corrodes from the inside. The pipe wall thins, the bottom channel rusts away, and the line loses its slope — which is what produces the classic symptoms below.
Signs your cast-iron drains are failing
- Repeated backups in the lowest drains and toilets
- Slow drains across multiple fixtures at once
- Sewer odors inside the home
- Cracked or shifting floor tile, or damp/warm spots on the slab (a possible slab leak)
- Patches of lush or sunken yard over the lateral line
A plumber confirms the condition with a sewer camera inspection, which shows corrosion, bellies (low spots), cracks, and collapse so you can target the repair.
Trenchless lining vs. full excavation
There are two broad paths once cast iron has failed:
- Trenchless lining (CIPP): a resin-saturated liner is inserted and cured in place, forming a new pipe inside the old one. It can often be done through existing access points, avoiding most jackhammering of the slab. It depends on the host pipe still holding its shape.
- Full excavation and replacement: the slab is opened and the old cast iron is dug out and replaced with new PVC. It’s the fallback when lines are collapsed, badly bellied, or otherwise not lineable — and it’s far more disruptive.
What it costs in West Palm Beach
| Approach | Directional planning range |
|---|---|
| Trenchless lining of under-slab cast iron (~2,000 sq ft home) | ~$17,000 |
| Full excavation & replacement (open the slab) | $50,000 – $75,000 |
| Sewer camera inspection / diagnosis | $150 – $600 |
The wide gap is the whole reason to camera the line first: if the cast iron is still structurally sound enough to line, trenchless can save a large multiple over tearing up the slab. If it’s collapsed, excavation may be the only option. Only an inspection tells you which.
Permits & who can do the work
Drain replacement and lining are permitted work in Florida. In West Palm Beach the permit and inspections run through the City building department (the AHJ); homes in unincorporated areas go through Palm Beach County. Historic-district homes (such as Old Northwood and El Cid) may have additional review requirements. Use a Florida state-licensed plumbing contractor — they pull the permit and schedule inspections. Confirm current fees with the City or County.
Check your cast-iron drain situation
Not sure whether you’re looking at lining or full replacement? Use the cast-iron drain tool to understand failure signs and plan your next step for a West Palm Beach home.
Open the cast-iron drain tool →Get the free guide & a no-obligation quote
Send me the plain-English West Palm Beach cast-iron drain planning guide and connect me with a vetted local pro. One email — no spam.
Frequently asked questions
How do I know if my West Palm Beach home has cast-iron drains?
Homes built before about 1972 — common in Old Northwood, Flamingo Park, and El Cid — were typically plumbed with cast-iron drains under the slab. A plumber can confirm with a sewer camera inspection, which also shows how badly the pipe has corroded.
Can my cast iron be lined instead of dug out?
Often, yes. If the host pipe still holds its shape, trenchless lining (CIPP) cures a new pipe inside the old one through existing access points and avoids most slab demolition. If the line is collapsed or badly bellied, excavation may be required. A camera inspection determines which applies.
How much cheaper is trenchless than excavation?
It can be a large difference. As a directional example for a roughly 2,000 sq ft home, lining has been cited around $17,000 versus roughly $50,000 to $75,000 for full excavation and replacement. These are vendor figures for budgeting only — get an inspected quote for your home.
What are the warning signs I should act on?
Repeated backups in the lowest fixtures, multiple slow drains at once, sewer odors, cracked or shifting floor tile, warm or damp slab spots, and lush or sunken patches in the yard over the line. Any of these warrant a camera inspection.
Is a slab leak the same as a cast-iron drain problem?
They’re related but not identical. A slab leak is water escaping a pressurized supply or drain line under the slab; failing cast-iron drains are one common cause in older homes. A plumber can locate the source and tell you whether it’s a drain or a supply-side issue.
Do I need a permit in West Palm Beach?
Yes. Drain replacement or lining requires a permit and inspections through the City of West Palm Beach building department (or Palm Beach County for unincorporated areas), and historic districts may add review. Your licensed plumber normally handles the permit. Confirm current fees with the AHJ.
Want the full breakdown? Read our in-depth Florida plumbing guides →