Under the house, stop 5 of 7

Old galvanized pipe: signs and questions to ask

Galvanized pipe is iron or steel dipped in zinc¹, and in an old house it shows itself as rusty threads and joints, and sometimes weak flow. Ask your utility or a licensed plumber what your service line is made of, since galvanized line can pick up lead from upstream¹.

Go to the spot where the water line enters your house, at the hatch or by the house shutoff, with a fridge magnet in your pocket.

Updated November 4, 2026, Midlands House Walk

Cut end of an old metal water pipe held in a hand, its bore crusted with rust — A cut length of old galvanized water pipe with its open end caked in rust. Look for this when a plumber cuts one out.

Pitted metal elbow with flaking paint and a small dark hole at the bend — A rust hole at a bend in a galvanized well-water pipe, with flaking paint and a leak spot. Bends and threads are good places to start.

What does the outside look like?

Look for: Check the joints you can see from the hatch or at the shutoff. Rust at threads, flaking paint and wet spots are all worth a photo. A fridge magnet sticks to galvanized steel, not to copper or lead.
What it tells you: Rust at one joint can be the first spot of many. Bring your photos to a plumber and ask how much of the run has the same pipe, and what other old pipes the house may hold.

Dull gray pipe at the bottom of a dug hole in a garden, heading toward a house — An old lead service pipe in a dug-out garden in Washington, D.C., not SC. The line from street to house is usually out of sight like this.

What about the line from the street?

Look for: Look at the pipe where it first enters the house. That short visible bit may tell you what’s buried, and a plumber can read it quickly.
What it tells you: EPA says lead pipes are more likely in homes built before 1986, and to ask your utility or a licensed plumber about the service line². Utilities must keep an inventory and notify customers¹, so ask for what it shows. The yard water line covers who owns which part.

Translucent container with a white screw cap beside a kitchen sink — A water sample container on a counter by the sink. Testing is the only sure way to know about lead, according to EPA. AI-generated picture.

Should you test the water?

Look for: Think about who drinks at the kitchen tap, and whether anyone there is a child or someone mixing formula. That shapes how soon to test.
What it tells you: EPA calls testing the only sure way to know about lead, at $20 to $100². Until you know, use cold water only for drinking and formula, and flush before use. Boiling doesn’t remove lead².

Clean copper lines fixed to painted concrete block — New copper pipes up a block wall. New pipe in one spot may mean only part of the house has been changed.

Has it been partly replaced?

Look for: Trace where new pipe meets old. A short new section ending at a rusty joint tells you the old pipe carries on past it.
What it tells you: Weak flow at one sink is first an aerator question: Columbia Water says to take it off and rinse it³. A whole-house drop could be a leak or main break. Then see low water pressure.

What should you ask before agreeing to work?

Three questions cover most of it. Which stretches are galvanized, and how do you know? Is the service line part of this job, or does part belong to the utility? Will you pull a permit? Towns may run their own permits, so who to call helps you check⁴.

Yours to do

Try the magnet at any pipe you can reach, and write down where it sticks.
Ask your utility what its service line inventory says about your address¹.
Rinse the aerator at any weak tap before you worry about the whole house³.

For a licensed pro

Identifying the service line and any buried pipe.
Cutting out and replacing rusted sections. Old threaded joints can break when disturbed, so leave the wrench alone.
Quoting a full or partial replacement. Ask which sections would stay, and why.

Where this comes from

Keep walking (AI picture)No crawlspace? What a slab house shows from outside