Under the house, stop 1 of 7

What to look for from the crawlspace hatch

Crawl space plumbing gives most of its clues from the hatch: wet dirt under a joint, fallen insulation, the type of pipe, and where a valve sits. Bring a flashlight and stay at the opening. Your job is to look, then pass on what you saw.

Kneel at the crawlspace hatch with a flashlight, and keep your body outside the opening.

Updated November 4, 2026, Midlands House Walk

Stay out if you see standing water, sewage or live wiring. A whiff of gas or propane at the hatch changes the job: walk away from the house first, leave the switches alone, make no calls indoors, and phone 911 and the gas company or propane supplier once you’re outside⁵.

Flashlight beam crossing plastic sheeting toward brick piers and a wrapped duct under a floor — The beam from the hatch picks out plastic over the dirt, brick piers and wrapped lines. Your own view may be rougher. AI-generated picture.

Open access panel showing bare dirt and a white plastic drain pipe with a tee — Through an open panel: bare dirt, a white plastic drain with a tee, and wires and pipes along the joists.

Is the dirt dry under the joints?

Look for: Run the beam along the pipe and stop at each tee or joint. A dark patch directly below a fitting is the thing to photograph.
What it tells you: A wet patch below a fitting suggests a drip, and EPA puts fixing leaks and seepage among the main ways to control crawlspace moisture¹. Below a drain, treat it as possible sewage and go to water or sewage under the house.

Gray foam sleeves with taped seams on water lines running beside floor joists — Gray foam sleeves with taped joints on water lines along the joists. Look for gaps and sagging pieces in yours. AI-generated picture.

Is the foam still on the pipes?

Look for: Follow each line as far as the light reaches. Bare stretches, hanging sleeves and foam lying on the dirt are easy to spot from here.
What it tells you: Clemson advises insulating both hot and cold lines in crawlspaces². Bare stretches are where a hard cold spell may find you, and wrapping the pipes covers what matters.

Flexible gray tubing held to wooden joists, with copper rings at the joints — Flexible gray pipe with copper crimp rings on wooden joists. The color is a reason to ask about it, not an answer. AI-generated picture.

What are the pipes made of?

Look for: Note the color and whether the pipe is flexible or rigid. Flexible gray, silver or blue is one group. Rough threaded metal with rust is another.
What it tells you: Flexible gray, silver or blue pipe could be polybutylene, which a plumber should confirm³. See gray plastic pipe for that and old galvanized pipe for the rusty kind.

Dark cast-iron pipes seen through a cut opening in a wall beside a wooden stud — Cast-iron drains exposed through an opening in a wall. A heavy, dark pipe like this under your floor is a drain, not a water line.

Which way does the big pipe go?

Look for: Find the fattest pipe you can see and note which wall it heads for. You only need the direction, so take it from the hatch.
What it tells you: On a septic house, Clemson suggests tracing the 4-inch sewer pipe outward from the crawlspace to find the tank⁴. The wall it leaves through is your start for finding the septic tank.

Water line with a yellow-handled brass valve running down white plastic sheeting — A water line with brass valves running down a wall covered in white plastic. A lever or wheel like these may be a shutoff.

Can you see a valve from here?

Look for: Look where the water line enters the house, and on the foundation wall nearest the street. A lever or small wheel is what you want.
What it tells you: Clemson lists near the foundation, at the meter and above the water heater as common shutoff spots². A valve you can only reach by crawling is worth raising with a plumber, and the house shutoff stop shows the other places to check.

How close do you need to get?

Close enough to see, and no closer. Everything on this page can be read from the opening with a good light. If something is out of sight around a pier, that is a question for whoever goes under, and old pipes lists what to ask.

Yours to do

Look in from the hatch in daylight, and take phone photos of anything wet or hanging loose.
Write down the pipe types you can see and which wall each main line runs toward.
Note the date and the weather, so you can compare the same view after a heavy rain.

For a licensed pro

Tracing and repairing anything wet under a fitting, since that work happens inside the crawlspace.
Confirming what a pipe is made of when the look alone doesn’t settle it.
Replacing fallen insulation around wiring or in tight runs you can’t reach from the opening.

Where this comes from

Keep walkingWhy a Midlands crawlspace stays damp