Standing water after winterization

Quick Answer:

If you find standing water in a garage floor drain when you inspect in spring, start with a careful visual check and simple tests before assuming a cracked trap or lateral. Remove the grate, look for ice or hairline cracks around the drain and concrete, and slowly pour a small amount of lukewarm water to see whether it drains or leaks outside the pipe. If you notice persistent leakage, water tracking into the foundation, or clear pipe damage, stop and call a professional. For related seasonal patterns see Standing water only in winter and if you were away all winter see Standing water after vacation.

Why This Happens

Ice left in the trap or pipe can melt slowly and create temporary standing water rather than a continuous flow.
Freeze expansion can cause hairline cracks in the plastic or cast‑iron trap flange, the lateral, or in nearby concrete around the drain.
Blocked vents or downstream clogs can slow drainage so meltwater pools near the drain opening.
Soil shifting or settling can change pipe slope and allow water to collect rather than run away.

Step-by-Step What to Do

1. Prepare and stay safe

Put on gloves and use a flashlight. Keep towels or a small container handy for water.
Do this work during daylight if possible so you can see small cracks and wet tracks in the concrete.

2. Remove the grate and look for ice remnants

Carefully lift the drain grate—use plastic pry tools or a screwdriver with a cloth to avoid damaging the flange.
Look inside for chunks of ice, slushy water, or debris. Ice in the trap is a common cause of spring standing water.

3. Check for hairline cracks around the drain flange and surrounding concrete

Use your flashlight to inspect the flange edge and the concrete around it for thin cracks or grout separation. Hairline cracks can let meltwater escape under the slab or into voids.
Wipe the area dry with a towel and watch for new wetting as you run the test below.

4. Slowly pour lukewarm water into the drain to test flow and look for external leaks

Use a jug and pour a small amount (a liter or so) of lukewarm—not hot—water slowly into the drain.
Watch the outside of the flange, the concrete joint, and the floor under the drain for any sign of water appearing. If water shows up externally, stop the test and document the location.

5. Inspect any visible exposed piping for frost damage

Check exposed trap, stub-outs, or lateral runs you can see for white frost patterns, bulges, flaking, or small visible cracks.
Frosted or crazed plastic and rusted, cracked metal are signs freeze damage may have weakened the pipe.

6. Test nearby fixtures for proper venting and flow

Run a sink, flush a toilet, or pour water into another floor drain and listen for gurgling or slow drainage. Gurgling means venting or downstream flow problems.
If multiple fixtures are slow, the issue may be a downstream clog or venting problem rather than a single cracked trap.

What Not to Do

Do not pour hot water into a cold drain — rapid temperature change can crack plastic or concrete.
Do not force ice out with metal tools that can chip or crack the drain assembly or concrete.
Do not dig up or pry at suspected lateral lines yourself; if you suspect cracked piping, persistent leakage, or water is tracking into the foundation, call a pro rather than attempting major excavation or repairs.

When to Call a Professional

Evidence of a cracked trap or lateral (visible cracks, water appearing under the slab, or water coming up outside the flange).
Persistent leakage after basic tests, or if water is tracking toward the foundation walls or down into a crawl space.
Multiple fixtures show slow drainage, strong sewage odors, or you find contaminated-looking water—these often require camera inspection and trained repair.
If you’re unsure how to proceed or the repair would require breaking concrete or replacing pipes, a licensed plumber can do a CCTV inspection and advise repair options.

Safety Notes

Stop testing immediately if you see water appearing where it shouldn’t or the floor becomes slippery.
Avoid electrical hazards—don’t stand in pooled water near plugged-in equipment; shut off power if necessary.
Wear gloves and eye protection when handling debris or clearing the grate. Meltwater can carry trapped dirt and contaminants.
Use only lukewarm water for thawing tests; rapid heating or hot water can make cracks worse.

Common Homeowner Questions

Q: Could this be just leftover ice melting?
A: Yes. Ice in the trap or immediate pipe often causes temporary standing water as it melts.
Q: If the water drains slowly, should I try a drain snake?
A: You can only try minor snaking on accessible lines; stop if you meet firm resistance and call a plumber for deeper clogs.
Q: Will I see obvious cracks if a pipe is freeze‑damaged?
A: Not always—hairline cracks or damage under concrete may be hidden. A professional camera inspection finds hidden breaks reliably.