Water never moves in floor drain

Close-up of a floor drain with water sitting motionless under the grate

Quick Answer:

If you test the laundry drain and notice water won’t move from the nearby floor drain, start with simple, non-destructive checks. Remove the grate and trap cover, look into the trap with a flashlight for a solid blockage, and feed a flexible inspection tool or fish tape 6–10 feet to feel for resistance. Slowly pour 1–2 gallons of water to see whether the trap refills and then drains. Pay attention to any gurgling from other fixtures—this can mean a partial blockage further down the line.

Why This Happens

When a floor drain doesn’t clear, the issue is usually one of these:

  • Something stuck in the trap near the drain opening (hair, small objects, buildup).
  • A partial or full blockage in the lateral line that carries water to the main sewer.
  • A dry or damaged trap that won’t hold water and so allows air to prevent normal flow.
  • Vent or sewer issues farther down the line that cause pressure problems and slow drainage; you may notice gurgling or slow drainage elsewhere.

Also check for related symptoms like slow drains in sinks or toilets and odors. These clues help locate whether the problem is at the local trap or deeper in the lateral line. If you’ve seen issues like **Standing water in basement drain** or odd nighttime-only pooling, treat them as part of the same drainage system when diagnosing.

Step-by-Step What to Do

1. Access the drain — remove grate and trap cover

  • Put on gloves and eye protection.
  • Remove the floor grate and any trap access cover. Keep screws or clips in a safe place.

2. Look inside the trap with a flashlight

  • Shine a bright flashlight down the opening. Look for a solid obstruction you can see and safely remove by hand or with long-nose pliers.
  • If you see sewage or heavy buildup, avoid reaching in; use a tool or call a pro.

3. Feed a flexible inspection tool or fish tape 6–10 feet

  • Use a flexible drain inspection probe, sewer snake, or fish tape. Feed it straight for 6–10 feet to check for resistance.
  • If you meet firm resistance close to the trap, the clog is likely local. If it goes farther before feeling resistance, the problem is deeper in the lateral line.
  • Do not force a rigid tool; feel for give and back out if you hit solid resistance to avoid damaging pipe joints or PVC.

4. Perform a slow water refill test (1–2 gallons)

  • Pour 1–2 gallons of water slowly into the drain, watching whether the trap refills and then drains away. Pouring slowly helps the trap refill without pushing a blockage deeper.
  • If the water sits and doesn’t drain, the trap or lateral line is likely blocked. If the trap refills then drains, you may have had an airlock or minor issue that cleared.

5. Listen for gurgling and check other fixtures

  • Have someone run a sink or flush a toilet while you listen at the drain. Gurgling from the floor drain or other fixtures suggests a partial blockage farther down the system.
  • Note which fixtures show symptoms—this helps a plumber locate the problem if needed.

What Not to Do

  • Avoid repeatedly pouring boiling water into plastic drains; extreme heat can deform PVC parts.
  • Do not force rigid tools or metal rods into the pipe—these can crack or dislodge PVC fittings.
  • Don’t use powerful chemical drain cleaners in a suspected sewer-line blockage; they can be harmful and often won’t reach the clog.
  • Do not ignore strong sewer gas or sewage backing up—these are signs for immediate professional help.

When to Call a Professional

  • Strong sewer gas odors inside the house.
  • Multiple fixtures are slow or backing up at the same time.
  • You cannot locate or clear the obstruction after the basic checks above, or you encounter sewage that you don’t want to handle yourself.
  • If a camera inspection, auger, or professional snake is needed to find or remove a deep clog.

Safety Notes

  • Wear gloves, eye protection, and work clothes you can wash. Sewage and buildup carry bacteria.
  • Ventilate the area if you smell sewer gas. Do not light matches or use open flames—methane can be present.
  • Wash hands and tools after work. Disinfect any surfaces that contact wastewater.
  • If you feel unwell after exposure or see evidence of a major sewer problem, stop work and call a professional.

Common Homeowner Questions

  • Why is the floor drain still full after I poured water? — A nearby clog or a damaged trap can hold water; an inspection tool can help find the obstruction.
  • Is a small gurgle a big problem? — Not always, but gurgling often means a partial blockage; monitor other fixtures and take the slow test described above.
  • Can I use a plunger on a floor drain? — You can try a plunger for a local, small blockage, but be cautious—cover nearby drains and watch for sewage backup.

More in this topic

For more related fixes and similar symptoms, see Standing Water in Floor Drain.

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