Quick Answer:
Standing water around a floor drain grate usually means something is slowing the water entry at the grate or immediately below it — not always a deep, under-floor clog. Start by removing debris at the grate, do a small measured pour to time drainage, check whether a trap primer or nearby fixtures are affecting the level, and look for signs the floor has settled. These quick checks will tell you whether the problem is surface-level or needs a plumber.
Why This Happens
- Debris or hair trapped under the grate can hold water around the rim and slow drainage.
- A partially blocked trap or the drain inlet weep holes can keep water from flowing freely.
- A malfunctioning trap primer can either leave the trap too full or fail and let odors in; if it’s stuck open it may change how water pools at the grate.
- Floor settling or a low spot around the drain changes slope and lets water collect instead of flowing in.
- Shared drain lines: when other fixtures run they can change flow and cause standing water or slow drainage.
- Occasionally, related issues show other signs like a gurgling noise at night — if you hear that, it can point to a line venting or partial blockage that affects multiple drains. See **Drain Makes a Loud Glugging Sound at Night** for more on that symptom.
Step-by-Step What to Do
1. Check for debris under the grate
Put on gloves and remove the grate. Look down with a flashlight and remove hair, soap scum, or other debris you can reach. Clean the grate itself. Many times this is enough for water to stop pooling.
2. Test the drain with a measured pour
Pour a known small amount of water (about 1 quart / 1 liter) directly into the drain and time how long it takes to disappear. Note whether the drain takes a few seconds, a minute, or does not drop at all. Repeat the test after clearing debris to see if there’s an improvement.
3. Verify the trap primer (if present)
If the drain has a trap primer (a small device that keeps the trap filled), check for signs it’s stuck open or leaking into the drain. A primer that runs continuously can leave water pooling; one that isn’t working may cause odors but not pooling. If you’re unsure how the primer should operate, note the behavior and tell the plumber.
4. Check slope and settling signs
Look for cracks, gaps in tile grout, or a noticeable low spot around the drain. Floor settlement creates pockets where water collects instead of flowing to the drain. If the floor looks uneven around the drain, that suggests a surface grading issue rather than a hidden pipe clog.
5. See if standing water changes after other fixtures run
Run a nearby fixture briefly (a sink or shower) and watch the floor drain. If the standing water level rises, drops quickly, or backs up when another fixture runs, the issue may be in the shared line. If nothing changes, the problem is likely local to the drain area.
6. Consider a deeper inspection only if needed
If the measured pour backs up or does not clear and you cleared visible debris, a snake or camera inspection may be appropriate. Don’t remove the drain body or dig into flooring without a clear plan — these steps can make repairs more invasive. If you notice unusual material coming up (like black residue), that’s a sign to escalate; **Drain Has Black Slime Coming Up** covers what that can mean.
What Not to Do
- Do not chip away flooring or remove the drain body without a plan and the right tools — these actions can damage tiles and the drain assembly and may make a small problem much worse.
- Avoid pressure-washing water into the drain to try to force it clear — that can push debris deeper, spread contamination under the floor, and create other problems.
When to Call a Professional
- If the measured pour consistently backs up or never clears after you remove debris.
- If water levels rise when other fixtures run, suggesting a shared-line blockage.
- If you find evidence of sewer gas, persistent odors, or black slime coming up from the drain.
- If the floor shows structural settling around the drain or if you’re unsure how to access a trap primer or drain body safely.
- If you’re uncomfortable performing the inspection steps — a plumber can do a camera inspection and safely remove the drain body if needed.
Safety Notes
- Wear gloves and eye protection when reaching into drains; debris can be sharp or contaminated.
- Do not mix chemicals if you try cleaners. Strong chemicals can create dangerous fumes and damage pipe finishes.
- Avoid aggressive mechanical actions (chisels, hammers) on finished floors — they risk injury and costly repairs.
- If electrical outlets or appliances are near the floor drain, keep water away and turn off power to those circuits before working in a wet area.
Common Homeowner Questions
- Q: Is the standing water a health hazard?
A: It can be unsanitary if it contains organic debris or sewer material. Clean and dry the area after addressing the cause. - Q: Will pouring bleach or drain cleaner fix it?
A: No—chemicals often don’t clear the mechanical blockage at the grate and can be harmful. Clear debris first and consult a pro for persistent issues. - Q: How long should I wait before calling a plumber?
A: If a simple grate clean and a measured pour don’t improve drainage within a day or if water backs up when other fixtures run, call a plumber.