Quick Answer:
If your toilet bubbles when it’s storming, it’s most often a sign the sewer system is overloaded and air is being pushed back through drains. Do not flush while it’s happening; wait for the storm to pass and see if the bubbling stops. If bubbling persists after the weather clears, call a plumber.
Why This Happens
Heavy rain increases flow into municipal sewers and private laterals. When the system is full or blocked, pressure changes can force air and gurgling through traps and fixture drains. Clogged vents, roots in the sewer line, or a partial blockage near your home can make the effect worse. You may also notice similar behavior when several fixtures are used at once — this is a different but related drainage-pressure problem, often caused by poor venting or a partial blockage in the building drain.
Two common scenarios are recent plumbing changes that altered trap or vent behavior and surcharge from the public sewer during storms. If you recently had work done, compare symptoms to what you saw before to help diagnose the cause. For example, problems that began right after work could link to installations such as trap changes or vent adjustments; see Toilet gurgles after replacing trap for related signs to look for.
Step-by-Step What to Do
1. Stop using affected fixtures
Avoid flushing during storms and observe recovery; persistent bubbling points to surcharge conditions. Stop using toilets, washing machines, and dishwashers until bubbling stops. This reduces the chance of a backup and limits the amount of water that could be pushed back into the house.
2. Watch and document
- Note which fixtures bubble (toilet, tub, floor drains) and when.
- Check right after the storm eases and then again several hours later to see if things return to normal.
- Take photos or short videos if the problem recurs; this helps a professional diagnose the issue.
3. Check for other signs
- Smells of sewage in the basement or near drains.
- Slow drains or water backing up in sinks when other fixtures are used.
- Water pooling around outside sewer cleanouts or manholes if accessible.
4. Avoid DIY fixes that can make it worse
Do not use strong chemical drain cleaners if sewage is present, and do not attempt to force blockages with powered equipment unless you are trained. If you suspect a blocked lateral or sewer surcharge, professional inspection is safer.
If you notice the bubbling mainly when several fixtures are used simultaneously, it often points to shared venting or partial blockage — compare symptoms to Toilet bubbles when multiple fixtures used to see if the pattern matches.
What Not to Do
- Don’t flush during storms if bubbling occurs—surcharge risk; a plumber is appropriate.
- Do not pour chemical drain cleaners into a system that may be backing up — they can splash and cause harm.
- Do not try to open municipal manholes or perform sewer line excavation yourself.
When to Call a Professional
- If bubbling continues after the storm has passed and normal flow hasn’t returned.
- If sewage backs up into fixtures, or you can smell sewer gas indoors.
- If multiple fixtures are affected or you see water pooling near sewer cleanouts or outside drains.
A licensed plumber can camera-inspect the lateral, test vents, and determine whether the issue is on your property or in the public sewer.
Safety Notes
- Sewage contains pathogens. Avoid contact and do not handle backups without gloves and proper protection.
- If you smell strong sewer gas, ventilate the area and leave if the odor is overwhelming; sewer gas can be hazardous in high concentrations.
- Keep children and pets away from affected drains and any standing sewage.
Common Homeowner Questions
- Why did this start only during heavy rain? — Storms can overload the sewer system or reveal partial blockages that don’t show up during dry weather.
- Will a plunger fix this? — No. A plunger won’t resolve a sewer surcharge or a blockage beyond the trap; avoid plunging during active bubbling.
- Can the municipality fix it? — If the issue is a public sewer surcharge or main blockage, the municipality is responsible; a plumber can help confirm where the problem lies.