When a grease trap smells like sewage, it’s more than just unpleasant — it’s a warning sign. Whether you own a restaurant, coffee shop, or commercial kitchen, bad odors from a grease trap can drive away customers, frustrate staff, and even trigger health code violations.
So, why does this happen? And more importantly, what can you do to fix it?
This guide breaks down the common causes of grease trap odors, how to stop the smell, when to call a plumber, and how preventative maintenance can keep your business safe and smelling fresh.
What Is a Grease Trap (Quick Refresher)?
A grease trap (or interceptor) is a plumbing device that keeps fats, oils, and grease (FOG) out of sewer lines. Wastewater enters, solids settle at the bottom, grease floats to the top, and cleaner water exits into the sewer.
Learn more about the basics on our grease trap services page.
Without regular cleaning, however, that “layer cake” of waste starts to rot. That’s when smells hit.
Why Does My Grease Trap Smell Like Sewage?
- Built-Up Grease and Solids – If the trap isn’t pumped often enough, waste decomposes and smells.
- Clogged or Slow Drains – Backed-up food and grease trap odors inside pipes. See our blog on the hidden dangers of ignoring slow drains.
- Dry Traps or Vents – Like a dry sink trap, it can allow sewer gases to escape.
- Poor Ventilation – Inadequate venting makes odors linger inside your building.
- Cracks or Leaks – Damaged traps or pipes may leak foul smells.
Health and Safety Risks of Odors
- Bacteria growth – Rotting FOG produces harmful bacteria.
- Air quality issues – Sewer gases can cause headaches or nausea.
- Health code violations – Odors can trigger citations and fines.
- Customer experience – No one wants to dine or drink coffee near a sewage smell.
The EPA Pretreatment Program explains how grease trap failures harm both health and local wastewater systems.
How to Get Rid of Grease Trap Odors
1. Schedule Professional Cleaning
Pumping removes the FOG layers that create odor. Most traps need cleaning every 1–3 months. 👉 Book service through our commercial drain cleaning page.
2. Inspect with a Camera
A camera line inspection helps find clogs, cracks, or issues causing odors.
3. Check Ventilation
Confirm your system vents properly to prevent gas buildup.
4. Repair or Replace Damaged Traps
Cracked or rusted traps may need plumbing repair or pipelining/repiping.
5. Use Preventative Maintenance
Don’t wait for odors. Enroll in the Solid Care Plan ($144/year) for routine inspections and service.
How Often Should a Grease Trap Be Cleaned?
- Small cafés: Every 1–2 months
- Busy restaurants: Every 2–4 weeks
- Large facilities: Weekly or as required
Many counties require documented cleaning logs. Skipping can mean fines.
Preventing Future Odors
- Scrape food waste into trash cans before washing.
- Train staff on what not to pour down sinks.
- Use strainers to catch solids.
- Schedule inspections and cleanings regularly.
- Get preventative plumbing maintenance to avoid surprises.
See more in our blog on year-round plumbing maintenance.
Signs You Need Immediate Service
- Frequent backups in sinks or dishwashers
- Standing water near drains
- Gurgling noises in pipes
- Odor complaints from staff or customers
Don’t wait. Contact us today.
DIY Fixes vs. Professional Help
Some try chemicals or home remedies. These don’t solve the issue and can damage pipes.
We tested several “hacks” — see what really works in our blog on drain cleaning hacks that worked.
Professional service ensures full cleaning, inspection, and compliance.
FAQ: Grease Trap Smells Like Sewage
Why does my grease trap smell so bad?
Built-up FOG and food waste decompose, releasing sewer gases.
Can I pour chemicals in the trap?
No — they mask smells temporarily and corrode pipes.
How often should my trap be pumped?
Most need cleaning every 1–3 months, busy kitchens even more often.
What if the smell comes back quickly?
Likely ventilation or damage. Consider plumbing repair services.
Do inspectors check grease trap odors?
Yes. Odor complaints can lead to citations and fines.
Final Thoughts: Don’t Ignore the Smell
If your grease trap smells like sewage, it’s a red flag. Ignoring it risks clogs, fines, and unhappy customers.
Schedule regular cleaning, inspect for damage, and keep a maintenance plan in place to protect your business.
Contact Solid Plumbing & Drains for a free inspection and odor solution today.
