Smelly Grease Trap Essentials

Why your grease trap smells

Have you ever been behind a restaurant and smelled something akin to rotten eggs, vinegar and ammonia?  If you have, you were whiffing a smelly grease trap or grease interceptor that was not functioning properly. If you are a restaurant owner a smelly grease trap is very bad news for you and your customers.

What is a grease trap or grease interceptor?

Grease traps exist to prevent the contamination of our waterways. A grease trap is a gravity device that separates the fats, oils, grease, and solids (FOGS), preventing them from entering the city sewer lines.  It separates grease and solid waste from the kitchen. When waste water from the kitchen enters the trap, the grease settles on the top, solids in the bottom and waste water in the middle, which separates the grease from the solids.

An interceptor works similarly but is much larger, typically 500+ gallons and is installed below ground.

Grease Interceptor

Grease trap pumping

If traps and interceptors are not regularly pumped and properly maintained they back up into your kitchen and the result is much like the backing up of a septic system into a house. Those terrible grease trap smells can come from several sources

• broken gaskets around manhole covers
• a dry trap or interceptor
• a full trap or interceptor
• a broken p-trap
• a trap installed backwards (yes, it happens!)
• clogged pipelines
• a trap or interceptor at more than 25% FOG content

A severe grease trap problem can damage your business for much longer than the time it takes to fix it. Think of the lost revenue, lost customers and damage to your reputation.

Grease traps need to be pumped whenever the contents are above 25% of capacity. This could be weekly or every 3 months depending on the size of the tank and the volume of FOGs and water. Traps and interceptors should never be left dry. This is why “pump and return” is allowed in many municipalities. That means the traps are pumped but the grey water is returned to the trap to prevent drying and grease trap smells.

Nearly every municipality has rules for maintaining traps and severe fines for violations.

Every restaurant needs professionals versed in the regulations and the tools required to pump, evaluate and repair traps and interceptors.

Grease trap maintenance

Traps must be cleaned according to a schedule defined in municipal guidelines and regulations. Grease traps contain grease, fats, oils and food solids in the grease trap compartments. 

Grease rises to the top and is pumped out with a mechanical pump that is sometimes portable and sometimes connected to a truck that is specially designed for trap pumping and cleaning. 

After liquid is removed, solidified grease on the walls and baffles is scraped. The trap is cleaned and rinsed with soap and hot water. 

Tips for maintaining your grease traps/interceptors

1. Hire a professional. This is always the best choice when it comes to trap/interceptor maintenance. They provide excellent service, and will help keep you compliant with state and federal laws, and they’ll prevent you from having to handle a smelly grease trap!
2. Have your trap/interceptor cleaned regularly. Depending on the size of your grease trap or interceptor, you may need to clean it more than once or twice a year. Their expertise will determine how often you need to pump and clean. Have your lines jetted twice a year. Line jetting is a very effective method of pipe cleaning, and is  essential to preventive grease trap/interceptor maintenance. A hose with powerful jets is inserted into the (external) plumbing and water is forced out, in a circular motion, at high pressure. This is one of the most effective ways to completely remove debris from pipe walls and prevent smelly grease traps.
3. Make sure your trap/interceptor is secure. Grease trap/interceptor lids should be constructed of a sturdy material and secured by a locking mechanism – protecting you, your staff and customers.