Grease interceptor pumping is the process of removing accumulated fats, oils, grease (FOG), and settled solids from a large in-ground or below-grade interceptor, typically using a vacuum truck. Unlike small under-sink grease traps, interceptors serve higher-volume kitchens and are usually subject to more formal local FOG program requirements, including scheduled pump-outs and documented manifests.
What Happens During a Pumping Service
A licensed technician arrives with a vacuum truck, opens the interceptor's access lids, and removes the full contents — FOG layer, wastewater, and settled solids — rather than skimming only the surface grease. Many local ordinances require this "full pump-out" approach (removing everything, not partial skimming) because partial cleaning leaves solids behind that reduce the interceptor's effective capacity. After pumping, the technician typically rinses the interior, inspects baffles and tees for damage, and reassembles the unit. The removed waste is hauled to a permitted disposal or rendering facility.
How Often Interceptors Need Pumping
Frequency depends on interceptor size, kitchen volume, and local requirements, but most local FOG programs set either:
- A fixed maximum interval (commonly every 1 to 3 months for active food service establishments), or
- The 25% rule — pump when FOG plus solids reach about 25% of the interceptor's liquid depth, whichever comes first.
Because these thresholds are set locally rather than federally, the exact frequency your establishment must follow depends on your municipal wastewater authority's ordinance. EPA's National Pretreatment Program authorizes local control authorities to impose these kinds of requirements on FOG-generating businesses, but it does not itself set a universal pumping interval.
Interceptor Pumping vs. Small Grease Trap Cleaning
Grease interceptors are larger — often 500 to 2,000+ gallons and installed outside or under a parking area — compared to small point-of-use grease traps under a three-compartment sink (typically 20 to 50 gallons). Interceptor pumping requires a vacuum truck and is usually performed by a commercial grease trap service company rather than in-house kitchen staff, while small traps can sometimes be cleaned by staff between professional services (subject to local rules). If you're unsure which type of device your establishment has, your local wastewater authority or the equipment manufacturer's documentation can clarify.
What a Manifest Documents
Many municipal FOG programs require haulers to complete a trip ticket or manifest for each pumping service. Typical manifest fields include the facility name and address, date and time of service, volume of waste removed, the hauler's permit number, and the name of the disposal facility receiving the waste. This documentation gives the local wastewater authority a paper trail showing that FOG-generating businesses are maintaining their interceptors on schedule — see our companion piece on FOG manifest requirements for more detail. Facilities are often required to keep copies of these manifests on-site for a set retention period in case of inspection.
Cost Drivers for Interceptor Pumping
Pricing depends primarily on:
- Interceptor size — larger units hold more waste and take longer to pump.
- Waste volume and consistency — heavily solidified or aged FOG can take longer to remove and may require additional labor.
- Disposal fees, which vary by region and by the receiving facility.
- Travel distance and local labor rates.
As a general range, interceptor pumping often costs several hundred dollars per visit for mid-size units, with larger or harder-to-access interceptors costing more. Emergency or off-hours service (e.g., after a backup) typically costs more than scheduled maintenance. Because interceptors that are neglected accumulate more waste, letting a unit go past its scheduled interval can increase the cost of the eventual pump-out.
Why Skipping Scheduled Pumping Is a Risk
An interceptor that isn't pumped on schedule loses effective retention capacity, allowing more FOG to pass through into the sewer lateral and municipal collection system. This is one of the more commonly cited contributors to sewer blockages and overflows in areas with concentrations of food service establishments, which is part of why many local FOG programs conduct periodic inspections of high-risk facilities and can issue fines or suspend a facility's discharge authorization for noncompliance.
How to Choose and Verify a Grease Trap Service Company
When hiring a company for interceptor pumping:
- Verify they appear on your municipality's permitted hauler list. Most FOG programs maintain and publish this list; ask your local wastewater authority if you can't find it online.
- Ask for a sample manifest so you know what documentation you'll receive after each service — you may need to retain these records for inspections.
- Confirm they perform a full pump-out, not a partial skim, in line with your local ordinance.
- Check where they dispose of waste and confirm the receiving facility is permitted to accept it.
This directory publishes independent, source-backed public records about grease trap service providers; it does not certify, license, or endorse any company. Verify hauler permitting directly with your local wastewater authority before scheduling service.
FAQs
Can I pump my own grease interceptor? Some jurisdictions allow facility staff to perform limited maintenance, but full pump-outs generally require a licensed, permitted hauler with vacuum truck equipment and access to approved disposal. Check local requirements before attempting this yourself.
How long does interceptor pumping take? A typical service for a mid-size interceptor takes roughly 30 minutes to a couple of hours, depending on size and accessibility, though larger commercial systems can take longer.
What if my interceptor is overdue for pumping? Contact a permitted grease trap service company as soon as possible. An overdue interceptor increases the risk of backups and potential fines from your local wastewater authority, and delaying service can also increase the cost of the eventual cleanout.