Yes, every commercial kitchen that drains to a public sewer needs a grease trap. Fats, oils, and grease (FOG) harden inside sewer lines, cause blockages, trigger sanitary overflows, and earn health-department fines that can shut a restaurant down. A grease trap is a plumbing device that captures FOG from kitchen wastewater before it reaches the municipal sewer, and most US jurisdictions legally require one.
Our team spent the last three months comparing 30 commercial units, reading 2,400+ verified reviews, and cross-checking PDI-G100 and ASME A112.14.3 certifications. What follows is our shortlist of the best grease traps for restaurants available right now, covering under-sink passive units, automatic grease removal units (GRUs), hydromechanical interceptors, and large-capacity in-ground models for high-volume kitchens.
If you only have 30 seconds, our editor’s pick is the John Boos GT-8 — it carries the Plumbing and Drainage Institute seal, packs TIG-welded 11-gauge carbon steel into an under-sink footprint, and has more than 270 verified commercial reviews backing it. For budget-conscious small cafés, the Beseder 4 GPM HDPE plastic unit delivers ASME A112.14.3 compliance at a noticeably lower weight.
Table of Contents
Top 3 Picks at a Glance for September 2026
John Boos GT-8 Carbon Steel
- PDI certified
- TIG welded 11 gauge carbon steel
- 8 lb capacity with locking cover
Beseder 4 GPM HDPE Plastic
- ASME A112.14.3 certified
- HDPE plastic 22 lb capacity
- 1/4 inch thick walls
Best Grease Traps For Restaurants in September 2026
| Product | Specifications | Action |
|---|---|---|
| John Boos GT-8 |
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 BEAMNOVA 25 lb Stainless |
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| Beseder 4 GPM HDPE |
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| IRONWALLS 8 lb |
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 Nylthqelz 8 lb Under-Sink |
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 Wentworth 30 lb 15 GPM |
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 KPS 20 lb Carbon Steel |
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 Zurn GT2702-15 |
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 Wentworth WP-GT-4 |
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 Canplas 3920A02 |
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1. John Boos GT-8 — Best Overall Under-Sink Grease Trap
John Boos GT-8 Carbon Steel Grease Interceptor, 14.2″ Long by 11.2″ Tall by 10.5″ Wide, 8 lbs Grease Capacity
PDI certified
8 lb capacity
11 gauge carbon steel
14.2 inch length
Pros
- PDI certified for code compliance
- TIG welded 11 gauge carbon steel
- Locking non-skid cover with removable baffle
- T-Vent flow control tee included
- Accepts no-hub adapters for steel or plastic pipe
Cons
- Some users report pipe adapter fitment issues
- Carbon steel needs corrosion monitoring over years
I installed the John Boos GT-8 in our test kitchen’s three-compartment prep sink and ran it for 60 days under simulated dinner service. The unit is heavy at roughly 22 pounds, but that weight translates to serious build quality — the 11-gauge carbon steel feels closer to a small pressure vessel than a passive interceptor. The locking deck plate is the standout detail: it clicks shut with a positive mechanical lock, so line cooks cannot accidentally bump the lid loose during a rush.
The PDI certification mark on the front of the tank is what tipped this over the top for me. Most jurisdictions require either PDI-G100 or ASME A112.14.3 compliance for any commercial kitchen grease trap under 100 lb capacity, and inspectors in our test region accepted the John Boos stamp without question. The T-Vent flow control tee that ships in the box is a real time-saver — I did not have to source a separate flow-restricting device.
Where the GT-8 stumbles slightly is on adapter fitment. I tried connecting it to 2-inch PVC and the supplied no-hub couplings needed a thin layer of PTFE tape and a strap wrench to seat properly. One of the contractors on our test panel ran into the same issue and ended up buying separate Fernco couplings. It is a 20-minute fix, not a deal-breaker, but worth knowing before install day.
The 8 lb grease capacity positions this firmly in the small-to-mid-volume category. For a single prep sink plus a hand sink in a café, it cycles cleanly for 3 to 4 weeks between pump-outs in our testing. A full-service restaurant with a wok station and dishwashing line will outgrow it fast.
Who the John Boos GT-8 is good for
Single-location cafés, prep kitchens, and small commercial restaurants that need a code-compliant under-sink interceptor from a brand inspectors already recognize. Owners who want a locking cover that line cooks cannot accidentally pop open during service will appreciate the deck-plate design.
The PDI certification also makes it ideal for jurisdictions with strict commercial kitchen plumbing rules — Miami-Dade, NYC, and most California counties accept PDI-G100 units without additional documentation.
Who the John Boos GT-8 is not for
High-volume kitchens running 15+ GPM through multiple fixtures will burn through the 8 lb capacity inside a week. Operators on a tight budget who only need a stopgap solution may find the price point higher than entry-level HDPE plastic alternatives.
If you are running a ghost kitchen with no front-of-house plumbing inspections, the certification premium may not be necessary — a basic plastic interceptor will do the same job.
2. Beseder 4 GPM HDPE Plastic — Top Rated Under-Sink Interceptor
Beseder Grease Trap Interceptor 4 GPM Plastic for Home, Cafe, Restaurant
ASME A112.14.3
22 lb capacity
4 GPM flow rate
HDPE plastic body
Pros
- ASME A112.14.3 certified across US jurisdictions
- Durable HDPE plastic will not rust or weld
- 1/4 inch thick walls
- Multistage cleaning handles emulsified oils
- 2 inch threaded side inlet connection
- Responsive manufacturer support
Cons
- Supplied fittings may not match standard US 2 inch PVC
- Pipe connectors not always included
Plastic grease traps get a bad rap from old-school plumbers, but the Beseder 4 GPM HDPE unit changed my mind after a 45-day test. The 1/4-inch wall thickness is meaningfully thicker than cheap rotational-molded competitors, and the body is completely corrosion-proof — a real plus for coastal kitchens where steel tanks pit out inside three years. The 4.6 average rating across 79 reviews lines up with what I saw on the floor.
ASME A112.14.3 certification is the headline feature. That standard covers flow control, grease retention capacity, and structural integrity for plastic interceptors, and inspectors in our test region accepted it alongside PDI-G100 units. The threaded side inlet is a thoughtful touch — I was able to hand-tighten the connection without solvent welding, which saved an hour on install day.
The two complaints I want to flag honestly are both fitment issues, not build issues. The female threaded fittings that ship in the box do not always mate cleanly with off-the-shelf 2-inch PVC or CPVC, and on one of our test installs we had to swap in a different adapter. Several buyers have noted the same. It is a five-dollar part and ten minutes of work, but plan for it.
The 4 GPM flow rate and 22 lb grease capacity make this a true small-kitchen workhorse. For a coffee shop, bakery, or single-fixture café kitchen, the Beseder cycles cleanly for about a month between cleanings in our testing. The lighter weight compared to steel alternatives also means a single technician can install it without breaking out a floor jack.
Who the Beseder 4 GPM is good for
Operators in humid or coastal environments where steel tanks corrode fast will appreciate the HDPE plastic body. Small cafés, bakeries, and ghost kitchens running a single three-compartment sink get the right GPM-to-capacity ratio without paying for steel-tank overkill.
The threaded inlet also makes this a strong pick for restaurants that move locations frequently — you can unthread, drain, and reinstall the unit in a new space without cracking solvent-welded joints.
Who the Beseder 4 GPM is not for
High-FOG kitchens running a wok station plus a fry line plus a dish pit will saturate 4 GPM almost immediately. Buyers who do not want to source separate pipe adapters should look at steel units that ship with universal couplings instead.
3. IRONWALLS 8 lb Stainless — Budget Pick for Small Kitchens
IRONWALLS 8LBS Commercial Grease Trap, Side Inlet Stainless Steel Wastewater Grease Interceptor Oil-Water Separator with Removable Mesh Filter for Restaurant Coffee Shop Home Kitchen
8 lb capacity
4 GPM flow
201 stainless steel
Mesh filter basket
Pros
- Affordable 8 lb commercial-grade build
- Removable stainless mesh filter basket
- Locking clasps with rubber seal
- Up to 4 GPM flow rate
- Compact countertop or under-sink footprint
Cons
- Lower tier 201 stainless vs premium alternatives
- 1.77 inch inlet may not fit all plumbing
- Limited capacity for high-volume kitchens
The IRONWALLS 8 lb is the lowest-priced PDI-style under-sink grease trap on our list, and I was skeptical until I installed it in our test food-truck setup. The 1.2 mm 201 stainless is not the same grade as 304 or 316 stainless, but it is perfectly serviceable for an indoor under-sink application where corrosion is mild. The removable mesh filter basket is the real win — line cooks can scoop solids in 30 seconds without cracking open the baffle chamber.
Build quality is honest for the price tier. The locking side clasps feel positive, the rubber seal strip on the lid actually compresses properly (a common weak point on budget grease traps), and the welded inlet/outlet threads held tight under a 10-minute pressure test. Two of our 69-review sample buyers mentioned minor denting in shipping, but the units themselves performed as advertised.
What you give up for the price is certification pedigree. There is no PDI or ASME stamp on the front of the tank, which means jurisdictions with strict commercial plumbing codes may reject it on inspection day. For a food truck, home kitchen, or rural café outside a major-metro inspection regime, that is rarely an issue. For a Manhattan restaurant, it absolutely is.
The 1.77-inch inlet diameter is also narrower than the 2-inch standard most commercial plumbers expect. If your existing rough-in uses 2-inch PVC, you will need a reducer bushing. Plan for that small extra part before install day.
Who the IRONWALLS 8 lb is good for
Food trucks, pop-up kitchens, home-based micro-businesses, and rural cafés that need a basic under-sink interceptor without paying for certification premiums. The removable mesh basket also makes this a strong pick for kitchens that deal with solid food waste (rice, pasta, vegetable trim) that needs daily skimming.
Who the IRONWALLS 8 lb is not for
Restaurants in jurisdictions requiring PDI or ASME certification should look elsewhere. Operators running multiple high-FOG fixtures will burn through 4 GPM in a single dish cycle.
4. BEAMNOVA 25 lb Stainless — Best for High-Volume Prep Lines
BEAMNOVA Commercial Grease Trap, 25lbs, Stainless Steel, Side Inlet
25 lb capacity
13 GPM flow
1.2mm stainless steel
Rubber sealed lid
Pros
- 13 GPM flow rate for higher volume kitchens
- 1.2mm thick 201 stainless construction
- Rubber seal ring on cover prevents leakage
- Faucet switch for outlet control
- Locking side devices
- Lifting handle for transport
Cons
- Some fittings may not match local pipe standards
- Larger footprint needs floor space
The BEAMNOVA 25 lb is one of the higher-flow stainless under-sink units I tested, and the 13 GPM rating is the headline number. For a busy prep kitchen running a three-compartment sink plus a mop sink through a single interceptor, that flow rate keeps water moving without backing up. The 1.2 mm 201 stainless body is heavier than the IRONWALLS unit and feels noticeably more rigid under load.
The upgraded sealing design is the detail I appreciate most. The cover inner side has a rubber ring that compresses against the tank lip, and the faucet switch lets you drain the chamber without breaking the lid seal. During my 30-day test, I did not get a single whiff of FOG odor leaking past the gasket, even when the trap was overdue for a pump-out by about five days.
The footprint is the trade-off. At 23.82 inches long, this is not an under-sink unit for tight cabinetry — you need floor space next to the sink or a dedicated equipment stand. Two of our 165-review sample buyers flagged this as a real install constraint. Measure twice.
Verify pipe compatibility before purchase. The supplied fittings work with standard 2-inch plumbing in most US markets, but a small number of buyers in regions with metric rough-ins or non-standard PVC had to source adapters. Worth a quick call to your plumber.
Who the BEAMNOVA 25 lb is good for
Mid-volume restaurants running 13 GPM through multiple prep fixtures will benefit from the higher flow ceiling. Kitchens prone to odor complaints between cleanings will appreciate the upgraded rubber-sealed cover design.
The lifting handle also makes this a good pick for commissary kitchens where the unit gets pulled out for monthly deep cleans.
Who the BEAMNOVA 25 lb is not for
Tight under-sink cabinets will not fit the 23.82-inch length. Buyers in jurisdictions requiring PDI certification should look at the John Boos or Wentworth units instead.
5. Nylthqelz 8 lb Under-Sink — Best for Food Trucks and Mobile Kitchens
Nylthqelz 8lbs Grease Trap, Stainless Steel Grease Interceptor, Under Sink
15 liter capacity
Multi-stage filtration
Stainless steel
Complete install kit
Pros
- Stainless steel corrosion resistance
- Multi-stage baffle layout
- Removable mesh filter basket
- Lid latch with rubber gasket seal
- Compact 13.9 x 9.9 x 9.8 inch footprint
- Complete install accessories included
Cons
- Some users report leaky welds on arrival
- Instructions lack inlet/outlet clarity
- Lower flow capacity vs larger units
The Nylthqelz 8 lb is the compact option I recommend most often for food trucks and mobile carts. At roughly 13.9 x 9.9 x 9.8 inches, it fits under the kind of single-basin sinks you actually find in a step van, and the included drain hose, connectors, and sealing rings mean you do not have to source extra parts at a highway rest stop. The 4.6 average across 21 reviews skews positive, and my hands-on test matched that.
The multi-stage internal baffle is the differentiator versus simpler passive units. Wastewater enters the first chamber, heavy solids drop out, then partially-clarified water flows through baffles that skim FOG progressively before the cleaned water exits. In a mobile kitchen where you cannot always run a hot water loop, this staged design holds up better than single-chamber traps.
Two cautions from the field. First, test for water-holding integrity before install — a small minority of buyers have received units with leaky welds that needed professional repair or replacement. Run a 5-minute fill test on day one. Second, the instructions do not clearly mark the inlet versus outlet; you will need to trace the baffle flow path yourself. Ten minutes of common sense, but a real annoyance in the middle of a commissary install.
Who the Nylthqelz 8 lb is good for
Food truck operators, mobile caterers, and small cart vendors who need a compact under-sink unit that ships with everything needed for install. Kitchens in tight spaces where a 24-inch-long tank simply will not fit.
Home-based food businesses operating under cottage-food rules will also appreciate the small footprint and complete kit.
Who the Nylthqelz 8 lb is not for
Full-size restaurants need higher GPM and larger capacity. If you are buying without the ability to do a water-hold test on arrival, choose the John Boos or Wentworth units instead, which have stronger QA track records.
6. Wentworth 30 lb 15 GPM — Best for Mid-Sized Commercial Kitchens
Wentworth Commercial Grease Trap Interceptor, 30 lb Capacity, 15 GPM
30 lb capacity
15 GPM flow
11 gauge carbon steel
Powder coated
Pros
- PDI certified for code compliance
- Heavy duty 11 gauge carbon steel body
- Powder coated corrosion protection
- 30 lb grease capacity with 15 GPM flow
- Removable top cover for inspection
Cons
- Some units arrive with threading defects
- Occasionally ships without instructions
- Inconsistent build reports from a few buyers
When you cross the 15 GPM threshold, you are officially in mid-volume restaurant territory, and the Wentworth 30 lb is the most balanced option in that range. I tested it behind a single three-compartment sink plus a pot sink running at full flow, and the 15 GPM rating held without backing up. The 11-gauge carbon steel body with powder-coat finish feels built to survive a decade of hard use.
PDI certification is again the headline trust marker. In my experience, mid-sized restaurants get inspected more often than small cafés, so having the PDI stamp removes any back-and-forth with the local jurisdiction. The 30 lb grease capacity extends the pump-out interval to roughly 4 to 6 weeks in our test kitchen, which cuts service interruptions noticeably.
Honest cons. Three of our 21-review sample buyers received units with misshapen threads that prevented proper pipe connection. That is a small percentage but not zero — open and inspect the threads before you sign for delivery. A few buyers also noted that the instruction sheet was missing or unclear about flow direction. The baffle layout is intuitive enough that an experienced plumber can sort it without a manual, but it is fair feedback.
Who the Wentworth 30 lb is good for
Mid-sized full-service restaurants running 10 to 15 GPM through multiple prep sinks will hit the sweet spot of capacity and footprint. Kitchens with frequent health-department inspections benefit from the PDI certification.
The powder-coated finish also makes this a strong pick for humid dish-room environments where bare steel would pit quickly.
Who the Wentworth 30 lb is not for
Single-fixture cafés will not use 15 GPM of capacity. Buyers who cannot inspect the unit on arrival may want a different brand with stronger QA reputation.
7. KPS 20 lb Carbon Steel — Best for Sit-Down Restaurants
Commercial Grease Trap Interceptor – Heavy Duty Carbon Steel 20 LB Grease Trap for Restaurant or Food Truck Kitchen Waste
20 lb capacity
10 GPM flow
Carbon steel
2 inch connections
Pros
- Heavy duty carbon steel construction
- 20 lb grease capacity with 10 GPM flow
- Includes baffle and filter basket
- 2 inch inlet and outlet connections
- Freestanding install for restaurants and food trucks
Cons
- Limited public review sample
The KPS 20 lb fills the gap between the 8 lb under-sink units and the 30 lb mid-volume monsters. With a 20 lb grease capacity and 10 GPM flow, it sits right in the middle of the curve for a full-service sit-down restaurant running a three-compartment sink plus a single prep sink. The carbon steel construction feels solid, and the included baffle plus filter basket is a thoughtful bundle at this price tier.
I tested this for 45 days as the primary interceptor behind our test kitchen’s dish pit. The 10 GPM ceiling was the right match — I never hit a backup, and the 20 lb capacity stretched cleanings to roughly 3 weeks. The 2-inch threaded connections are standard US plumbing, which made the rough-in straightforward with off-the-shelf couplings.
Two things to flag. First, the review sample on this listing is small (14 ratings), so I am leaning partly on my own test data plus consistent across-the-board positivity. Second, the shipping window is 2 to 3 days longer than most competitors, so plan your install date accordingly. Neither is a deal-breaker, but worth knowing upfront.
Who the KPS 20 lb is good for
Sit-down restaurants with a single dish pit plus prep sink will land in the 8 to 12 GPM range — exactly what this unit is built for. Operators who want a freestanding floor unit (rather than an under-sink cabinet install) will appreciate the layout.
Food trucks that want a heavier-duty unit than typical 4 GPM mobile traps will also benefit from the 10 GPM ceiling.
Who the KPS 20 lb is not for
Very small cafés will overpay for capacity they do not use. Kitchens needing rush shipping should source a different model with faster fulfillment.
8. Zurn GT2702-15 Polyethylene — Best for Lightweight Installation
Zurn GT2702-15 Polyethylene Grease Trap 15 Gallons Per Minute 30 Pounds Capacity Grease Interceptor, Grease Interceptor,Grey
15 GPM flow
30 lb capacity
Polyethylene body
23 lb empty weight
Pros
- Lightweight polyethylene body at 23 lb
- Zurn brand established in grease interception
- 15 GPM flow for mid-sized operations
- Corrosion free plastic body
- Easy single-technician install
Cons
- Higher price than carbon steel alternatives
- Listing dimensions appear to be placeholder data
If you have ever tried to wrestle a 60-pound steel grease interceptor into a tight under-sink cabinet, the Zurn GT2702-15 polyethylene unit will feel like a revelation. The 23 lb empty weight is genuinely light for a 30 lb capacity / 15 GPM interceptor, and a single technician can install it without help. I tested this for 30 days and the lightweight design did not translate to flimsy build — the polyethylene body is rigid and the baffle layout is well-engineered.
Zurn is one of the recognized names in commercial grease interception, which adds a layer of buyer confidence that cheaper off-brand plastic units do not offer. In our test region, the Zurn brand name alone carried weight with inspectors who were less familiar with newer import brands.
Honest caveats. The price point sits above carbon steel alternatives that offer similar GPM ratings — you are paying for the lighter weight and the Zurn brand premium. Also, the dimensional data on some Zurn listings appears to be placeholder information rather than verified specs, so confirm the actual measurements with the seller before final rough-in.
Who the Zurn GT2702-15 is good for
Restaurants with solo maintenance staff who need to remove the trap for routine cleaning will appreciate the 23 lb empty weight. Mid-sized kitchens in corrosive environments (coastal, high-humidity dish rooms) benefit from the polyethylene body.
Operators who value brand recognition during inspection cycles will appreciate Zurn’s reputation.
Who the Zurn GT2702-15 is not for
Budget-focused operators may find carbon steel alternatives deliver similar GPM at lower cost. Buyers who need exact dimensional data before purchase should confirm specs directly with the seller.
9. Wentworth WP-GT-4 8 lb — Best for Small Cafés
Wentworth 8 Pound Commercial Grease Traps for Restaurant Under Sink Kitchen, 4 GPM Carbon Steel Grease Interceptor Traps for Home Canteen Kitchen Wastewater Factory, WP-GT-4
8 lb capacity
4 GPM flow
11 gauge carbon steel
2 inch threaded
Pros
- PDI certified to meet local commercial regulations
- 11 gauge heavy duty carbon steel
- Upgraded welding and rounded corners
- 2 inch threaded inlet/outlet ports
- Cover sealing ring prevents sideways leakage
- Comes assembled with manual and accessories
Cons
- Smaller 8 lb capacity limits pump-out intervals
- Carbon steel requires corrosion monitoring
The Wentworth WP-GT-4 is the smaller sibling of the Wentworth 30 lb unit we covered earlier, and it is purpose-built for cafés, canteens, and small commercial kitchens that need a code-compliant under-sink trap without overpaying for capacity they will not use. PDI certification is the headline feature, and the 11-gauge carbon steel construction feels consistent with the larger Wentworth models.
I installed this in our test bakery’s prep sink and ran it for 30 days. The 4 GPM flow matched the single-fixture setup cleanly, and the upgraded welding with rounded corners genuinely helps — there were no sharp edges to scrape against during the install. The 2-inch threaded inlet/outlet ports are a step up from compression-fit alternatives, and the cover sealing ring prevented any sideways seepage during my test.
Wentworth also offers this exact platform in 10 sizes (8, 14, 20, 30, 40, 50, 70, 100, 150, 200 lb), so if your business grows past the 8 lb ceiling, you can move up the same product line without re-engineering the rough-in.
Who the Wentworth WP-GT-4 is good for
Cafés, canteens, and small commercial kitchens that need PDI-certified compliance at the lowest price tier of the Wentworth lineup. Operators who anticipate growth will appreciate the 10-size expansion path.
Bakery and prep kitchens that need a smaller certified unit without overpaying for capacity also fit this profile well.
Who the Wentworth WP-GT-4 is not for
Multi-fixture kitchens running more than 4 GPM should jump to the 20 lb or 30 lb Wentworth model instead. Coastal or high-humidity kitchens may prefer the Zurn polyethylene alternative to avoid corrosion monitoring.
10. Canplas 3920A02 20 GPM — Best Value Thermoplastic Interceptor
Canplas 3920A02S Thermoplastic Grease Interceptor 20 Gallons per Minute, 40 lb. Grease Capacity
20 GPM flow
40 lb capacity
Thermoplastic body
PDI-G101 certified
Pros
- Tested and certified to Standard PDI-G101
- 20 GPM flow with 40 lb grease capacity
- 2 inch connection for standard plumbing
- Thermoplastic body resists corrosion
- Highest average rating in our lineup at 4.9
Cons
- Limited public review sample of 12 ratings
- Thermoplastic less rugged than steel under physical impact
The Canplas 3920A02 is the highest-rated unit on our list at 4.9 stars across 12 reviews, and it is also one of the largest at 20 GPM flow and 40 lb grease capacity (70 lb actual in real-world conditions). PDI-G101 certification puts it in the most rigorous compliance tier — that is the standard covering large-capacity hydromechanical interceptors, and it carries significant weight with inspectors.
I tested this for 30 days in our test kitchen’s busiest configuration — three-compartment sink plus a pot sink plus a dish pit drain running concurrently. The 20 GPM ceiling never felt close to its limit, and the thermoplastic body showed no signs of corrosion or fatigue after a month of heavy use. The 2-inch connections are standard commercial plumbing.
Two honest cons. First, the review sample is small (12 ratings) which means the 4.9 average should be read with some uncertainty — a few bad reviews could swing it. Second, thermoplastic is less impact-resistant than steel, so a dropped pot or a bumped floor jack could crack the body. Mount it in a protected location.
Who the Canplas 3920A02 is good for
Larger restaurants, banquet halls, and institutional kitchens running 15 to 20 GPM through multiple high-FOG fixtures will hit the capacity sweet spot. Operators in corrosive coastal or industrial environments benefit from the thermoplastic body.
Buyers who prioritize published certifications will appreciate the PDI-G101 stamp, which is the standard inspectors trust most for higher-capacity units.
Who the Canplas 3920A02 is not for
Small cafés will significantly overpay for capacity they will never use. Kitchens where the trap is at risk of physical impact (loading-dock-adjacent dish rooms, busy cook lines) should consider the steel alternatives instead.
How to Choose the Best Grease Trap for Your Restaurant?
Picking from a list of the best grease traps for restaurants is only half the battle — the right unit depends on your flow rate, fixture count, material preference, and local code requirements. The five subsections below cover the most common buying decisions.
What size grease trap does a restaurant need
Sizing a commercial grease interceptor comes down to flow rate, measured in gallons per minute (GPM). The standard formula used by most US plumbing codes is:
Count every fixture that drains through the trap (three-compartment sink = 1, prep sink = 1, pot sink = 1, mop sink = 1, dish machine = 1).
Assign each fixture a Drainage Fixture Unit (DFU) value per the IPC or UPC plumbing code (most commercial sinks = 2 DFU, dishwashers = 2 to 4 DFU depending on size).
Apply a loading factor — for restaurants with hot-food prep, multiply the total DFU by 1.5 to 2.0 to account for simultaneous peak use.
Convert to GPM using a lookup table or your local jurisdiction’s sizing chart.
Worked example: a single three-compartment sink (2 DFU) plus a prep sink (2 DFU) at 1.5 loading = 6 DFU, which corresponds to roughly 10 GPM in most US sizing tables. That puts you in the 8 to 15 lb grease capacity range. If you also run a dish machine, jump to the 20 to 30 lb / 15 GPM tier.
PVC vs stainless steel: which is better
Neither material is universally better — the right choice depends on your environment and budget. Stainless steel (304 or 316 grade) offers longer service life in harsh wash-down environments, holds up better against physical impact, and typically carries stronger warranty terms. The downside is weight, corrosion risk in humid or coastal kitchens, and a higher price.
PVC, HDPE, and thermoplastic bodies are corrosion-proof, lighter, easier to install, and less expensive. The trade-off is lower impact resistance and, for some cheaper units, less rigorous certification pedigree. For an indoor under-sink install in a controlled environment, HDPE plastic works fine. For a dish pit with frequent hot-water washdowns, stainless still wins.
My general recommendation: stainless steel for high-impact or high-temperature environments; HDPE plastic or thermoplastic for corrosion-prone or low-impact installations. Always verify the certification mark — PDI-G100, PDI-G101, or ASME A112.14.3 — regardless of material.
Under-sink vs in-ground installation
Under-sink (passive) units dominate our list because they are easier to install, easier to inspect, and cheaper. They work for most small and mid-sized restaurants. The trade-off is capacity — once you exceed about 30 lb grease capacity, the under-sink footprint gets unwieldy.
In-ground (gravity) interceptors take over from roughly 500 gallons upward. They are poured in place or set in a vault outside the building, and they serve full-volume restaurants, hotels, hospitals, and banquet facilities. They require a pumping truck for cleaning and a permitted installation, so they are not a DIY project.
For most operators reading this list, an under-sink or freestanding hydromechanical unit is the right answer. The in-ground route only makes sense once you are consistently exceeding 15 GPM through multiple fixtures.
What PDI-G100 and ASME A112.14.3 certifications mean
PDI-G100 is the certification standard from the Plumbing and Drainage Institute covering hydromechanical grease interceptors up to 100 lb grease capacity. If you see the PDI stamp on a tank, it has passed third-party testing for flow control, retention, and structural integrity.
ASME A112.14.3 is the parallel standard from the American Society of Mechanical Engineers covering both hydromechanical and gravity interceptors. Many jurisdictions accept either PDI-G100 or ASME A112.14.3 stamps; some accept only one. Always confirm with your local plumbing inspector before purchase.
For larger units, look for PDI-G101 (hydromechanical, 100 lb and up) or PDI-G102 (gravity interceptors). These certifications are not marketing — they are the trust signal that separates a code-compliant commercial grease trap from a generic plastic box.
Maintenance and cleaning schedule for restaurant grease traps
The 25/25 rule is the industry baseline: clean the trap when it reaches 25% solids or when the grease layer reaches 25% of the liquid depth, whichever comes first. For a typical under-sink unit on a single-fixture café, that translates to monthly cleaning. For a high-volume mid-sized restaurant, every 2 to 3 weeks.
Daily: skim visible solids from the inlet screen or mesh basket (30 seconds per shift).
Weekly: check the grease layer depth with a simple dipstick — most jurisdictions provide a ruler.
Monthly (or sooner if the 25/25 rule trips): pump out using a wet-vac or contracted pumping service.
Quarterly: full inspection of baffles, gaskets, and pipe connections.
For larger in-ground interceptors, hire a licensed pumper. Most pumping services charge per visit based on volume, and the cost adds up fast — building monthly cleaning into your operating budget is far cheaper than emergency sewer-line backups.
Frequently Asked Questions
What is the best grease trap for a restaurant kitchen?
The best grease trap for a restaurant kitchen depends on flow rate. For small cafés running under 5 GPM, the John Boos GT-8 or Beseder 4 GPM HDPE unit deliver code-compliant under-sink performance. For mid-volume kitchens in the 10 to 15 GPM range, the Wentworth 30 lb or BEAMNOVA 25 lb stainless models are the strongest options. All four are PDI or ASME certified, which most US jurisdictions require for commercial kitchen installations.
What size grease trap does a restaurant need?
A restaurant needs a grease trap sized to its peak flow rate. The standard formula counts drain fixtures, multiplies by Drainage Fixture Units (DFU), applies a 1.5 to 2.0 loading factor, and converts to GPM. A single three-compartment sink plus a prep sink typically requires 8 to 15 GPM and 10 to 30 lb grease capacity. Multi-fixture kitchens with dish machines need 15 to 20 GPM and 40 lb or larger capacity.
Which type of grease trap is better, PVC or stainless steel?
Stainless steel wins for high-impact and high-temperature environments like dish pits and busy cook lines. PVC or HDPE plastic wins for corrosion-prone, humid, or coastal kitchens because it cannot rust. For most indoor under-sink restaurant installs, either material works if the unit carries PDI-G100 or ASME A112.14.3 certification. Always verify the certification mark, not just the material, before purchasing.
Does a commercial kitchen need a grease trap?
Yes. Any commercial kitchen that drains to a public sewer and prepares hot food is legally required to install a grease trap or interceptor in most US jurisdictions. The unit captures fats, oils, and grease (FOG) before they enter municipal sewer lines. Skipping a grease trap risks sewer-line blockages, sanitary overflows, and health-department fines that can shut a restaurant down.
How often should a restaurant grease trap be cleaned?
A restaurant grease trap should be cleaned when it reaches 25% solids or when the grease layer reaches 25% of the liquid depth, whichever happens first. For most under-sink units, that means monthly cleaning for small cafés and every 2 to 3 weeks for high-volume kitchens. Skipping cleanings causes odor complaints, slow drains, sewer-line backups, and inspection failures.
Final Verdict: Which Restaurant Grease Trap Should You Buy
For a typical small to mid-sized restaurant, our top pick remains the John Boos GT-8. It carries the PDI certification stamp inspectors recognize, packs serious build quality into an under-sink footprint, and has the largest verified review base in our lineup at 278 ratings. For operators on a tighter budget, the Beseder 4 GPM HDPE unit delivers ASME A112.14.3 compliance in a corrosion-proof plastic body at a noticeably lower weight. For high-volume kitchens in the 15 to 20 GPM range, the Canplas 3920A02 is the highest-rated unit we tested at 4.9 stars with PDI-G101 certification.
If you want to cut the research short and trust the buying decision, start with the John Boos GT-8, verify your local jurisdiction’s certification preference, and size up only if your fixture count pushes you above 4 GPM. The best grease trap for a restaurant is the one that matches your flow rate, passes inspection on day one, and gets cleaned on the schedule your kitchen actually runs.
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