Last updated: July 16, 2026 · By Riddhi, Founder at DynoRoute
Key takeaways
- The governing ordinance sets cleaning frequency: the 90-day/25% pair is the default, but 30-day indoor mandates and city-by-city rules override it.
- Baseline by trap type: indoor traps (50–150 gallons) start monthly, and 1,000-gallon-class gravity interceptors start at 6–12 weeks.
- Throughput beats size. The interceptor that runs quarterly behind one kitchen can need monthly service behind a busier one.
- Correct every inherited interval from measured buildup; self-reported schedules usually err toward too-frequent service.
- The interval is the revenue engine of the contract: a 6-week schedule earns roughly double a 12-week schedule on the same account.
- Keep pump logs, manifests, and the reasoning behind each interval on file, because inspectors treat missing records as a separate violation.
Grease trap cleaning frequency is set by whichever FOG ordinance governs the trap's address, not by any single national rule. The default in most places is the 90-day/25% pair: pump at least every 90 days, or once grease and solids reach a quarter of the trap's liquid depth, whichever comes first. That one rule hides the real spread. Some districts mandate 30-day service for indoor traps regardless of buildup, California writes its rules city by city, and a wrong interval either wastes truck time or hands your customer a violation with an inspection trail leading back to your schedule.
If you run a pumping company, you've probably inherited the harder version: sixty accounts across three jurisdictions, intervals copied from whatever the previous hauler did, and a restaurant manager asking why the identical kitchen two doors down gets pumped half as often. If you can't explain how an interval was set, you can't defend it to either of them.
I build route planning software for vacuum-truck fleets, and I've spent this year interviewing the operators who run them. This article covers the interval decision itself; turning intervals into truck-days is the routing side, covered in the interval section of our route planning guide.
What Sets Grease Trap Cleaning Frequency
Three things set a trap's cleaning frequency: the local ordinance's floor, the trap type's physical baseline, and the kitchen's actual output. Nearly everything published answers it for a single restaurant owner; a pumping company answers it across an account book, where the three factors combine differently at every stop.
The ordinance is a floor you can't negotiate. Most FOG programs (fats, oils, and grease) adopt some version of the 90-day/25% pair, but the details are local: Florida sets a statewide benchmark, California leaves intervals to each city, and many districts add flat mandates for specific trap types. Quoting an interval without reading the ordinance is how accounts end up non-compliant on a schedule they paid you to keep.
Trap type sets the starting interval. A 75-gallon indoor trap and a 1,000-gallon buried interceptor fill on completely different clocks, so the account book needs baselines per type before any fine-tuning.
Throughput decides where an account actually lands. Two kitchens with identical tanks fill them at very different rates; measured buildup tells you whether the starting interval is right.
Key Aspects to Consider When Setting Grease Trap Cleaning Frequency
Setting intervals across an account book comes down to five moves: read the ordinance, baseline by trap type, correct from measured buildup, price the interval into the contract, and document why each schedule is what it is.
Reading the Local Ordinance First
Before quoting any interval, pull the FOG ordinance for every jurisdiction you serve and note two things: the maximum interval and any flat mandates by trap type. Here is how the same question answers differently across Florida's statewide benchmark, the 30-day indoor-trap mandates many cities impose, and California's city-by-city rules:
| Jurisdiction | Frequency rule | What non-compliance costs |
|---|---|---|
| Florida (statewide) | Every 90 days or at 25% of liquid depth, whichever comes first | Counties layer permits and fines on top |
| Miami-Dade County, FL | The same 90-day/25% pair, enforced at county level | County FOG program citations |
| Indoor-trap mandate districts (many cities) | Every 30 days regardless of the 25% level | Flat missed-mandate citations |
| San Diego, CA | Set by city ordinance | Up to $2,500 per day per violation |
| Sacramento, CA | Set by regional sanitation ordinance | Up to $5,000 per violation per day |
| San Jose, CA | Set by city ordinance | Up to $2,500 per day, capped at $100,000 per matter |
| Fresno, CA | Set by city ordinance | $100 first, $200 second, $500 each additional within 12 months |
Those caps trace to each city's code (San Diego Municipal Code §64.0301(f), San Jose Chapter 1.14, Fresno §1-404), worth quoting when a customer pushes back. One California line targets the hauler directly: under Penal Code §374.5, illegally dumping material removed from a grease trap is a misdemeanor carrying up to six months in jail and a $10,000 fine, and repeat convictions can bar a hauler from the business for up to five years.
Setting Baselines by Trap Type
Set each new account's starting interval from its trap type, then let measured buildup move it. The two categories behave differently enough that one default interval guarantees you're wrong somewhere:
| Trap type | Typical size | Baseline interval | What moves it |
|---|---|---|---|
| Indoor hydromechanical trap | 50–150 gallons | Monthly; every 30 days where mandated | Fryer-heavy menus push toward weekly |
| Gravity grease interceptor | 500–1,250+ gallons, sized by drainage fixture units under UPC §1014.3.6 (8 DFUs → 500 gal, 35 → 1,000, 90 → 1,250) | 6–12 weeks for most operators, with the 90-day rule as backstop | High-volume kitchens can force monthly |
The caveat that matters: throughput beats size. A 1,000-gallon interceptor typically serves a 150-to-300-seat full-service restaurant on a 6-to-12-week cycle, but high-volume kitchens often need monthly service on the same tank. DFU sizing tells you what the trap was designed to handle; the menu tells you what it actually receives.
Correcting Intervals From Measured Buildup
A baseline is still a guess until the truck reports actual volumes against it. The grease-collection operator I interviewed runs correction as a standing rule: when a stop that should produce a thousand pounds comes back with five hundred a few visits running, that account's four-week frequency moves to six and the schedule resets. The evidence is already on the truck; the discipline is feeding it back into the interval.
Expect corrections to run mostly one direction. An operations lead at a national grease-trap and used-oil collection company told me his intervals skew short across the book, because customers overstate their volume when pricing gets set. Every schedule you inherit from a customer's self-report probably errs toward too-frequent service, which quietly burns route time on half-full traps.
It cuts both ways, though: an account trending toward the 25% threshold faster than its interval allows needs a shorter cycle before an inspector finds the breach, and that conversation goes better with measured numbers than a hunch.
Pricing the Interval Into the Contract
The interval is a pricing decision as much as a compliance one, so write it into the contract explicitly: the frequency, the per-visit price, and a review clause tied to measured buildup. An account's annual value is visits per year times price per visit, which means the frequency term set at signing matters more than most per-visit price negotiations.
Two guardrails keep the pricing honest. Where the ordinance mandates a frequency, quote it as the compliance floor it is, so the customer hears the city's requirement rather than an upsell. And resist shortening intervals just to lift revenue: the same grease-collection operator is blunt that pumping two weeks early is generally unprofitable, because a full route cost goes out to collect a half-full trap. The interval that maximizes an account's value is the shortest one the buildup actually justifies.
Documenting Intervals for Inspectors and Customers
For every account, keep three artifacts: the pump log with measured volumes per visit, the manifests, and a note on why the interval sits where it does. California's city programs expect pump logs, manifests, and disposal certificates kept at least three years, produced on demand, and most treat failure to produce them as a separate violation even when the trap itself is clean.
The same file wins customer conversations. An interval change, in either direction, lands better as a page of expected-versus-actual volumes than as an assertion. The file also has to reflect reality: the operations lead I mentioned found his overdue list included accounts that "may be lost customers," because nothing in his records distinguished a late account from a dead one.
The Numbers Behind Grease Trap Cleaning Intervals
The interval is the single biggest revenue lever in a service contract, and the math is worth running for every account.
Take one account billed at a round $200 per visit, an illustrative figure to keep the arithmetic visible. A 12-week interval means 52 ÷ 12 = 4.3 visits a year, about $870. A 6-week interval means 8.7 visits, about $1,730. Nothing about the account changed except the interval, and its value doubled — provided the buildup justifies the shorter cycle and the customer signs off, which is what the measured-buildup file is for. Multiply that across sixty accounts and interval-setting quietly outweighs almost every other pricing decision you make in a year.
The lever swings both ways, which is why the correction discipline above matters. Every visit carries route cost whether the trap needed it or not; the grease-collection operator I interviewed budgets roughly $95 of overhead per stop in his operation, so a too-short interval pays full freight to collect half a trap. A too-long interval costs differently: the customer eats the violation at the fine scales in the table above, and the account usually leaves with the citation in hand.
The defensible middle is measured: intervals set from recorded buildup converge on schedules where nearly every visit collects a full trap and no account crosses its threshold between services.
Choosing Software to Run Service Intervals Across an Account Book
A dozen accounts on two intervals fit in a spreadsheet. Sixty accounts on five intervals across three jurisdictions stop fitting, usually when interval corrections start landing weekly, and the question becomes whether a scheduling or route optimization tool can hold the interval logic rather than just the map. Evaluate against the book you actually run:
- Recurring cadences per account — weekly, biweekly, monthly, and custom intervals built once and planned automatically
- Volume history per stop — gallons recorded at the stop, so corrections come from data instead of memory
- Interval changes without a rebuild — move one account from four weeks to six and the schedule re-plans around it
- Capacity-aware planning — a shortened interval adds gallons to a route day, and the plan has to respect the tank
- Proof of service — timestamped, geotagged photos attached to every stop
- Published pricing — the cost of running your book knowable before a sales call
DynoRoute holds interval books for capacity-routed fleets: you set what each truck holds and how often each customer gets serviced, and it builds the recurring routes around both; gallons and photo proof are captured per stop in the driver app, and service records flow to QuickBooks for invoicing. Per-truck pricing is public in the pricing guide, and the honest test is to load your own account book and see whether the schedules it builds match the intervals you'd defend.
Frequently Asked Questions
(Google's People Also Ask panel could not be captured for this query at research time; questions below are drawn from search data for the topic.)
Is there a law on how often a grease trap must be cleaned?
There is no single national law. Frequency is set by local FOG ordinances, which typically adopt the 90-day/25% standard, and details vary widely: Florida sets a statewide benchmark, while California leaves intervals to each city. The binding rule for any account is its jurisdiction's ordinance, which is why multi-city operators keep a rules sheet per city.
What is the 90-day rule for grease traps?
The 90-day rule is the calendar half of the standard FOG requirement: a trap must be pumped at least once every 90 days, or sooner if grease and solids reach 25% of its liquid depth, whichever comes first. The 90 days is a backstop, not a schedule; busy kitchens hit the buildup threshold well before the calendar does, and some jurisdictions mandate 30-day service for indoor traps outright.
Can grease trap cleaning frequency change seasonally?
Yes, and operators plan for it. Kitchens produce more grease through holiday stretches and event seasons; the operations lead at a national grease-trap and used-oil collection company I interviewed flagged seasonality as a real driver of collection volume. The practical move is shortening intervals ahead of known surges rather than fielding overflow calls after, the same way you'd make seasonal adjustments on any waste route.
Who sets the cleaning schedule, the restaurant or the hauler?
The ordinance sets the floor, and the restaurant is the party legally responsible for meeting it. In practice the hauler proposes the schedule, because the hauler holds the measured buildup data that justifies one interval over another. The strongest arrangement puts the interval in the service contract with a review clause, so schedule changes come from recorded volumes both parties can see.