Drain Fly and Small Fly Service in a Restaurant

Purpose

Small flies in a kitchen are not an air problem, they are a wet organic film with a street address. Every one of them completes its larval stage inside a medium you can put a hand on: the gel layer on a drain pipe wall, the fermenting film in a soda gun holster, the sludge under a floor sink basket, the soil in a decorative plant, or sewage under a cracked slab.

This standard makes the LOCATION the deliverable. A numbered tape count per wet point tells you which medium is producing, and mechanical removal of that medium is the treatment. A space spray resets the visible count for a shift and teaches the operator the shop's product does not work, because by the next service the same medium has emerged another brood.

Scope

Covers small flies at restaurants, bars, cafes, delis and small retail food service: drain or moth flies, phorid or humpbacked flies, fruit flies, fungus gnats and small dung flies. Covers the wet map from the mop sink to the dumpster pad, and the drain work a technician does with a brush and a foamer.

Does not cover house flies and other large filth flies, which are an exterior harborage and door problem; cockroach in the same kitchen, owned by the German cockroach program; a plant under an external food-safety audit, where documentation follows the audit standard; or any repair inside a drain line, which is a licensed plumbing scope this SOP hands off rather than attempts.

Roles and responsibilities

Procedure

Step 1 - Identify the family before you touch a drain. Catch adults on a card or in a vial and read them under a lens. Fluttery, moth-like and slow reads as a drain fly, which breeds in the gel film on a pipe wall. Fast, erratic, running rather than flying reads as a phorid, which breeds in any decaying wet organic material and is the one species that regularly comes from under a slab. Red-eyed over fruit or a bar gun reads as a fruit fly; a fly rising from a potted plant is a fungus gnat. Acceptance: a family name per complaint area, with the cue that decided it. Wrong looks like "small flies, treated", which cannot direct a single tool. Stop rule: phorids in numbers with no surface medium found at step 4, hold the sub-slab possibility live and take step 8's referral rather than foaming again. Hazard: identify at a table away from the cook line, because a tech head-down over a vial beside a working range is how a burn happens.

Step 2 - Take the area before any tool comes out. Service happens off-hours or between services, with the cook line down and food covered or removed. Acceptance: fryers off and cooled, ranges and flat tops off, dish machine idle, food and food contact surfaces cleared or covered, wet floor signs out at the work area. Wrong looks like drain work beside a running fry station because the operator did not want to lose the shift. Stop rule: the operator will not shut the line, reschedule rather than working around it, and record the refusal. Hazard: frying oil holds enough heat for a full-thickness burn long after the fryer is switched off, so nobody works under, beside or over a fryer that has not cooled, and the dish machine stays idle because its rinse cycle and its drain discharge are both scalding.

Step 3 - Lock out the disposal and any powered wet equipment before a hand goes near it. Any sink you will reach into, and any disposal, gets its energy isolating device locked and tagged under 29 CFR 1910.147, then verified. Acceptance: the disconnect or breaker locked and tagged, the wall switch tried with every hand clear of the opening, and no rotation observed. Wrong looks like flipping the wall switch off and trusting it, which leaves a switch anybody can bump and a hand inside an impeller. Stop rule: no lockable isolating device exists, nobody reaches into that unit at all - brush from above with a long tool only, and route the lock provision to the account as a written finding. Hazard: an impeller does not need speed to remove fingers, so the try-start is the control rather than the intention to be careful, and the lock stays on until step 7 removes it.

Step 4 - Map the wet points and take a numbered tape count at each. List every floor drain, floor sink, mop sink, dish machine drain, bar sink, condensate pan, soda gun holster, beer drip tray, dumpster pad and potted plant, and lay clear tape sticky side down across each drain opening leaving a gap so it still passes water. Read the tape after a full overnight cycle. Acceptance: a count of adults per numbered location rather than a house total, over a route as long as the kitchen actually is. Wrong looks like tape sealing a drain completely, which backs up water, sweats and produces a count nobody can use. Stop rule: a location that cannot be taped gets logged untested rather than zero. Hazard: reaching under equipment means an LED light first and a tool second, never a blind hand into a dark void, because broken glass, a discarded blade and an uninsulated hot line all live in that gap.

Step 5 - Remove the medium mechanically, because that is the treatment. Run a long-handled drain brush the full height of the pipe wall above the water line, where the film actually sits, then scrape the drain lip, the grate underside and the floor sink basket, wash holsters and drip trays, replace mop heads, degrease grout voids and equipment leg bases, and empty and dry condensate pans. Acceptance: the brush comes back clean on a final pass at each drain and a swab of the pipe wall shows no gel. Wrong looks like product poured down a drain with no brushing, which runs straight to the trap and leaves the film untouched. Stop rule: a grate that will not lift or a pipe wall you cannot reach is not declared clean, it is recorded unreached and routed to the account for access. Hazard: brushing lifts a wet aerosol of biofilm, so a face shield plus respiratory protection under a written program per 29 CFR 1910.134 covers the inhalation route and gloves and an apron cover the contact route, and no acidic drain product goes into a drain holding chlorine sanitizer, because that combination releases chlorine gas into the room you are kneeling in.

Step 6 - Apply only what the label permits in a food area. For drains, a microbial or enzyme product applied as a foam is the working choice because foam holds against the vertical pipe wall where a pour does not; it is not a pesticide and it consumes what is left after brushing. Where a pesticide is used, its label must name drains and food areas, and applying it otherwise is use inconsistent with the labeling under FIFRA at 7 U.S.C. 136j(a)(2)(G). Acceptance: product, rate and each treated site recorded, foam visibly filling to the pipe wall rather than running to the trap, and nothing applied over exposed food, prep surfaces or an ice machine. Wrong looks like a space spray over the kitchen, which drops the adult count for one shift and changes nothing about the medium. Stop rule: the label does not name drains or food areas, it does not go in. Hazard: label PPE is a condition of use, and an aerosol in a closed kitchen with the hood off is an inhalation route, so run the hood or ventilate and keep people out for the label's stated interval.

Step 7 - Put it all back and verify what you disturbed still works. Clear tools and rags from every sink, confirm the disposal chamber is empty by sight, then remove the lock and tag under 29 CFR 1910.147(e) after telling the kitchen staff you are restoring power. Acceptance: the disposal runs normally with the splash guard seated, no leak at any drain connection you loosened, grates and baskets seated, and any equipment you moved returned and level with its gas connector and drain line undisturbed. Wrong looks like a restored disposal with a brush still in the chamber, or a floor sink left open under a prep table. Stop rule: a leak or an abnormal noise at restart, shut it down, re-lock it and hand the equipment to the account's plumber rather than adjusting it. Hazard: stand clear of the sink opening at restart with everyone's hands out, because a tool left behind is thrown by the impeller, and squeegee the wet floor before staff walk back in.

Step 8 - Recount at 7 days and read it per location. Fresh tape at the same numbered locations, read after a full overnight cycle. Acceptance: catch at each location down at least 80 percent from that location's own tape baseline, AND a clean brush pass with no gel at the two highest-count locations. Judge per location, not on the house total. Wrong looks like a total that halved while one drain carries almost all of it. Stop rule: a location flat after its medium was cleaned means the source is not that surface, and with phorids over a clean pipe wall that reads as a broken line or sewage under the slab, which routes to a plumbing camera inspection and a written scope change, never a third foaming. Hazard: every re-entry repeats steps 2 and 3, because a kitchen that was cold last visit may be hot this one and the lock came off at step 7.

The record this produces

Per visit: family per complaint area with the identifying cue, the numbered wet map, tape counts by location and date, what was brushed and what came back clean, lockout applied and released, product with rate and sites, restoration confirmed, and every location logged unreached or untested with the reason.

The tape counts beside the cleaning notes settle the argument that ends these accounts. A location cleaned and falling is service working. A location cleaned and flat is a source you have not reached, and the answer is access or a plumber, not more product.

Worked pass: phorid flies at a 60-seat restaurant

Step 1 identifies phorids from running, erratic adults at the dish area. Step 2 gets the line down at close with fryers cold. Step 3 locks the prep sink disposal; the bar disposal has no lockable disconnect, so under step 3's stop rule nobody reaches into it, it is brushed from above only, and the missing lock provision is written up for the account.

Step 4 tapes the six wet points this kitchen has: three floor drains, the mop sink, the dish machine drain and the bar floor sink. Overnight counts read FD1 4, FD2 61, FD3 7, mop sink 9, dish drain 3, bar sink 12, so 4 + 61 + 7 + 9 + 3 + 12 is 96 adults, with FD2 carrying most of it.

Step 5 brushes every drain; FD2's brush returns clean on the third pass and a swab shows no gel, so step 5's acceptance is met there. Step 6 foams the drains with a microbial product. Step 7 restores the prep sink disposal, which runs with the guard seated and no leak.

Step 8 at 7 days: FD1 0, FD2 54, FD3 1, mop sink 1, dish drain 0, bar sink 2, so 0 + 54 + 1 + 1 + 0 + 2 is 58. The house total falls from 96 to 58, which is 38 fewer on a base of 96, or about 40 percent, and read as a total that looks like ordinary progress. Per location it is not. FD1 and the dish drain clear to zero. FD3 7 to 1 is 6 fewer on 7, or 86 percent, passes. Mop sink 9 to 1 is 8 fewer on 9, or 89 percent, passes. Bar sink 12 to 2 is 10 fewer on 12, or 83 percent, passes. FD2 61 to 54 is 7 fewer on 61, or 11 percent, which fails the 80 percent gate.

Step 8's stop rule fires as written: phorids, a pipe wall that brushed clean at step 5, and a flat count. No third foaming happens. The camera inspection finds a broken lateral under the slab near FD2, and the account gets a repair scope instead of a monthly argument about whether the service works.

References

• FIFRA, 7 U.S.C. 136j(a)(2)(G), and the drain, food-area and PPE directions on the label of the product in your hand
• OSHA 29 CFR 1910.147 for lockout and tagout of a disposal or powered wet equipment, including the release-from-lockout requirements at 1910.147(e)
• OSHA 29 CFR 1910.134 for any respirator required while brushing biofilm or by a product label, which is a written program with medical evaluation and fit testing
• See related: German Cockroach Treatment Program; Commercial Food-Handling Facility Audit Requirements; Pesticide Label Verification Before Application