Grease Traps, Drains and Plumbing

Nothing stops service more completely than a backed-up drain, and nothing is more predictable or more preventable.

The grease interceptor

What it does. Separates fats, oils and grease from wastewater before it reaches the sewer, where it would solidify and block the public system.

It is a regulated device in nearly every jurisdiction. Sizing, installation, servicing frequency and record-keeping are typically specified by the local authority or water utility.

Two types. Small under-sink interceptors, and larger in-ground or exterior units.

Servicing means pumping out and cleaning, by a licensed waste contractor, with a manifest documenting where the waste went. That manifest is the compliance record.

Frequency

Set by regulation, by volume, or by the quarter-full rule — many jurisdictions require service when accumulated grease and solids reach a quarter of the operating depth.

Under-servicing is the common failure. It produces overflow, blockages downstream, odour, and citations. Some authorities levy substantial penalties for grease discharge.

Over-servicing wastes money and is much less common.

Track it as a scheduled compliance task with the manifests filed against the site. When an inspector asks, the answer is a folder, not a phone call to the contractor.

Drain problems

Kitchen drains block from grease, food solids and, frequently, from things that should not be there.

Floor drains block and produce standing water, which is a slip hazard, a pest attractant and an inspection finding.

Grease lines solidify. A line running through an unheated area is particularly prone.

Roots and structural problems in older buildings.

Preventive drain maintenance — periodic jetting or enzyme treatment — is cheaper than emergency clearance during service. Emergency drain work is among the most expensive call-outs in the trade because it is always urgent.

Preventing blockages operationally

Most of this is behaviour rather than equipment.

Scrape plates before washing. The single most effective measure.

Strainers in every sink, in place and emptied. They get removed because they are inconvenient and that is when blockages start.

No oil down the drain, ever. Waste oil goes to the rendering contractor. This gets violated when a fryer is being drained in a hurry.

Train staff on what causes the closure. A kitchen team that has experienced a drain backup during service does not need convincing; one that has not needs telling.

Mop water disposal into a designated sink, not a floor drain, where the local rules require it.

Other plumbing

Water heaters. Scale, element failure, thermostat drift. A restaurant with insufficient hot water cannot sanitise, which makes this a food safety item rather than a comfort one.

Backflow prevention devices. Required, and requiring annual testing by a certified tester in most jurisdictions. The certificate is a compliance record and it is commonly forgotten until an authority asks.

Water pressure and supply. Affects warewashing, ice production and combi ovens simultaneously. Several appliances underperforming at once points here.

Restroom fixtures, which are guest-visible and generate complaints out of proportion to their cost.

Leaks. Persistent small leaks damage structure, attract pests and appear on water bills long before anyone notices the source.

Preventive tasks

As scheduled by regulation: grease interceptor pumping, with manifests retained.

Quarterly: drain line jetting or treatment on kitchen lines, floor drain cleaning, water heater inspection.

Annual: backflow device testing and certification, water heater flush and anode check where applicable.

Daily, by staff: strainer emptying, drain covers clear, spill clean-up, no oil to drain.

Why this section matters more than it looks

Drain and grease failures share three properties that make them disproportionately damaging.

They stop service immediately. There is no partial operation with a flooded kitchen.

They carry regulatory consequence. Grease discharge and standing water are both citable, and repeat findings escalate.

They are almost entirely preventable by scheduled work and staff behaviour.

An operator with a limited preventive budget should fund refrigeration first and grease and drains second, ahead of most equipment.

The manifest file

Grease interceptor servicing generates a document that authorities ask for, and it is the one operators most often cannot produce.

Every service produces a manifest showing date, volume removed, and the licensed disposal destination.

File it by site, chronologically, with the date in the filename.

Check the frequency against the requirement. Many jurisdictions specify service when accumulation reaches a quarter of operating depth, which for a busy kitchen can mean monthly rather than the quarterly interval on the contract.

Ask the contractor to record the accumulation level at each visit, not just the fact of service. That record justifies the interval you are using and identifies when it needs shortening.

Retain for the period required locally, which is commonly three years and sometimes longer.

An authority asking for manifests and receiving them immediately is an authority that moves on. The alternative is an investigation into the whole grease programme.