Bar drainage and waste connection

Takes away everything the bar puts down — drip trays, backflush, ice melt, wash-up, treatment discharge and the floor — reliably enough that nobody has to think about it during service.

Gravity, a water seal and air. Every fixture drains by fall, so a run needs continuous slope from the fixture to the stack; a run that flattens, or that was set level to clear an obstruction the joiner discovered late, holds water and solids and becomes the place that blocks. A trap holds a water seal that keeps sewer gas out of the room, and a trap that dries out — a floor gully that only sees ice melt, a drain used once a week — stops being a seal and becomes a vent. Venting matters for the same reason: a discharge that fills the pipe pulls a vacuum behind it and can siphon a trap dry, which is why the traps that fail are often the ones nobody uses rather than the ones that work hardest. And where a drain serves equipment connected to the potable supply, the connection is normally made with a deliberate physical break so that waste can never be drawn back into the water, which in most jurisdictions is a code requirement rather than a supplier's choice. What a BAR adds to all of this is an unusual loading. Milk proteins and fats from steam-wand purges and jug rinsing, sugar and syrup, coffee grounds and fines, and in some installations a continuous treatment discharge running whether anyone is working or not. That mixture congeals on cool pipe walls in a way a domestic kitchen's waste does not, and it does it out of sight. Slope, pipe sizes, venting, trap type, grease interception and backflow protection are all a licensed plumber's design and are governed by the local authority — this site states none of them, and nothing here should be read as a dimension.

Design drainage at the same time as the water supply and before the joinery is fabricated, because every decision in this category has a drain on the other side of it. Reverse osmosis sends concentrate to drain continuously, a regenerating softener discharges brine on every cycle, drip trays and backflush discharge at every clean, and the ice well discharges all day. Adding a drain after the cabinetry is built is one of the most expensive changes on the whole fit-out.
List every discharge in the bar before anyone sizes anything. Espresso machine drain and drip tray, steam-wand purge, group backflush, ice well and ice machine, wash-up sink, hand basin, boiler tray, treatment discharge, floor. A plumber can only design for what they are told exists, and the ones that get left off the list are always the continuous ones nobody thinks of as fixtures.
Decide plumbed or hand-emptied per fixture, honestly, and decide it against how fast that fixture actually fills. A hand-emptied tray costs nothing to install and costs a recurring task forever; a plumbed one is the exact reverse and commits the equipment position permanently. Neither is right in general and both are right somewhere.
Tell the plumber what a bar actually discharges, because it is not what a domestic kitchen discharges. Milk proteins and fats, sugar and syrup, coffee grounds and fines, all of it warm, congealing on cool pipe walls out of sight. Then put a hot flush of the equipment drain line into the closing routine, so the design assumption and the operating routine agree with each other.
Protect the potable supply, and treat that as a professional's decision rather than a supplier's default. Any equipment drain downstream of a treated water supply raises a backflow question, and the physical break that answers it belongs to a licensed plumber and the local authority. This is life-safety adjacent and it is not a detail to be resolved on site by whoever arrives first.
Keep every trap wet, and name the ones that will not stay wet on their own. A floor gully that only receives ice melt in summer dries through a quiet winter and becomes a smell that nobody can locate, and the fix is a jug of water in the closing checklist rather than an investigation.
Put the drain where the mess is, not where the plumbing was convenient. The knock box, the ice well, the wash-up and the espresso lane generate almost all of it, and a drain sited for the builder's ease guarantees that liquid is carried across the bar by hand for the life of the venue — which is also how floors get wet.
Make cleaning access physically possible before you sign off the design. A removable grate somebody can actually lift, a rodding point that is not behind a fixed cabinet, and a run that can be flushed without dismantling anything. A drain that cannot be reached is a drain that is cleaned only after it has already blocked, during service.
Confirm every dimension and requirement with a licensed plumber and let the local authority govern: falls, pipe sizes, venting, trap type, interception and backflow protection. This site deliberately states none of them, and any figure that appears in a supplier's drawing is a proposal to be checked rather than a specification to be trusted.

Underneath everything, and drawn on the same plan as the water supply rather than on a later one. In reading order this entry closes the category because it is the destination of every stage before it — the concentrate stream from the membrane, the brine from the regenerating softener, the water released at every cartridge change, the drip trays and the backflush. On the bar itself the drainage points belong where the liquid is actually generated: the knock box, the ice well, the wash-up and the espresso lane. Anywhere else and the bar spends its working life carrying full trays across a wet floor.

Designing the water supply carefully and leaving drainage until the joinery is already built, when every treatment decision above has a discharge attached to it.
Letting a plumber assume domestic-kitchen loading, when a bar sends milk fats, sugar, syrup and coffee fines down warm and lets them set on cool pipe walls.
Allowing a rarely used trap to dry out and then hunting the resulting smell everywhere except the drain that is no longer sealed.
Treating backflow protection as the equipment supplier's problem rather than a licensed plumber's design governed by the local authority.
Siting the drain where the plumbing was easy instead of where the knock box, the ice well and the wash-up actually are.
Hand-emptying a tray that fills faster than the rota does, and finding out during the busiest hour rather than during the design review.
Fitting an interceptor and leaving it out of the maintenance schedule, which concentrates in one unmanaged place exactly what it was installed to keep out of the pipe.

Continuous fall from every fixture to the stack, a maintained water seal on every trap, and venting adequate to stop a discharge siphoning a seal dry. Falls, pipe sizes, trap type, venting arrangement and whether grease or solids interception is required are a licensed plumber's design, and the local authority governs. This site states no dimensions.
Every equipment drain downstream of a potable supply raises a backflow question, and the physical break that answers it is specified by a licensed plumber and governed by the local authority. It is never resolved by an equipment supplier's default fitting or by whoever is on site on installation day.
Under-counter volume for the runs and traps that the joinery has to be told about before it is built, plus floor space for any interceptor and the access to service it. A waste run designed after the cabinets exist ends up boxed into somewhere it cannot be rodded.
Enough room to lift a grate, reach a rodding point and flush a line without dismantling equipment. Access is what decides whether a drain is maintained on a schedule or only ever attended to as an emergency.
A warm bar accelerates everything a drain smells of, and in a hot climate a neglected run announces itself far faster than the design assumed. Heat is also why a dried trap becomes noticeable within days rather than weeks.

Direct-plumbed equipment waste
Drip trays and machine drains piped straight into the waste run instead of collecting in a tray.
Nobody empties anything, which removes the most-forgotten recurring task on a bar and the one that fails first under pressure. In exchange it fixes the equipment position permanently and it puts milk, sugar and coffee fines into a pipe that now needs a flushing routine of its own — a task moved rather than removed.
Trayed and hand-emptied
A tray under the fixture with no connection to anything, emptied as a named task.
Total flexibility and no installation cost, so the layout can still change and the landlord's fit-out survives. The cost is a recurring task that is only free while it appears in the opening and closing checklists; the moment it lives in somebody's head it becomes the tray that overflows onto a counter during the busiest hour, which is how a bar acquires a hygiene finding.
Floor gully or channel drain
A drain set into the bar floor, with the floor laid to fall toward it.
It makes washing down possible and it catches spills, ice dumps and the water that ends up on the floor of every bar regardless of intention. It needs a maintained water seal and, where it is used rarely, deliberate filling. Decisively, it is a build decision made before the floor is laid — adding one afterwards means taking the floor up, which is why bars that need one and do not have one simply never get one.
Grease and solids interception
A device that separates fats and solids from the flow before it reaches the waste run.
Whether one is required at all is a matter for the plumber and the local authority and depends on what the site discharges, so it is not a choice made from a catalogue. Where one is fitted it becomes a scheduled service item with an owner, a record and a disposal route — and a neglected interceptor is genuinely worse than none, because it concentrates in one place exactly what it was installed to keep out of the pipe.

A sour or drain-like smell at the bar that builds through the day and is strongest near the espresso lane.
Milk fats and solids coating the inside of a waste run that has never been flushed hot, or a trap that has dried and stopped sealing.
A customer-facing quality problem before it is anything else, and a hygiene finding waiting to be written — and it is expensive to chase because the smell arrives nowhere near where the deposit is.
The drip tray backs up during a rush, and always at the busiest group first.
A partial blockage building in a run with insufficient fall or no flushing routine, exposed by the one moment of the day when discharge is continuous.
Downtime taken in the worst possible currency — it is cleared during service, by the person who cannot leave the bar, while the queue watches.
Water standing on the bar floor after a wash-down, or a persistent wet patch that never quite dries.
Floor fall to the gully wrong or absent, or no floor drain at all in a bar that is washed down as though it had one.
A slip risk carried by every shift, an injury that ends one of them, and a floor that has to be lifted to fix properly — the most expensive way to discover a fall was never designed.
A continuous treatment discharge that nobody has looked at since installation day.
It runs whether the bar is open or not and it belongs to no station, so it appears on nobody's checklist and is invisible until something around it is wet.
Money if it has been discharging into somewhere it should not, downtime if it has blocked, and in the worst case a water-supply question if the physical break was never made correctly.

Bar drainage and waste connection

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