Cold brew on tap is one of the highest-margin programs in a specialty café. Done right, it's reliable, scalable, and visually compelling for the bar. Done wrong, it's a sour, stale, oxidised liability. The difference is execution, not equipment.

The economics, briefly

A typical cold brew on tap recipe uses 1 kg of coffee per 8-10 litres of finished concentrate. At a 1:8 dilution to served beverage, that's 64-80 litres of beverage from 1 kg of coffee — or roughly 250-320 12-ounce servings.

If your house cold brew sells at $5.50 and your coffee cost is $20/kg, the gross margin on a single 12oz serving is roughly $5.40 — about 98% on the variable cost side. Even with milk for nitro lattes, cold brew is one of the highest-margin items on a specialty bar.

The constraint is volume — cold brew is only as profitable as the customers drinking it. In high-volume summer months, this becomes the most profitable single line on your menu. In winter, sales drop materially and the inventory carrying cost (kegs sitting in the walk-in) eats into the math.

The equipment options

Three approaches, in increasing order of complexity:

1. Batch in a vessel, store in kegs, dispense via tap. The simplest setup. You brew in a 20-30L food-grade vessel, transfer to 5L or 10L kegs, store cold, dispense via standard beverage tap. Equipment cost: $800-$2,500 depending on whether you reuse existing refrigeration.

2. Toddy commercial system + keg storage. Toddy makes commercial-grade brewing systems specifically designed for café production. The brewing process is the same but the filtration is cleaner and the workflow is faster. Equipment cost: $2,500-$4,500.

3. Nitro tap system with infusion. Adds nitrogen infusion to the dispense for the visual cascade effect customers associate with nitro cold brew. Equipment includes a nitrogen tank, regulator, stout faucet, and either a forced-nitro keg or a continuous infusion line. Equipment cost: $1,500-$3,500 above a basic system.

Most specialty cafés start with option 1 and add nitro infusion if customer demand justifies it. Option 3 is more dramatic visually but operationally more complex.

The recipe — what actually works

Cold brew recipes vary widely, but the ones that produce consistent specialty-quality results converge on a narrow band:

Ratio: 1:8 coffee to water by weight for concentrate. (1 kg coffee, 8 kg water.)
Grind: coarse, similar to French press. Too fine and the brew becomes muddy and over-extracts; too coarse and you under-extract.
Brew time: 16-20 hours at room temperature, then refrigerate. Some operators prefer 14-16 hours cold-brewed in refrigeration the whole time — slightly cleaner cup, slightly less extraction.
Filtration: two-stage. First through a coarse filter (cloth, paper-lined cone), then through a fine paper filter (V60 paper or similar) to remove sediment.
Dilution at service: 1:1 concentrate to water for a balanced 12oz serving, or 1:1 to milk for an iced latte.
Shelf life: 7 days in keg after brewing, refrigerated. Discard at 7 days even if the keg isn't empty.

Coffee selection

Not every coffee makes great cold brew. The pattern: medium-roast, well-bodied, with structural sweetness. Coffees that work well as espresso don't always work as cold brew — the brewing variables are different enough that the cup profile changes.

What tends to work:

Brazilian naturals (chocolate-forward, low acidity)
Honey-process Central Americans (caramel sweetness, body)
Indonesian (Sumatra, Java) for heavier-bodied cups
Ethiopian washed when you want fruit-forward acidity (works but polarises customers)

What tends to disappoint:

Light-roasted Kenyans — the acidity often becomes harsh in cold brew
Anaerobic-process coffees — the funky fermentation notes amplify in cold brew, often unpleasantly
Very-light-roasted Ethiopians — can come across as thin and grassy

Cup-test before committing. A 200g test brew with each candidate coffee, served the next day, tells you what will work in production.

The operational discipline

The single most common cold-brew failure mode is inconsistency. The brew gets made differently each week because different staff make it. The fix is the same as any specialty discipline: write the recipe down, post it next to the brewing equipment, and audit.

The weekly checklist:

Brew schedule: enough capacity to never run out mid-week, but not so much that batches age past 7 days.
Coffee weight checked on a scale every time, not estimated.
Water temperature recorded — room temp is fine, but consistency matters.
Brew start time recorded; finish time set as 18 hours later (or whatever your spec is).
Sensory check before kegging — taste 50ml of the finished concentrate. If it's off, dump it.
Keg labeled with brew date and SKU.

Menu and pricing

Two or three cold brew SKUs is the sweet spot:

House cold brew (your default recipe, served black or with milk on request) — $5.00-$6.00 for 12oz.
Nitro cold brew (same coffee, nitrogen-infused) — $0.50-$1.00 premium over house.
Iced latte using cold brew base — typically same price as an iced espresso latte.
Seasonal feature (single-origin cold brew, rotating monthly) — $1.50-$2.00 premium over house.

The seasonal feature is the menu component that justifies premium pricing. Customers will pay more for "this month's Ethiopian Yirgacheffe cold brew" than for "house cold brew" — same coffee, different story.

What goes wrong

Brewing too far ahead. Cold brew tastes best 24-48 hours after filtration. Stored properly, it holds for a week, but the difference between day 2 and day 7 is real. Brew to demand, not to schedule.
Inadequate filtration. Sediment in the keg muddies the cup, blocks dispense lines, and reads as poor quality even when the coffee was good.
Over-extraction. Too fine a grind or too long a brew creates a harsh, dry, astringent cup. Adjust toward coarser grind and shorter time if you're getting this.
Inconsistent dilution at service. If your bartenders pour different concentrate-to-water ratios shift to shift, customers experience your cold brew as inconsistent. Pre-batch the dilution if possible (some cafés keg the pre-diluted serving strength rather than concentrate), or train rigorously to a single ratio.

Seasonality

Cold brew sales drop 60-80% in winter months in temperate climates. Plan inventory and brewing accordingly. The mistake operators make is maintaining summer brew schedules into October, then writing off aged kegs.

The seasonal adjustment: switch to brewing every 4-5 days in October-March (smaller batches, same recipe), and double up in May-September.

For more

For related operational topics, see menu pricing and inventory management.