Batch Brew

Batch brew is filter coffee made in bulk: a commercial brewer sprays hot water over a big basket of ground coffee and fills an airpot, thermal carafe or urn, so a café or office can pour a cup in seconds. You’ll also see it called bulk filter coffee or “filter of the day”. It’s the same idea as a home drip coffee maker, scaled up to litres and with far more control. Below is a starting recipe from a specialty roaster, what the settings on a commercial brewer actually do, and the honest answer on how long a batch stays good.

The short version

• Start at 60 g of coffee per litre: 120 g for a 2-litre batch, per Five Senses Coffee.
• Grind coarse, and coarser again as the batch gets bigger.
• Aim for about 4:30 of water dispense and 5:30–6:30 total contact time for a 2-litre batch.
• Keep the dry coffee bed 3–5 cm deep, which both Five Senses and Scott Rao recommend.
• Stir the airpot when the brew finishes, then serve it fresh: within 30 minutes to an hour, depending on who you ask.

How is batch brew different from a home drip machine?

The brewing is the same: water drips through a bed of coffee in a paper filter and into a jug. The differences are size and control.

• Batch size. Fetco’s CBS-2050e series makes 1.5 or 2.0 US gallons (about 5.7 or 7.6 litres) per batch at its factory settings, and the volume can be programmed from 0.25 to 3 gallons. The Marco Jet 6 brews up to 6 litres at a time. A home machine usually makes a litre or two.
• Programmable batches. On the Fetco CBS-2050e, each batch size gets its own brew volume, brew time, pre-wet, bypass and drip delay. Curtis’s G4 ThermoPro lets you set each pulse’s on and off times, bypass percentage and drip delay from a touchscreen.
• Temperature from a tank. Commercial brewers keep a tank of water hot. Fetco’s factory setting is 200°F (about 93°C), adjustable from 180 to 208°F.
• Serving. Batch brew usually goes into an unheated airpot or thermal server, not a glass jug on a hotplate.

If you want a café-style machine for home, look at an SCA-certified home brewer, which is tested to brew within the same temperature range a café would aim for.

How much coffee do you use for batch brew?

Start at 60 g of coffee per litre of water. That’s Five Senses Coffee’s starting recipe, and it sits in the middle of the published ranges:

Source	Coffee per litre	For a 2-litre batch
SCA reference point (Golden Cup)	55 g	110 g
The Ministry of Coffee	55–65 g	110–130 g
Five Senses Coffee (starting recipe)	60 g	120 g
Scott Rao	16:1 to 18:1 water to coffee, about 56–63 g	111–125 g

The SCA’s figure is the 55 g per litre Golden Cup reference; its home brewer standard uses the same standard brew ratio and asks for water at 90–96°C. Seattle Coffee Gear sums up the Golden Cup target as 1.15–1.35% TDS at 18–22% extraction. Five Senses’ advice is simple: if it tastes weak, go up towards 65 g per litre; if it tastes too strong, go down towards 55 g.

For a smaller batch, The Ministry of Coffee brews 100 g of medium-ground coffee with 1.5 litres of water in a Moccamaster, with the water fully through after about 5 minutes.

What grind size is best for batch brew?

Coarser than most people think. Scott Rao goes as far as saying that if your batch-brew grind isn’t in the coarsest 15% of your grinder’s dial, there’s a problem somewhere in your setup. He explains that the “auto drip” mark on old restaurant grinders was set for weak recipes of 30–40 g per litre, ground fine to make up the strength.

There’s no universal setting, because brewers, baskets and grinders all differ. Five Senses’ trick is to dial in by time: pick the grind that gives a total contact time of 5:30 to 6:30, and expect to grind coarser as the batch gets bigger. The Ministry of Coffee agrees: more coffee, slightly coarser grind.

Why does bed depth matter?

Bed depth is how high the dry coffee sits in the basket before brewing. Five Senses and Scott Rao both recommend 3–5 cm:

• Too shallow (under 3 cm): water is more likely to channel, and you end up grinding finer than you’d like.
• Too deep (over 5 cm): you need a grind so coarse that the coffee can’t extract properly in a reasonable time, and the basket can overflow.

That’s why batch size and basket have to match. Rao suggests a wire basket insert to narrow the bed if you want to brew small, one-litre batches in a big café basket.

What do pre-wet, pulse brewing and bypass do?

These are the settings that make a commercial brewer more than a big kettle. Here’s what each maker says they do:

Setting	What it does	Example range or default
Pre-wet (pre-infusion)	Sprays a little water, then pauses so the coffee can wet through before the main brew	Fetco: 0–15% of the batch, default pause 1:00
Pulse brewing	Turns the spray on and off in cycles, which stretches the brew time	Fetco: brew time split into 30-second spray-and-pause cycles
Brew time	How long the brewer takes to dispense the water	Fetco: 2:00–24:00, factory 4:00
Bypass	Adds water outside the filter, diluting the coffee without passing through the grounds	Fetco: 0–40% of the batch
Drip delay	Keeps the basket locked while the last coffee drains	Fetco: default 1:30
Temperature	Sets the water temperature in the tank	Fetco: 180–208°F, factory 200°F

Bunn describes the same ideas: pre-infusion lets the wetting phase finish before extraction starts, pulse brew lets you adjust flavour by extending brew time, and variable bypass controls strength.

For a starting point on a Fetco Extractor, Prima Coffee suggests a 2-litre batch, a 4:30 brew time, six to eight pulses and a 10% pre-wet with about a 1:00–1:10 pause. Prima notes that the smaller Fetco 2030 and 2040 series have no bypass; it’s on the larger 50 and 60 series.

Should you use bypass?

Scott Rao says bypass’s main effect is dilution, like adding water to espresso for an Americano. He sees it as a fix for very large batches where the bed would be deeper than about 5 cm, so the brewer can push some water around the bed rather than grinding too coarse. If your batch fits the basket at 3–5 cm, I’d start with bypass at zero, as Fetco’s factory setting does.

How do you dial in batch brew?

Here’s Five Senses’ starting recipe for a 2-litre batch:

Variable	Starting point
Ratio	60 g per litre (120 g coffee, 2 litres water)
Water temperature	96°C, where adjustable
Dispense time	4:30 for 2 litres, 15 seconds less for every extra litre
Total contact time	5:30 to 6:30
Grind	Whatever gives that contact time

Scott Rao lands in the same place: 6:00 to 6:30 total time, without pushing the programmed brew time past 4:30. Then taste and adjust one thing at a time:

Problem	Likely cause	Try
Weak, watery	Too little coffee	Raise the ratio towards 65 g per litre
Too strong	Too much coffee	Lower the ratio towards 55 g per litre
Bitter, dry, astringent	Over-extracted	Grind coarser
Sour, lacking sweetness	Under-extracted	Grind finer
Slurry reached the top of the filter	Grind too fine, restricting flow	Grind coarser
Slurry barely rose	Grind too coarse for enough contact time	Grind finer
Uneven, inconsistent batches	Brewer or basket not level	Level the brewer so water spreads evenly
Murky, stewed taste	Dirty airpots, baskets or spray head	Clean them every day

Five Senses also suggests weighing what the brewer dispenses with an empty basket, to check you’re getting the volume you programmed, and keeping a log of recipes as each coffee ages.

How long does batch brew stay good in an airpot?

This is where the sources disagree most:

Source	Advice
Scott Rao	Serve within 30 minutes; turn carafes over at least once every half hour
Five Senses Coffee	Use a brew within 1 hour
Bunn	20 minutes in an open decanter, 60 minutes in a closed container, held at 80–85°C
Moccamaster CDT Grand (retailer listing)	The thermal jug maintains coffee quality and taste for up to an hour
UC Davis sensory study (Batali et al.)	Likely 90 minutes or more without notable loss; unheated insulated carafes did best

The study, presented at ASIC in 2021, held three coffees for up to three hours in vacuum, thermal-jacketed and glass-on-hotplate carafes and found the changes “subtler than expected”. Still, with batch brew the practical rule is simple: brew smaller batches more often. Rao suggests batches of no more than 2 litres, filling the carafe completely, and running a rotation of three 2-litre carafes in a busy rush rather than one big urn.

Five Senses adds one more habit: stir the airpot once the brew finishes. The coffee that comes out first is stronger than the coffee that comes out last, so it layers in the pot.

How do you choose a batch brewer?

Five Senses’ main advice is to size the brewer to how much you sell in an hour: too small and you’re brewing constantly, too big and coffee sits too long or you’re forced to brew a dose too small for the basket. It counts four 8 oz cups per litre. A few examples of what’s out there:

• Fetco CBS-2050e series: 1.5 or 2 gallons per batch, with programmable pre-wet, pulse and bypass.
• Curtis G4 ThermoPro: 1.5 gallons, with each pulse, bypass and drip delay programmable.
• Marco Jet 6: a plumbed-in brewer that makes 2 to 6 litres per batch into a portable urn, with selectable brew temperature and pulse brewing.
• Moccamaster CDT Grand: 1.8 litres into a thermal jug in about 6 to 7 minutes, sold for small offices and coffee shops.

Scott Rao also looks at the spray head. He prefers flat metal plates with many small holes, which spread water evenly over the bed, to the umbrella-style plastic heads on many newer machines. Flat plates collect scale, though, so he says to soak them in espresso-machine detergent every night.

A short history of batch brew

• 1957: George R. Bunn founds Bunn-O-Matic, now based in Springfield, Illinois, making flat-bottomed fluted paper filters and pour-over drip brewers, according to Wikipedia.
• 1963: Bunn introduces its first automatic drip brewer, Wikipedia says, nine years before its first home model in 1972.
• 2016–2017: consultant Scott Rao publishes his “Batch Brew Basics” posts, pushing cafés towards smaller batches, a 3–5 cm bed and coarser grinds.
• More recently: specialty cafés such as Coffee Collective in Copenhagen added Fetco batch brew alongside their hand-brewed filter, measuring TDS and extraction on every batch. Coffee Collective found the Fetco gave more body and balance than its Kalita Wave.

General guidance only. Commercial brewers run very hot water and should be installed and serviced as the maker specifies. Keep the basket locked until the drip delay ends.

Batch brew vs other methods

• Automatic drip coffee maker: the home version, smaller and with fewer settings.
• SCA-certified home brewer: a home drip machine tested to the SCA’s standard.
• Chemex Ottomatic: automatic brewing into a Chemex.
• Kalita Wave: hand-brewed flat-bottomed filter, often served alongside batch brew.
• V60: a single cup brewed by hand, for lighter, more aromatic filter.
• Cupping: how cafés taste and choose the coffees they batch brew.

Explore more filter methods in the pour-over chapter.