# Coffee Urn

Source: https://dailyextraction.com/methods/urn-brewer/
Last updated: 2026-10-20

> Fill the urn with cold water to the cup mark, seat the stem in the heat well, add coarse percolator-grind coffee to the wetted basket and lock the lid. Hamilton Beach suggests 225 g (2¼ measuring cups) for 45 five-ounce cups and about a minute per cup to brew. The ready light means it’s done.

## At a glance

- Ratio: About 1:28–1:31 at full capacity (Hamilton Beach charts)
- Grind: Coarse (sea salt)
- Category: Machines, Pods & Commercial (Percolation)
- Difficulty: Beginner
- Origin: Global & Modern
- Also known as: coffee urn, electric coffee urn, percolator urn, commercial coffee urn, catering urn, large coffee percolator, twin urn

## Steps

1. **Wash it first**: Before the first brew, wash the inside of the urn, the basket and the stem in warm, soapy water. Never put the base, cord or plug in water.
2. **Fill with cold water**: Take out the lid, basket and stem, then fill with fresh cold water to the mark for the number of cups you want. Stay between the urn’s minimum and maximum lines.
3. **Seat the stem**: Push the bottom of the stem (also called the pump tube) firmly into the heat well in the centre. If it isn’t seated, the urn may not percolate.
4. **Wet the basket and add coffee**: Wet the basket so fine particles don’t sift through, slide it onto the stem and add coarse percolator-grind coffee. Keep grounds out of the stem.
5. **Lock the lid**: Lower the lid and turn it until the locking tabs engage in the handles. Never brew with the lid loose.
6. **Plug in and wait**: Plug in. Hamilton Beach says to allow about one minute per cup, so a full 45-cup urn takes roughly 45 minutes.
7. **Serve from the tap**: When the ready light comes on, the urn switches to keep-warm. Lift out the basket and stem if the coffee will sit for a long time, and serve from the tap, never by tipping.

A **coffee urn** is a big electric coffee maker that brews and holds 30 to 100 or more cups at once, then serves them from a tap. Most are **percolator urns**: a tall metal tank with a **stem** up the middle and a **perforated basket** of coffee at the top, the same idea as a [stovetop percolator](https://dailyextraction.com/methods/stovetop-percolator/) scaled up for church halls, offices, canteens, weddings and community events. You'll also hear them called catering urns, commercial urns or percolator urns. Below is how much coffee to use for each cup count, how long it takes, how to keep it hot, and how to clean one, all taken from the makers' own manuals.

## The short version

- **A cup is small:** urn makers count a cup as **5 oz (about 150 ml)**, so a 100-cup urn holds about 14.8 litres.
- **Coffee per batch:** Hamilton Beach suggests **225 g (2¼ measuring cups) for 45 cups** and **478–515 g for 100 cups**.
- **Coarse, percolator-grind coffee.** Fine coffee can flood the basket and leave grounds in the urn.
- **Allow about a minute per cup**, so start a full 45-cup urn around 45 minutes before people arrive.
- **Respect the minimum line:** most urns have a minimum batch of 10 to 20 cups.
- **Lift the basket out** if the coffee will sit on keep-warm for a long time.



## How does a coffee urn work?

A percolator urn uses the same cycle as any percolator. Water heats in a small **heat well** at the bottom, bubbles push it up the stem, and it spreads over the coffee in the basket and drips back down through the grounds. That repeats until the urn decides the coffee is done and stops automatically. Then it switches itself to a lower **keep-warm** heat and a ready light comes on.

![Diagram of a percolator: heat at the base pushes water up a central tube onto a spreader, it drips through coffee in a perforated basket back into the pot](https://dailyextraction.com/diagrams/percolator-cycle.svg "A percolator urn runs this cycle, just with a much bigger tank and a tap at the bottom.")

In some urns the **lid is the spreader**. The stainless steel urn manual for models 407CCU30 to 407CCU100 notes that no separate spreader plate is needed, since the cover does that job. Makers also insist the lid is locked on before you plug in.

Because the brew goes round and round, coffee historian William Ukers argued in 1922 that a pumping percolator isn't "true percolation" at all, but something "midway between decoction and infusion". It's a fair description: the weak brew keeps being heated and sent back over the coffee until it reaches strength.

## How is a coffee urn different from an electric percolator?

The cycle is the same as an [electric percolator](https://dailyextraction.com/methods/electric-percolator/). What changes is the scale and how it's served:

| | Electric percolator | Coffee urn |
| --- | --- | --- |
| Typical size | A few cups, like Presto's 6-cup | About 30 to 100 cups, or more on commercial models |
| Serving | Lift and pour from a spout | A tap or dispensing bar at the bottom; never tip it |
| Smallest batch | 2 cups on the Presto | Usually 10 to 20 cups minimum |
| Lid | Pushes on | Twists and locks into the handles |
| Extras | Usually none | Coffee level gauge, heat well cleaning tool, reset or overheat cut-out |

In short: a small percolator is for a household, an urn is for a room full of people. If you only need a dozen cups, a small machine will do a better job than an urn running near its minimum.

## What do you need to use a coffee urn?

| You'll need | Ideal | If you don't have one |
| --- | --- | --- |
| A coffee urn | One sized so your usual batch sits between its minimum and maximum lines | Borrow or hire one for a one-off event |
| Coffee | Coarse, percolator-grind coffee | Pre-ground coffee marked "For All Coffeemakers", which Hamilton Beach says is acceptable |
| A measure | A kitchen scale, using the gram amounts below | A standard measuring cup, as the makers' charts use |
| Paper filters | Optional; Hamilton Beach's BrewStation guide allows a flattened paper filter in the basket | Wet the basket well, which helps keep fine particles out |
| A cleaning tool | The urn's heat well cleaning tool | A heavy-duty scouring pad, for the heat well only |
| A socket | Its own circuit, with nothing else high-wattage on it | Plug kettles and other urns into a different circuit |

## How much coffee do you put in a coffee urn?

Here's **Hamilton Beach's chart for its commercial urns**, which comes in 40, 60 and 100-cup sizes. It's the most complete chart I found, and it gives grams as well as measuring cups:

| Urn filled to | Water | Ground coffee |
| --- | --- | --- |
| 20 cups | 3.0 litres | 1½–2 measuring cups (110–147 g) |
| 40 cups | 5.9 litres | 3–3½ measuring cups (221–257 g) |
| 60 cups | 8.9 litres | 4–4½ measuring cups (294–331 g) |
| 80 cups | 11.8 litres | 5¼–5¾ measuring cups (386–423 g) |
| 100 cups | 14.8 litres | 6½–7 measuring cups (478–515 g) |

Its **45-cup household urn** uses a little less per cup:

| Urn filled to | Water | Ground coffee |
| --- | --- | --- |
| 15 cups (minimum) | 2.2 litres | ¾ measuring cup (75 g) |
| 25 cups | 3.6 litres | 1¼ measuring cups (125 g) |
| 35 cups | 5.0 litres | 1¾ measuring cups (175 g) |
| 45 cups (maximum) | 6.4 litres | 2¼ measuring cups (225 g) |

Other makers are in the same area. The stainless steel 407CCU manual suggests 2 measuring cups for 28 to 30 cups and 2½ for 42 to 50. At full capacity, Hamilton Beach's numbers work out at about **1 g of coffee to 28–31 g of water**. That's a lot weaker on paper than a [drip coffee maker](https://dailyextraction.com/methods/automatic-drip/), but the coffee passes through the grounds many times instead of once.

All of these are starting points. Hamilton Beach says coffees vary between brands and the amount should be adjusted to your preferred strength. **Measure by the cup marks on the urn**, not by how many people are coming: a "cup" is 5 oz, and a mug holds far more.

## What grind should you use in a coffee urn?

Use a **coarse grind**. Hamilton Beach recommends coffee ground for percolators, says ordinary "For All Coffeemakers" coffee is acceptable, and warns that finely ground coffee can make the basket overflow and leave grounds in the coffee. The 407CCU manual says the same in slightly different words: avoid drip or finely ground coffee, and grind your own beans to medium coarseness, never powder.

![Chart of coffee grind sizes from extra fine to extra coarse, with coarse highlighted for a coffee urn](https://dailyextraction.com/diagrams/grind-size.svg#coarse "Where a percolator urn sits on the grind scale: coarse, so the basket doesn't flood.")

## How long does a coffee urn take to brew?

Longer than you'd think, so plan ahead. Makers give these figures:

| Urn | Brewing time given by the maker |
| --- | --- |
| Hamilton Beach 40-cup and 45-cup | About 1 minute per cup |
| Stainless steel 407CCU (30, 46 and 100 cups) | About 1½ minutes per cup |
| West Bend 33600 (40 to 100 cups) | Faster than 1 cup per minute |
| Hamilton Beach commercial (40 to 100 cups) | Starts percolating within 8 minutes |

The 407CCU manual adds that voltage changes and the temperature of the water you start with will change the time. Hamilton Beach, Nesco and the 407CCU manual all ask for **cold water**, so don't try to speed things up by filling from a hot tap.

## How do you use a coffee urn, step by step?

These steps follow the **Hamilton Beach** guides, with notes from the others:

1. **Wash it before first use**: the inside of the urn, the basket and the stem, in warm, soapy water.
2. **Fill with cold water** to the mark for your cup count, between the minimum and maximum lines. Most urns have the marks inside the tank, and many have a coffee level gauge on the outside.
3. **Seat the stem in the heat well.** On Hamilton Beach's commercial urns, check the spring is on the pump tube first. The 407CCU manual says to position it but not force it.
4. **Wet the basket**, slide it onto the stem and add the coffee. Keep grounds out of the top of the stem.
5. **Lock the lid** by turning it until the tabs engage in the handles.
6. **Plug in.** On some models you plug the cord into the urn first, then the wall. The Nesco CU-30 also has a power switch to turn on.
7. **Wait for the ready light.** Percolating stops and the urn holds the coffee at serving temperature until you unplug it.
8. **Serve from the tap.** Press the cup against the dispensing bar, or use the faucet lever. Hamilton Beach warns not to tip the urn to pour, which can clog the filter at the tap with grounds.

## How long can a coffee urn keep coffee warm?

An urn **keeps the coffee hot until you unplug it**; that's how Hamilton Beach, Nesco and the 407CCU manual all describe it. The catch is flavour. Hamilton Beach says that if coffee will be kept warm for a long time, you should **remove the basket and stem** once brewing finishes, so bitter oils from the grounds don't spoil it. The 407CCU manual goes further and says to remove the basket and grounds as soon as the cycle is complete.

To **reheat** coffee that's gone cool, Hamilton Beach says to take out the basket and stem, lock the lid and plug in for 20 to 60 minutes depending on how much is left. Don't reheat if fewer than 20 cups remain.

## Can you heat water for tea in a coffee urn?

Yes. Hamilton Beach's guides include a "to heat water" setting for tea, hot chocolate and instant coffee: fill with cold water, lock the lid and let it run one cycle. The guides differ on the parts. The 45-cup guide says to leave out the basket and stem, as water heats best without them. The BrewStation 40-cup guide says to fit them. Follow the guide for your model.

Just don't swap between jobs without washing it out. In Britain especially, "urn" often means a **tea urn**, which Wikipedia describes as a heated metal container for brewing tea or boiling water in quantity, with a tap near the base like a samovar. Many of those are hot-water boilers with no basket at all, so check yours actually has a stem and basket before you add coffee.

## Why is my coffee urn not brewing, weak or leaking?

| Problem | Likely cause | Fix |
| --- | --- | --- |
| Urn won't brew, or stops brewing | Stem not seated in the heat well, or mineral build-up | Reseat the stem; descale and clean the heat well (Hamilton Beach) |
| Urn won't heat at all | Not plugged in firmly, or the overheat cut-out has tripped | Check the plug; on the Nesco CU-30, unplug, let it cool and press the reset button underneath |
| Coffee too weak | Not enough coffee for the cup count | Use more coffee, following the chart for the water level |
| Grounds in the coffee | Grind too fine, basket not wetted, or urn tipped to pour | Use percolator grind, wet the basket, serve only from the tap |
| Basket overflows | Coffee ground too fine | Switch to a coarse or percolator grind |
| Tap leaks or drips | Residue under the tank seal, or a loose seal or nut | Clean and tighten the seal or filter assembly; on the 407CCU, tighten the nut inside the urn |
| Coffee hard to dispense | Build-up around the tap or seal | Clean it, or run a water and vinegar cycle |
| Coffee tastes bitter or stale | Grounds left in, or old oils on the parts | Lift the basket out after brewing; clean the stem and use a coffee-stain remover |

## Common coffee urn mistakes

- **Plugging it in empty.** The manuals all warn against it; Nesco says it can damage the heating element. Water first, always.
- **Brewing below the minimum line.** Use a smaller coffee maker for small groups.
- **Filling with hot water.** Makers ask for cold water, and the timings assume it.
- **Counting mugs, not cups.** A 100-cup urn makes 100 small 5 oz cups, not 100 mugs.
- **Leaving the grounds in for hours.** Take the basket and stem out once it's brewed.
- **Opening the lid mid-brew.** Hamilton Beach and Nesco both warn that scalding can occur.
- **Ignoring the heat well.** A dirty well is a common reason an urn stops brewing.

## How do you clean and descale a coffee urn?

After **every use**, unplug, let it cool, then wash the inside and the basket, stem and lid in warm, soapy water. Never immerse the urn body, base or cord. A few model-specific tips from the manuals:

- **Clean the tap.** Hamilton Beach suggests running hot soapy water through the spout, then clean hot water. The 407CCU manual says to run hot water through the faucet after each use.
- **Brush the stem.** A long, narrow brush clears the pump tube. The 407CCU manual says mineral deposits there can impair the urn's operation and old oil affects the next pot.
- **Scrub the heat well.** Hamilton Beach and the 407CCU manual both say to clean it with the cleaning tool or a heavy-duty scouring pad. The 407CCU manual warns that deposits can eventually make the tube stick in the well and break.
- **Go gently elsewhere.** Hamilton Beach says no abrasive cleaners on the rest of the urn, and Nesco says no scouring pads or bicarbonate of soda, which can pit and permanently discolour the metal.
- **Don't dry the inside with a cloth**, says Hamilton Beach, as lint may stay behind. Store the urn with the lid off or upside down, as your guide says.

**To descale**, Hamilton Beach says every 15 to 20 brews, or more often in hard-water areas. The 407CCU manual says every two weeks if the urn is used daily.

| Maker | Descaling mix | Method |
| --- | --- | --- |
| Hamilton Beach | Equal parts cold water and white vinegar (6 cups of each in the 40-cup urn) | Run one cycle with the stem and basket fitted, stand 15 minutes, drain through the tap |
| 407CCU manual | 1 quart each of water and distilled vinegar, plus 2 cups of vinegar for heavy scale | Run a cycle with the stem and empty basket, stand 10–15 minutes, drain |
| Nesco CU-30 | Cold water with several tablespoons of vinegar or cream of tartar | Heat for about 10 minutes, switch off, drain and clean |

Hamilton Beach also suggests **cream of tartar** (2 tablespoons plus 1 teaspoon in a full urn, run for one cycle) to lighten discoloured metal inside.

## What about brew-through (drip) coffee urns?

Not every urn percolates. Big **commercial twin urns** work like a giant [drip coffee maker](https://dailyextraction.com/methods/automatic-drip/). Grindmaster's Twin Space Saver Urn heats fresh water in a coil inside the urn, then a spray arm showers it over coffee in a paper-lined brew basket, and the coffee collects in a stainless liner. Its liners hold 3, 6 or 10 gallons, with brew times of 6, 9 and 14 minutes. BUNN's U3 is another 3-gallon twin automatic urn.

These are plumbed in (Grindmaster's has a 3/8 inch water inlet and refills itself), and BUNN lists its U3 for a 120/240 V supply, so they're fixed catering kit, not something you borrow for a parish coffee morning. The water goes over the coffee once instead of recirculating, as in a drip machine.

## Which coffee urn should I buy?

- **Capacity.** Buy for your usual crowd. A batch near the middle of the range is easier than one at the minimum, and a 5 oz cup is smaller than you think.
- **Minimum batch.** Check the smallest amount it will brew: 10 cups on Hamilton Beach's 40-cup BrewStation, 15 on its 45-cup, 20 on its commercial urns.
- **Household or commercial.** Hamilton Beach's 45-cup urn and the Nesco CU-30 are sold for household use, and Nesco's warranty doesn't cover commercial use. For daily use in a café, church or office, a commercial model is the safer bet.
- **Power.** Nesco's CU-30 is 950 W; the 407CCU urns are 1,000 W at 30 and 46 cups and 1,500 W at 100. Hamilton Beach says not to run another high-wattage appliance on the same circuit.
- **Serving.** A two-way faucet that locks open (like West Bend's and the 407CCU's) makes filling jugs quicker. A coffee level gauge saves lifting the lid.
- **Spare parts.** Stems, baskets, seals and lids get lost or worn. Hamilton Beach lists phone numbers for parts in its guides.

## A short history of the coffee urn

- **1839:** James Vardy and Moritz Platow are granted an English patent on a kind of urn "percolator" using the vacuum process, according to Ukers.
- **Early 1900s:** Landers, Frary & Clark of Connecticut, maker of the Universal brand, launches an electric percolator, iron, toaster and coffee urn as electricity spreads across the United States, Wikipedia says. Electric percolators were in production by at least the first decade of the 1900s.
- **1922:** Ukers's *All About Coffee* pictures a "Universal Electric Urn" among the coffee makers used in the United States. He writes that most restaurant urns were still "operated with bags", with the brew repoured until it had passed through the coffee twice, and that urns with water jackets kept the coffee at an almost constant temperature.
- **1940s or earlier:** automatic percolators, which turn down the heat when the coffee is ready, are on sale, according to Wikipedia.
- **Today:** Wikipedia notes that large percolators, called coffee urns, are often used at offices, cafeterias, community events and church gatherings, long after small percolators gave way to drip machines in the 1970s.

## What safety rules matter with a coffee urn?

An urn holds litres of near-boiling coffee, so the manuals are strict:

- **Use it on a flat surface, away from the edge** of the table, and keep the cord from hanging over the side.
- **Take extreme care moving it** with hot liquid inside, as Nesco and the 407CCU manual warn.
- **Lock the lid** before plugging in, and don't open it during brewing.
- **Use oven gloves** for the lid, basket and stem: Hamilton Beach warns the metal parts will be hot.
- **Never plug it in empty**, and never immerse the base, cord or plug.
- **Extension leads** must be rated at least as high as the urn, laid so no one can trip over or pull them.
- **Supervise children closely** near it, and don't use it outdoors (Hamilton Beach, Nesco).

*General guidance only, not a substitute for your urn's manual. Follow the maker's instructions and warnings for your own model.*

## Coffee urn vs other methods

- **[Electric percolator](https://dailyextraction.com/methods/electric-percolator/):** the same cycle in a jug-sized pot for a household.
- **[Stovetop percolator](https://dailyextraction.com/methods/stovetop-percolator/):** the original, on a hob or campfire, timed by eye.
- **[Automatic drip coffee maker](https://dailyextraction.com/methods/automatic-drip/):** single-pass brewing, like a drip urn in miniature.
- **[Cowboy coffee](https://dailyextraction.com/methods/cowboy-coffee/):** another way to make a big pot with almost no kit.
- **[Freeze-dried instant](https://dailyextraction.com/methods/freeze-dried-instant/):** what many urns end up serving, with hot water from the urn.

Explore more machine methods in the [machine chapter](https://dailyextraction.com/methods/machine/).

## Words used in this guide

- [Immersion vs percolation](https://dailyextraction.com/glossary/immersion-vs-percolation/): Immersion brewing steeps all the coffee in all the water at once, as a French press does.
- [Total dissolved solids (TDS)](https://dailyextraction.com/glossary/tds/): Total dissolved solids (TDS) measures how much coffee is dissolved in the cup, shown as a percentage.
- [Body](https://dailyextraction.com/glossary/body/): Body is how heavy and textured coffee feels in your mouth, from light and tea-like to thick and syrupy.

## FAQs

### How much coffee do I put in a 100-cup coffee urn?

Hamilton Beach’s commercial urn guide suggests 6½ to 7 measuring cups of ground coffee, about 478 to 515 g, for 100 cups (14.8 litres of water). For 40 cups it suggests 3 to 3½ measuring cups, about 221 to 257 g. Adjust to taste, as coffees vary.

### How long does a coffee urn take to brew?

Allow about one minute per cup. That’s Hamilton Beach’s guidance for its 40-cup and 45-cup urns, so a full 45-cup batch takes around 45 minutes. One stainless steel urn manual says about 1½ minutes per cup, and West Bend says its 100-cup urn brews faster than a cup a minute.

### How big is a cup on a coffee urn?

Usually 5 US fluid ounces, about 150 ml. Hamilton Beach’s commercial urn guide defines one cup as 5 ounces (150 ml), so a 100-cup urn holds about 14.8 litres. That’s a small cup, not a mug, so plan on fewer servings if people use big mugs.

### Can you make a small batch in a big coffee urn?

Only down to the urn’s minimum mark. Hamilton Beach’s 45-cup urn needs at least 15 cups, its 40-cup BrewStation urn at least 10, and its commercial urns at least 20. The makers say you must brew at least that much, so use a smaller percolator or drip machine instead.

### How do you descale a coffee urn?

Hamilton Beach says every 15 to 20 brews, or more often with hard water: fill the urn with equal parts cold water and white vinegar, fit the stem and empty basket, and run a full cycle. Let it stand 15 minutes, drain it through the tap, let it cool, then wash as normal.

### Can you reheat coffee in a coffee urn?

Yes, within limits. Hamilton Beach says to remove the basket and stem, lock the lid and plug the urn in for 20 to 60 minutes, depending on how much coffee is left. Don’t reheat if fewer than 20 cups remain in the urn.

## Sources

- [Hamilton Beach Commercial Coffee Urn (40, 60 and 100 cup) use and care guide](https://useandcares.hamiltonbeach.com/files/840277700.pdf)
- [Hamilton Beach 45-Cup Coffee Urn use and care guide](https://useandcares.hamiltonbeach.com/files/840294102.pdf)
- [Presto 6-Cup Stainless Steel Coffee Maker instructions](https://www.manualsdir.com/manuals/171778/presto-coffeemaker.html?page=2)
- [Hamilton Beach BrewStation 40-Cup Urn use and care guide](https://useandcares.hamiltonbeach.com/files/840172406.pdf)
- [NESCO 30 cup Coffee Urn (model CU-30) user manual](https://images.thdstatic.com/catalog/pdfImages/97/97b57a55-11d0-4453-bd49-2e75b8da5845.pdf)
- [Stainless Steel Single Wall Coffee Urn manual (models 407CCU30, 407CCU50, 407CCU100)](https://www.webstaurantstore.com/documents/pdf/coffee_urn_manual.pdf)
- [West Bend 33600 100-cup commercial urn](https://westbend.com/collections/coffee-makers/products/33600-100-cup-commercial-urn)
- [Twin Space Saver Urn specification sheet (models 8103, 8106, 81010)](https://cdn.beedash.com/GrindmasterCecilware/436fb82134d85b276d4ddce5965602ba5cd43d2f.pdf)
- [U3 3 gal twin automatic electric coffee urn](https://commercial.bunn.com/20500.0001)
- [All About Coffee, chapter 36: Preparation of the Universal Beverage](https://ukersallaboutcoffee.wordpress.com/chapter36/)
- [Coffee percolator](https://en.wikipedia.org/wiki/Coffee_percolator)
- [Landers, Frary & Clark](https://en.wikipedia.org/wiki/Landers,_Frary_%26_Clark)
- [Urn (tea urn)](https://en.wikipedia.org/wiki/Urn)