Guide · percolator

Stovetop percolator: how it works and why it over-extracts

A stovetop percolator boils water in the bottom of the pot, pumps it up a central tube and sprinkles it over a basket of grounds. The brew drains back into the same water and goes round again. That loop is what makes the percolator simple to run and easy to over-extract. Below: the loop, the makers' printed steps, and where the sources disagree on why the cup turns bitter.

Updated 2026-10-30 · sources listed at the end · no product recommendations

How the loop works

Water goes in below the basket, and coarse grounds go in the basket at the top of a removable vertical tube (Wikipedia). As the water heats, steam bubbles push hot water up the tube. It hits the underside of the lid, runs over a perforated cover that spreads it across the grounds, and drips through them back into the water below. The cycle repeats with an intermittent "perking" sound. Hanson Goodrich's 1889 US patent 408,707, the design Wikipedia calls the modern US stovetop percolator, describes the same thing: water boils, rises through the tube, falls on the coffee and drains back, so that "a continuous circulation of the water is maintained." Its history is on the brewing device timeline.

Percolator, moka pot and drip compared

All three use hot water and gravity or steam, but only one sends the brew back through the grounds.

Wide table: scroll sideways on a phone.

The SCA's brewing reference for comparison is water at 200 °F ± 5° (93.0 °C ± 3°) where it meets the coffee, 55 g/L ± 10%, and a contact time of 6–8 minutes for a coarse grind. Water boils at 212 °F (100 °C) at sea level, so a pot running at or near the boil sits above that window. At 5,000 ft water boils at about 203 °F (95 °C), per the table Wikipedia attributes to NASA; the temperature converter works out other altitudes. The moka pot works differently again; see the moka pot guide.

Why a percolator over-extracts

Extraction yield is the share of the grounds, by weight, that dissolves into the water, and the commonly agreed ideal is about 18–22% (Wikipedia, Coffee preparation). Going past it gives the "bitter, harsh, over-extracted" taste. A percolator stacks three things in that direction:

• Recirculation. Brew that has already passed through the grounds is pumped up and sent through them again. Wikipedia's percolator article says this, together with the high temperature, makes percolator coffee "particularly susceptible to overextraction."
• Heat at or near the boil. The grounds sit in brew close to boiling for the whole cycle.
• No built-in end point. A drip machine stops when its reservoir is empty and a moka pot when its boiler is, but a stovetop percolator keeps going. "Brewed coffee left continuously percolating at the boiling point will over extract, making the resulting coffee harsh and excessively bitter" (Wikipedia). Wikipedia's drip coffee article gives the percolator's "tendency to over-extract coffee" as a reason drip makers largely replaced it in the 1970s.

Where the sources disagree

Wikipedia's Coffee preparation article says "the bitter acids are released when the water has reached boiling point," which would make temperature itself the problem. Research from the UC Davis Coffee Center points elsewhere. Batali, Ristenpart and Guinard (2020) brewed drip coffee at 87, 90 and 93 °C to the same strength and extraction, and found that temperature "plays a minimal role" in the sensory profile; taste followed strength and extraction. Liang, Chan and Ristenpart (2021) found the equilibrium constant of immersion brewing insensitive to brew temperature over 80–99 °C. Neither tested a percolator or boiling water. Our reading: the clearest lever is how much the pot extracts, set by grind, perk time and the number of passes; the separate effect of the boil is not settled. Percolator users, Wikipedia notes, argue the pitfalls can be avoided by controlling the brew carefully. The brewing control chart shows how strength and extraction are measured.

Step by step, as the makers describe it

1. Wash the parts before first use (Farberware).
2. Fill with cold, fresh water to the cup markings inside the pot. Elite says keep it at least half full and never above the maximum line below the spout. The water must stay below the bottom of the basket (Wikipedia; One All).
3. Use a coarse grind. Finer grounds pass through the basket and settle in the pot; Elite says a filter disc is then required. The grind size chart shows the coarse range.
4. Dose the basket. Elite's chart for its 8-cup pot gives 4, 6 or 8 tablespoons for mild, medium or strong, and 3, 4 or 6 for 6 cups. Farberware's manual counts a cup as 5 fl oz. To work by weight instead, see tablespoons to grams and the SCA's 55 g/L.
5. Assemble: pump tube and basket on the center well, spreader on the grounds, lid on and closed (Farberware; Elite).
6. Heat on medium to medium-high (Elite) or medium (One All). For a glass pot on a coil electric stove, One All supplies a metal trivet to go between coil and pot.
7. Turn the heat down once it boils, to low or medium (Elite), and let it perk about 5–7 minutes (Elite). One All instead says to take it off the heat when the coffee reaches the color you want. Near the boil, the perking turns into a continuous gurgle (Wikipedia).
8. Take it off the heat and remove the basket and tube before serving (One All); Farberware says removing them gives the best flavor. Reheat on low heat only (Elite).

Checklist before you light the burner

• Water within the markings and below the basket; never let the pot boil dry (Elite, GSI).
• Coarse grounds, or a filter disc for finer ones.
• Lid seated; do not open it while heating (Elite, GSI).
• Burner no wider than the base; trivet for a glass pot on a coil stove.
• Potholder ready; timer set, and the perk time noted with the result.
• After brewing, move the pot off the hot burner onto a heat-resistant surface (Elite). GSI says do not try to cool it quickly.

Oils and the metal basket

Wikipedia's percolator article notes that non-pressure percolators can also take paper filters. A 2025 Swedish study (Orrje et al.) measured cafestol, an oil-borne diterpene, at about 90 mg/L in percolator and French press coffee, reported together, against a median of 12 mg/L in five home-brewed paper-filtered coffees. What those compounds do and how filters hold them back is on the coffee filters page.

Terms

Percolation

Water passing through a bed of grounds under gravity, used in both percolators and drip brewing (Wikipedia). The stovetop percolator repeats it. More terms are in the glossary.

Recirculation

Brew that has passed the grounds returns to the reservoir and goes through them again; Goodrich's "continuous circulation."

Perking

The intermittent sound of water rising up the tube; it becomes a continuous gurgle near the boil (Wikipedia).

Over-extraction

Dissolving more of the grounds than the 18–22% ideal, tasting bitter and harsh (Wikipedia).

Steps differ by pot: follow your model's instructions, and treat the perk time above as one maker's starting point, not a standard.