What Is the Most Likely Cause of a Percolator's Failure to Pump Water?

How Percolator Pumps Work

• The basket of your percolator has a tube or round opening where the pump stem is inserted. The basket itself has small holes that prevent coffee grounds from escaping while allowing the water to pass through. The pump stem is typically a long tube that sits in the middle of the pot and extends from the base up to the bottom of the lid. This stem supports the basket. On the stem is a flange, which the basket is seated on. Percolator pumps rely on air bubbles caused when the water boils, and the natural tendency for bubbles to rise upward. The base of the stem concentrates this flow toward the opening of the tube, which is smaller in diameter than the water bubbles. They pass through this opening and carry water up toward the basket, where it is dispersed over the coffee grounds.

Mineral Deposits

• Over time, particularly with hard water, mineral deposits such as calcium can build inside your percolator pump system. If these deposits clog the pump stem, your percolator will be unable to pump water to the basket. To remove buildup of mineral deposits, fill the percolator with equal amounts cold water and white vinegar. Assemble as you would if you were making a pot of coffee with stem, basket, spreader and the lid in their proper positions. Plug in the percolator and let it complete one perk cycle. When it stops, allow it to sit for about 15 minutes and then unplug and drain the contents. Clean the interior and the parts thoroughly and rinse with clean water. If you use your percolator daily, clean with vinegar about once each week to prevent mineral deposit buildups.

Washer

• The washer at the base of the pump tube must always float freely. If it is clogged with coffee grinds or scale, it cannot do this and that can interfere with your percolator’s ability to pump water properly. Clean the base of the pump with hot water to remove debris and ensure that there is no material between the base of the pump stem and the washer. To clean away calcium or hard water scale, soak the washer in vinegar and rinse thoroughly with water before placing it back in your percolator.

Positioning

• The pump stem or tube must be properly seated in your percolator in order to function properly. If it is crooked, bent or touching the side, this can prevent the bubbles from entering the opening at the bottom, thus making it impossible for it to pump water. Remove the percolator lid and hold the top of the pump stem as you place it into the percolator. Make sure the stem is seated vertically so that it is in the center of the heating unit.