Tested: How to Get Mold Out of Espresso Machine Fast

By Sarah Mitchell · December 15, 2025

Immediate Action (first 5 minutes)

I still remember the morning I pulled a shot on my Breville Barista Express and saw black flecks floating in my crema. It was disgusting. If you spot mold in your water reservoir, group head, or drip tray, stop brewing immediately. Don't try to flush it out with a quick shot of hot water. That just spreads the spores into your internal boiler and ruins your coffee.

First, unplug the machine from the wall. Safety is non-negotiable when you're mixing water and electricity. Next, pull out the water tank and dump any standing water straight down the sink. Remove the portafilter, the shower screen, and the drip tray. I usually toss all these removable parts into a large plastic basin right away. This stops the mold from drying out and clinging harder to the silicone gaskets. Grab a dry microfiber cloth and wipe down the exterior surfaces to remove any visible moisture. You want the machine completely dry on the outside before you start applying liquid cleaners to the inside.

What You'll Need (tools/products)

I've tested dozens of cleaning agents over the last eight years of repairing and maintaining cafe equipment. You can't just use dish soap. It leaves a soapy residue that completely destroys the taste of your espresso. Here is my exact toolkit for eradicating mold without damaging the delicate brass and aluminum components inside your machine.

Urnex Cafiza Espresso Machine Cleaner ($15-20): This is the gold standard for backflushing. It breaks down coffee oils and organic matter where mold loves to hide.
Urnex Dezcal Descaler ($12-15): Mold often piggybacks on limescale buildup. You need this to strip the mineral deposits.
Pallo Coffeetool Brush ($10-12): The stiff bristles and angled handle let you scrub the group head without burning your knuckles on hot water.
Microfiber Cloths (Pack of 6 for $15): Keep these dedicated solely to your coffee station.
Food-Grade Silicone Lubricant ($8-10): Essential for reconditioning the group head gasket after a deep scrub.
Distilled White Vinegar ($3-5): Only for the removable plastic water tank, never the internal boiler.

Let's look at how these stack up against generic household cleaners.

Product	Best For	Price Range	My Rating
Urnex Cafiza	Internal backflushing	$15 - $20	10/10
Dawn Dish Soap	Exterior & drip tray	$3 - $5	6/10
White Vinegar	Water tank only	$3 - $5	5/10

Step-by-Step Removal (4-7 steps)

I'll be honest, this takes elbow grease. You can't just run a cleaning tablet through the machine and call it a day when active mold is present. Follow this exact sequence to kill the spores and flush them out of your Breville, Gaggia, or Rancilio.

Step 1: Deep Soak the Removable Parts

Fill a large basin with 140°F water and add one scoop of Urnex Cafiza. Drop in your portafilter, baskets, shower screen, and drip tray. Let them soak for exactly 30 minutes. The hot water and alkaline cleaner will dissolve the rancid coffee oils that the mold is feeding on. After 30 minutes, scrub every crevice with a stiff nylon brush. Rinse them thoroughly under cold tap water and set them on a drying rack.

Step 2: Sanitize the Water Reservoir

The plastic water tank is usually ground zero for mold growth. I never put this part in the dishwasher because the high heat warps the plastic and ruins the magnetic water level sensor. Instead, wash it in the sink with warm water and a few drops of mild dish soap. If you see stubborn black spots on the plastic, make a paste of baking soda and water. Scrub the spots with a sponge, let it sit for 10 minutes, and rinse. Dry it completely with a lint-free towel before reattaching it to the machine.

Step 3: Scrub the Group Head and Gasket

This is where things get messy. Turn the machine on and let it heat up to its normal brewing temperature, usually around 200°F. Lock the blind basket (the one with no holes) into the portafilter and lock it into the group head. Run the pump for 10 seconds, then stop. Use your Pallo brush to aggressively scrub the silicone gasket and the metal shower screen while the hot water drips down. The hot water softens the gunk, making it much easier to dislodge. Repeat this hot water flush and scrub cycle three times.

Step 4: Chemical Backflushing

Now we kill the internal mold. Put half a teaspoon of Cafiza powder directly into the blind basket. Lock it into the group head. Run the pump for 10 seconds, then let it sit for 10 seconds. The pressure forces the cleaning solution up into the three-way solenoid valve and the internal pipes. Do this 5 times. You'll hear the pressure release valve hiss when you stop the pump. That hissing means the cleaner is doing its job in the exhaust tube. Let the machine sit for 15 minutes so the chemicals can break down the biofilm.

Step 5: The Mega Rinse Cycle

Remove the portafilter and rinse out the dissolved cleaner. Lock the empty blind basket back in. Run the pump for 10 seconds and stop, repeating this 10 times with just plain water. This flushes the chemical residue out of the internal plumbing. Next, remove the blind basket and run plain water through the open group head for a full 60 seconds. If your machine has a steam wand, purge it into a cup of hot water for 30 seconds to clear any milk residue that might be harboring bacteria.

Step 6: Recondition and Reassemble

Mold loves dry, cracked silicone. Once the group head is completely dry, apply a tiny pea-sized drop of food-grade silicone lubricant to the gasket. Rub it in with your finger. This creates a watertight seal and prevents moisture from getting trapped behind the gasket where you can't clean it. Reattach the water tank, lock in your freshly cleaned portafilter, and pull a seasoning shot of cheap coffee to coat the internal pipes with fresh oils. Dump that shot. Your machine is now safe to use.

Alternative Methods (2-3 backup methods)

Sometimes you don't have professional espresso cleaners on hand, or you're dealing with a specific type of machine that doesn't support traditional backflushing. Here are a few backup methods I use when I'm in a pinch.

The Vinegar Tank Soak (For Non-Pump Machines)

If you have a cheap steam-driven espresso maker like a Mr. Coffee Cafe Barista, you can't backflush them. They lack the 9-bar pressure required to push cleaners through the solenoid valve. Instead, fill the water tank with a 50/50 mix of distilled white vinegar and water. Run the brew cycle until half the tank is empty. Turn the machine off and let the acidic solution sit in the boiler for 45 minutes. This kills surface mold and dissolves scale. Flush the remaining solution, then run at least three full tanks of fresh water through the machine to remove the vinegar smell.

Hydrogen Peroxide for Stubborn Tank Spots

I had a client whose water tank had thick, fuzzy green mold growing in the bottom corners. Baking soda didn't cut it. I sprayed 3% hydrogen peroxide directly onto the mold spots and let it bubble for 15 minutes. The peroxide oxidizes the mold cell walls, literally destroying them on contact. After 15 minutes, I wiped the tank out with a paper towel and washed it with warm soapy water. It's highly effective, but never run peroxide through the internal boiler of your machine.

Denture Tablets for the Drip Tray

The drip tray collects a gross mixture of spilled milk, coffee grounds, and stagnant water. It's a perfect breeding ground for black mold. When I'm too lazy to scrub it by hand, I fill the tray with warm water and drop in two Polident denture cleaning tablets. Let it fizz for 30 minutes. The effervescent action lifts the biofilm right off the plastic grates. Rinse it out, and it looks brand new. This isn't the cheapest option, but it saves my knuckles from scrubbing tight plastic grids.

Prevention Tips

Killing mold is a massive pain. Preventing it is incredibly easy if you build a solid routine. I've maintained machines in humid environments for years without a single mold outbreak by following these strict rules.

Empty the drip tray daily: Don't wait until the red float indicator pops up. Stagnant coffee water grows mold in 48 hours at room temperature. Dump it, rinse it, and dry it every single night.
Leave the water tank lid open: If you aren't making coffee for a few days, crack the lid of the water reservoir. Mold needs a dark, humid environment to thrive. Letting air circulate dries out the top layer of water and stops spores from settling.
Purge the steam wand immediately: After frothing milk for a latte, wipe the wand with a damp cloth and purge steam for 2 seconds. Milk baked onto the outside of the wand will eventually mold and flake into your next drink.
Use filtered water: Hard water creates limescale. Limescale creates microscopic rough surfaces inside your boiler. Mold spores grab onto those rough surfaces and colonize. A simple Brita filter or a BWT Bestmax system cuts down scale and removes chlorine, making your coffee taste better and your machine stay cleaner.
Run a water-only flush after every shot: Get into the habit of running 2 ounces of plain hot water through the group head after you pull your espresso. This washes away the sticky coffee oils before they can harden and become a food source for fungi.
Prep for vacations: When you go on a two-week vacation, empty the water tank completely and leave the lid off. Run a dry cloth through the drip tray and leave the portafilter unlocked so air can circulate through the group head gasket.

FAQ

Can mold in an espresso machine make me sick?

Yes, brewing through a moldy machine can introduce mycotoxins and airborne spores into your cup and kitchen. While the boiling water kills some bacteria, it doesn't destroy all heat-resistant mold spores or the toxic compounds they produce. If you have asthma or allergies, inhaling the steam from a contaminated machine can trigger severe respiratory reactions.

How often should I backflush my espresso machine?

For a home user pulling two to four shots a day, a chemical backflush every two weeks is the sweet spot. If you run a busy home setup or host weekend dinner parties where you're making twenty lattes, do it weekly. Commercial machines in cafes need to be backflushed with Cafiza every single night after closing.

Why does my espresso taste sour after cleaning?

A sour or metallic taste usually means you didn't rinse the machine thoroughly enough after using a chemical cleaner or descaler. Run at least three full water tanks through the brew head to flush out any lingering alkaline or acidic residue. Pulling a seasoning shot with cheap beans and discarding it also helps coat the internal metal with fresh, good-tasting coffee oils.

Is it safe to use bleach to clean the water tank?

I strongly advise against using bleach on any part of an espresso machine. Bleach degrades the food-grade silicone gaskets and rubber O-rings, causing them to crack and leak. It also leaves a harsh chemical odor that is nearly impossible to flush out of the porous plastic water tank, completely ruining the flavor of your coffee.