Why Is Coffee Maker Leaking? (6 Causes & Fixes)

A leaking coffee maker is messy and potentially damaging to your counter and cabinets. The good news: most leaks have simple causes that you can diagnose and fix yourself. Here are the six most common reasons a coffee maker leaks and how to fix each one.

1. Overfilled Water Reservoir

Most common cause. Filling the reservoir above the MAX line causes water to overflow during heating as the water expands.

Fix: Never fill above the MAX line. If you've overfilled, remove the reservoir, pour out the excess, and reseat it. The MAX line exists for a reason — water expands when heated.

2. Cracked or Damaged Water Reservoir

Hairline cracks in the reservoir are easy to miss but cause a slow, steady drip that appears to come from the bottom of the machine.

Fix: Remove the reservoir and fill it with water over a sink. Watch for drips. If you find a crack, the reservoir needs replacement. Most manufacturers sell replacement reservoirs as spare parts.

3. Loose or Damaged Reservoir Seal

The rubber seal or gasket where the reservoir connects to the machine can wear out, crack, or become misaligned over time, causing leaks at the connection point.

Fix: Remove the reservoir and inspect the seal. Clean it with a damp cloth — debris can prevent a proper seal. If the gasket is cracked or deformed, it needs replacement. Contact the manufacturer for the correct part.

4. Clogged Internal Lines (Overflow Leak)

Mineral buildup can partially block internal water lines, causing pressure to build up and water to find alternative exit points — often appearing as a leak from the bottom or sides of the machine.

Fix: Descale the machine. Use the Essential Values Universal Descaling Solution for Keurig and Nespresso machines, or a 1:1 vinegar and water solution for standard drip coffee makers. See our descaling guide for full instructions.

5. Misaligned or Overfilled Filter Basket (Drip Coffee Makers)

If the paper filter collapses or folds over during brewing, it can block the flow of coffee into the carafe, causing the basket to overflow and leak down the sides of the machine.

Fix:

• Make sure the paper filter is properly seated and opened fully before adding grounds
• Don't overfill the filter basket — leave at least 1 cm of space at the top
• Use the correct filter size for your machine
• Consider switching to a reusable mesh filter, which can't collapse

6. Carafe Not Properly Seated (Drip Coffee Makers)

If the carafe isn't fully pushed onto the warming plate, the drip stop mechanism may not open properly, causing coffee to overflow from the filter basket.

Fix: Ensure the carafe is pushed all the way back onto the warming plate until it clicks or sits flush. Never remove the carafe mid-brew unless your machine has a pause-and-pour feature.

Quick Diagnostic: Where Is the Leak Coming From?

When to Replace the Machine

If the leak is coming from internal components (pump, boiler, or internal hoses) and the machine is more than 4–5 years old, replacement is usually more practical than repair. Internal component leaks require disassembly and are difficult to fix without technical knowledge.

Most coffee maker leaks are caused by overfilling, a misaligned filter, or mineral buildup — all fixable in under 10 minutes. Work through the checklist above before assuming the machine needs replacement.