water is leaking from the bottom of my lattissima one, underneath the machine

Diagnosis

The Lattissima One typically leaks from the bottom due to a failure in the primary water intake seal or a buildup of scale that forces water through the internal overflow bypass. Most commonly, the silicone O-ring at the base of the water tank has become warped, cracked, or displaced, allowing water to seep directly into the machine's chassis rather than entering the pump system. This creates a pool of water underneath the machine that often mimics a pump failure. Another frequent cause is a blockage in the capsule extraction area. If coffee grounds or mineral scale build up around the brewing head's rubber gasket, water cannot flow cleanly into the cup and instead redirects down the internal side-walls of the machine, eventually dripping out of the bottom casing. You can confirm this by running a "cleaning cycle" without a capsule; if the leak persists, it is likely the tank seal. If it only leaks during brewing, it is a gasket or blockage issue.

How to Fix It

Follow these precise steps to isolate and resolve the leak:

1. Inspect and Reset the Water Tank Seal: Lift the water tank completely out of the machine. Locate the circular silicone gasket at the bottom center of the tank. Use a damp microfiber cloth to wipe away any slime or mineral deposits from both the gasket and the receiving valve on the machine's base. Ensure the gasket is seated flush; if it is pinched or twisted, gently pull it out and re-insert it using a plastic tool.
2. Clear the Capsule Chamber: Open the lever and remove any remaining capsule. Use a toothbrush to scrub the black rubber seal surrounding the brewing head. Specifically, look for "coffee puck" residue that may be preventing a tight seal between the capsule and the machine.
3. Deep Clean the Drip Tray Assembly: Slide out the drip tray and the used capsule container. Check the rear of the tray for any debris or spilled coffee that might be blocking the drainage holes, causing water to overflow the internal reservoir and leak from the bottom.
4. Perform a High-Pressure Flush: Fill the tank to the MAX line. Without inserting a capsule, close the lever and run three consecutive "Lungo" cycles. This clears air pockets and flushes out any loose scale that might be causing internal turbulence and leaking.

If That Didn't Work

• Perform a Full Descaling Cycle: If the leak is caused by internal pressure buildup due to calcium deposits, you must use a Nespresso descaling kit. Fill the tank with one packet of descaling solution and 1 liter of water. Run the descaling program (refer to the specific button sequence for your model) to clear the internal thermoblock. Scale buildup can cause micro-cracks in the internal tubing over time.
• Replace the Water Tank Gasket: If the silicone ring at the bottom of the tank shows visible cracks or has lost its elasticity (feels "mushy"), it must be replaced. You can source a compatible silicone O-ring for the Lattissima One to restore the airtight seal.
• Check the Milk Frother Connection: Occasionally, a leak at the bottom is actually milk or water leaking from the milk carafe connection point and traveling down the internal chassis. Ensure the milk tank is locked firmly into place and the connection valve is free of dried milk residue.
• Internal Tube Inspection: If you are comfortable opening the casing, check the silicone tubing leading from the pump to the thermoblock. Over time, the tension clips can loosen, causing a slow drip that collects at the base of the machine.

Heads Up

• Avoid Distilled Water: Using distilled water can actually degrade the rubber seals faster than tap water. Use filtered water to prevent scale while maintaining seal integrity.
• Empty the Capsule Bin Daily: A full capsule container can cause back-pressure in the drip tray, leading to "invisible" overflows that leak from the bottom of the machine.
• Avoid Over-Tightening: When cleaning the brewing head, do not use harsh chemicals or abrasive scrubbers on the rubber gasket, as this creates micro-tears that lead to permanent leaks.
• Monthly Deep Clean: Once a month, remove the water tank and wipe the receiving valve with a vinegar-soaked cloth to prevent mineral crystallization.