water is leaking from the bottom of the machine onto my counter every time i run a cycle.

Diagnosis

Water pooling beneath the Cuisinart DGB-900BC is rarely a result of a simple spill or overflow; it is almost always a failure of the internal fluid delivery system. The primary culprit is the silicone inlet tubing that bridges the gap between the water reservoir and the heating element (thermoblock). Over time, the constant thermal expansion and contraction caused by the brewing cycle causes the silicone to degrade, develop hairline fractures, or slip off its barb fitting entirely. When the pump engages, it creates pressure that forces water through these cracks. Because the leak occurs internally, the water drips down the chassis and collects at the lowest point of the machine, creating a puddle on your countertop. You can confirm this by placing a piece of dry paper towel under the unit and running a short brew cycle; if the towel saturates quickly while the machine is running, the internal seal is compromised. If the leak only occurs during the "grind" phase, it is likely a seal failure in the bean-to-brew transition, but 90% of bottom-leaks are tubing failures.

How to Fix It

To resolve this, you must access the internal plumbing. You will need a Phillips #2 screwdriver and a replacement high-temperature silicone tube (approx. 4mm inner diameter) if the existing one is cracked.

1. Unplug the unit from the wall and remove the brew basket and carafe to clear the workspace.
2. Remove the screws located at the rear and bottom of the chassis. Carefully lift the outer plastic shell upward and backward to avoid snapping the plastic clips.
3. Locate the clear/white silicone tubing running from the bottom of the water reservoir to the aluminum heating block.
4. Inspect the tube for "clouding" or visible splits. Check specifically where the tube meets the plastic barb fittings; this is where most slips occur.
5. If the tube has slipped, push it firmly back onto the barb. If it is cracked, cut the damaged section away using a sharp blade or replace the entire length of the tube.
6. Secure the connection using a small, heat-resistant zip tie or a silicone pinch clamp to ensure the pressure of the pump doesn't push the tube off again.
7. Reassemble the shell, ensuring no wires are pinched between the plastic casing and the base.
8. Perform a "dry run" (without the shell) using only water to verify that no droplets are escaping the fittings before final closure.

If That Didn't Work

• Check the Reservoir Gasket: Inspect the rubber O-ring at the base of the water tank. If the gasket is pinched or cracked, water will leak down the outside of the tank and pool at the bottom. Replace the O-ring and apply a tiny amount of food-grade silicone lubricant to ensure a tight seal.
• Inspect the Thermoblock Seal: If the leak is coming from the heating element itself rather than the tubes, the internal gasket of the thermoblock may have failed. This usually manifests as a slow drip even after the machine is turned off. This requires a full replacement of the heating assembly.
• Valve Clog/Backpressure: If the brew basket is clogged with too many fine coffee grounds, it creates backpressure that can force water out of the weakest seal in the system. Deep clean the brew head with a needle to ensure there are no blocked holes causing pressure buildup.
• Cracked Water Tank: Examine the plastic of the reservoir for hairline cracks, especially near the bottom. Use a flashlight to look for "stress whitening" in the plastic. If the tank is cracked, it must be replaced as epoxy is not food-safe for high-heat applications.

Heads Up

• Scale Buildup: Calcium deposits can create "micro-leaks" by forcing seals to expand. Descale your machine every 60-90 days using a 50/50 white vinegar and water solution to prevent pressure spikes.
• Avoid Overfilling: Never fill the reservoir past the "Max" line; overfilling can put undue stress on the intake valves and lead to premature tubing failure.
• Electrical Safety: Always ensure the unit is completely dry before plugging it back in after a repair. Water on the internal circuit board can cause a permanent short circuit.
• Tube Quality: If replacing tubing, ensure you use "Food Grade High-Temp Silicone." Standard vinyl tubing will melt when it touches the thermoblock.