my coffee maker is leaking water all over the counter from the bottom when it brews

Diagnosis

The Black+Decker CM1160B typically leaks from the base due to a failure in the closed-loop water delivery system. Most commonly, this is caused by a hairline fracture in the plastic water reservoir or a degradation of the rubber O-ring seal located at the base of the reservoir where it connects to the heating element. When water is pumped into the heating tube, any breach in this seal or a crack in the plastic housing allows water to bypass the internal plumbing and pool at the bottom of the machine, eventually leaking onto your counter. Another frequent cause is "overflow leakage." If the brew basket is overloaded with coffee grounds or the filter is folded improperly, water cannot flow through the grounds quickly enough. This causes the water to back up and overflow the brew basket's rim, running down the internal chassis and exiting through the bottom of the unit. You can confirm this by running a brew cycle without coffee or a filter; if the leak stops, the issue is overflow. If it continues to leak from the bottom despite an empty basket, you have a structural seal failure or a cracked internal hose.

How to Fix It

Follow these steps to isolate and resolve the leak:

1. Unplug the unit and remove the water reservoir. Fill the reservoir to the 12-cup mark and let it sit in a sink for 10 minutes. If you see drips forming on the bottom of the plastic tank, the reservoir is cracked and must be replaced.
2. Inspect the rubber gasket (O-ring) at the bottom of the reservoir. This is the small black ring that seals the tank to the machine. If it is pinched, dry, or missing, the seal will fail. Remove the ring, clean it with warm soapy water, and apply a tiny amount of food-grade silicone lubricant to ensure a tight seal.
3. Check the brew basket alignment. Ensure the basket is seated flush against the drip-stop valve. If the basket is tilted, water will spill over the side rather than flowing into the carafe.
4. Clean the drip-stop valve. Use a toothpick or a small brush to clear any coffee grounds stuck in the valve at the bottom of the brew basket. A clogged valve causes water to back up and leak over the edges.
5. Verify the carafe is centered. If the carafe is not pushed firmly against the drip-stop, water will spray outward and run down the sides of the machine to the base.

If That Didn't Work

• Internal Hose Disconnection: The internal silicone tubing that carries water from the reservoir to the heating element can slip off its barb or develop a pinhole leak due to heat fatigue. This requires removing the base screws to open the chassis. Locate the clear silicone hose and ensure the metal tension clamps are tight. If the hose is cracked, it must be replaced with high-temperature food-grade silicone tubing.
• Scaling Buildup: Mineral deposits (calcium) can clog the internal narrow-bore tubes, increasing pressure and forcing water out of the weakest seal. Perform a deep descale using a 50/50 mixture of white vinegar and distilled water. Run a full brew cycle, let it sit for 30 minutes, and then run two cycles of plain water to flush.
• Cracked Heating Element Housing: In rare cases, the plastic housing surrounding the aluminum heating tube develops a stress crack. If you see water bubbling up from the very center of the base during the heating phase, the internal manifold is compromised. This is generally not repairable and requires a unit replacement.

Heads Up

• Avoid using "extra-fine" or "espresso-style" grinds in this machine; they clog the filter and cause the overflow leaks mentioned in the diagnosis.
• Always use filtered water if you live in a hard-water area to prevent the calcium buildup that leads to seal failure and pressure leaks.
• Do not overfill the reservoir beyond the 12-cup line, as this can put undue pressure on the pump and seals.
• Clean the brew basket and the drip-stop valve weekly to ensure water flows freely into the carafe.