how do i clean the inside water tank on my keurig classic? it looks gross.

Clean the Hot Water Tank with a damp cloth and descale with vinegar for mineral deposits.

• Surface Cleaning: Press the PRESS TO OPEN button and lower the handle completely. The water fill lid will pop open. Inspect and clean the tank interior with a damp, lint-free cloth.
• Descaling (for white deposits): Do this every 3-6 months.
  1. Have 8 oz undiluted white vinegar and a ceramic cup ready.
  2. Fill the Hot Water Tank with the vinegar to the FILL LEVEL mark.
  3. Place the cup on the drip tray, close the lid, and run a brew cycle without a K-Cup.
  4. Pour the hot vinegar from the cup back into the tank.
  5. Start another brew, but power off just after it starts. Let it sit for 30 minutes.
  6. Run a brew cycle to empty the tank into the sink.
  7. Fill with 8 oz bottled water and run a brew cycle. Repeat this water-only brew three times to rinse.

Heads up: Spotting in the tank is normal and depends on your water's mineral content. It doesn't affect operation. Never use anything but water in the reservoir.