how do i clean the inside water tank on the kbv select? it's getting cloudy and i see some sediment.

Diagnosis

The cloudiness and sediment you are seeing in the KBGV Select reservoir are the result of calcium carbonate buildup (limescale) and the accumulation of a biological film. Because the Moccamaster uses a high-heat copper boiling element, minerals in your tap water are concentrated and precipitate out of the solution, clinging to the walls of the polypropylene tank and the intake valve. Over time, these minerals create a porous surface that traps organic matter, leading to the "cloudy" appearance. To confirm this is mineral scale and not a structural failure of the plastic, rub a small area of the sediment with a cotton swab dipped in white vinegar. If the sediment dissolves or clears instantly, you are dealing with calcium buildup. If the residue remains or the plastic feels pitted, you may have an issue with hard water etching, though this is rare with the high-grade materials used in the 53941 model. This buildup can eventually clog the intake, causing the machine to brew slower or trigger the automatic shut-off prematurely due to overheating.

How to Fix It

Since the KBGV Select reservoir is integrated and not fully removable for dishwasher cleaning, you must perform a targeted manual scrub followed by a chemical descale.

1. Unplug the machine and allow it to cool completely to avoid warping the plastic or causing thermal shock to the copper element.
2. Mix a cleaning solution of 1 part distilled white vinegar and 2 parts warm (not boiling) filtered water. Pour this into the reservoir until it is approximately half full.
3. Using a long-handled, soft-bristle bottle brush or a dedicated reservoir brush, gently scrub the interior walls. Focus specifically on the bottom corners and the area surrounding the water intake valve where sediment tends to settle in a thick ring.
4. Rinse the reservoir three times with fresh, cold water to remove all loosened debris and vinegar residue.
5. To clear the internal plumbing and the copper element, fill the reservoir to the 1.25L max line with a mixture of 50% water and 50% commercial descaling solution (or a citric acid-based cleaner).
6. Turn the machine on and allow it to brew a full cycle. Once the cycle finishes, turn the machine off and let the solution sit inside the heating element for 30 minutes.
7. Run two full cycles of plain, filtered water through the machine to ensure no chemical taste remains in the brew head.

If That Didn't Work

• Deep Chemical Soak: If the cloudiness persists, fill the reservoir with a concentrated citric acid solution (2 tablespoons of citric acid powder dissolved in 1 liter of warm water). Let this soak for 4-6 hours without running the machine. This is more aggressive than vinegar and will break down stubborn calcium bonds that a brush cannot reach.
• Mechanical Agitation: For heavy sediment at the very bottom, add a handful of coarse sea salt to the reservoir with warm water. Use a stirring rod to agitate the salt against the walls; the granules act as a mild abrasive to scrub away biofilm without scratching the polypropylene.
• Intake Valve Clearing: If the water flow is still sluggish, the sediment may be trapped in the intake valve at the base of the tank. Use a thin pipe cleaner or a flexible nylon brush to gently probe the intake opening to clear any solidified mineral chunks.
• Water Softener Implementation: If the cloudiness returns within two weeks, your local water hardness exceeds the machine's tolerance. Switch to using distilled water or a zero-water filtration pitcher to prevent future mineral precipitation.

Heads Up

• Never use steel wool, scouring pads, or harsh bleach inside the reservoir, as these will scratch the plastic, creating microscopic grooves where bacteria and minerals will accumulate even faster.
• Avoid using "coffee machine cleaners" that contain high concentrations of sodium hydroxide, as these can degrade the seals in the KBGV Select's copper heating element over time.
• Perform a full descale every 3 to 6 months depending on your water hardness to prevent the copper element from overheating and triggering a premature thermal fuse blow.
• Always ensure the machine is completely off and cooled down before introducing cold water after a brew cycle to prevent stress fractures in the internal components.