Limescale causes faults and impairs flavour. When water is heated, limescale is deposited. Pipes narrowed by limescale not only slow down the heating process and therefore consume more energy, but may even cause the machine to break down completely. Limescale also has a negative effect on the coffee itself. Although a small amount of calcium carbonate is important to the flavour of coffee, too much gives the water an unpleasant aftertaste and prevents the coffee aromas from developing as they should, partly due to fluctuating water temperatures.