Our water also contains a lot of calcium. The cleaning program is probably executed every two months or so. I'm assuming that the dishwasher can sense if the p

Our water also contains a lot of calcium. The cleaning program is probably executed every two months or so. I'm assuming that the dishwasher can sense if the pumps it contains use more energy to pump water (I know pumps that can give the user this info but I think this is an estimate based on some magic numbers from the designers of the motor control software). It might be also a simple timer. :)