The AalborgPortland cement factory gets the material for their cement from this huge chalk/calcium deposit. The water in Aalborg is extremely hard and it is full of chalk. Danes are used to regularly using de-chalkers to clean their coffee machines and washing machines, etc. A build up of chalk collects on everything that the water touches. It is a pain in the ass to clean and you can taste it when you drink the water, too. It took me a long time to get used to the taste, but now, I am sure my bones will be much stronger because of it!