Drinking water with crem in it can cause sickness. Such water must be allowed to sit for a day before the crem within it settles to the bottom and the drinkable portion of water is poured off the top.
Not unlike clay, crem is moldable and commonly used to make pottery, or fill small holes in grain polyps. In the distant past and among more "primitive" communities, it was used in building construction with stone or for creation of crem bricks. If left alone, crem eventually hardens into stone. Buildings would grow stalactites, formed by stormwater slowly dripping from their eaves, which had to be cleaned regularly or they weighed down the buildings' roofs so much that they collapsed.
Crem has been used as a derogatory term by several characters in The Stormlight Archive, likely referring to the notion that crem is stormleavings.