The Crane demineralization filter removes salts present in tap water, leaving behind demineralized, pure water. It operates on the principle of reverse osmosis. Water is forced through a very fine osmotic membrane that retains all impurities larger than 0.0001 micrometers. This is fine enough to filter out bacteria, viruses, pesticides, lime, and salts. Demineralized water is ideal for baby food, such as baby milk or baby puree. It can also be used for drinking water, coffee, juices, or facial and hair care. Babies, in particular, require a clean environment due to their young age and weak immune systems. Sterile, pure water is crucial in this regard. Babies have very small kidneys and therefore find it difficult to filter out foreign substances. Any potential contaminants must be filtered out before they consume food.