Point-of-use (POU) systems are installed under the sink and clean and filter only the water at that faucet. They are generally installed at the kitchen sink and in the primary bathrooms where teeth are brushed. These units are smaller and considerably less expensive. It is a good option when taste and harmful contaminants are the primary concern and the water needs to be purified for drinking and cooking. These units do not protect your showers, toilets and other appliances from staining and mineral deposits.