In recent years the planning of water services has been greatly assisted by the spread of market surveys of potential users. These surveys aim to uncover users’ preferences for the proposed service, and what they would be willing to pay for it (hence the name, willingness-to-pay, or WTP surveys). These surveys provide a variety of information about householders’ current sources of water; the volume of water used for different purposes; their preferences about the proposed service; what they are now paying for water, and what they would be prepared to pay for a specified improvement; and whether they would connect up to a new supply source. These surveys are equally applicable for sanitation and sewerage. (For a fuller description see Chapter 13).