At the start of the study, you will be given 5-gallon bottles of water and a dispenser to use throughout the study. A member of the study staff will call you monthly to see if you need more water. If you need more water and member of the study staff will visit your house and replace empty water bottles. Every 3 months, a member of the study staff will check in with you and your child to see how you're doing. Once a year, a registered dental hygienist will visit your child for a dental screening. At the same visit, fingernail clippings from your child will be collected. When your child turns 4, a dentist will conduct an exam to measure the amount of tooth decay.