An apparatus and a method are provided for a mobile reservoir system to provide potable water to desired destinations. The mobile reservoir system includes a waterborne vessel that includes a cargo hold. A collection unit comprised of a material for safe and sterile storage of potable water is disposed in the cargo hold. One or more collectors channel rainwater into the collection unit. Each collector is a sheet of a non-porous material supported on a retractable frame and a plurality of support arms. The sheet provides a surface area for collecting rainwater. A porous material covers the collection unit and operates as a filter for collected rainwater. A retractable cover may be extended over the cargo hold to provide protection to the collected rainwater in the collection unit. A filtration system is configured to offload the rainwater as potable water.