The major components of a rainwater harvesting system are as follows:
 Collection system: Roof surface and gutters to capture the rainwater and send it to the storage system
 Inlet filter: Screen filter to catch large debris
 First flush diverter: Diverter that removes debris not captured by the inlet filter from the initial stream of rainwater
 Storage tank: Storage tanks composed of food-grade polyester resin material which is green in color and helps to reduce bacterial growth
 Overflow: Drainage spout that allows for overflow if the storage tank gets full
 Controls: Control system that monitors water level and filtration system
 Treatment system: Filtration and disinfection system that treats the water to non-potable or potable standards
 Pump: Pump to move water through the system to where it will be used
 Backflow prevention: Backflow preventer to ensure that under negative pressure water cannot flow backwards through the system into the make-up water system
 Flow meter: Flow meter (with data logger) to measure water production