With this technique, rainfall that has accumulated on the building’s roof is directed to a storage tank. Designing the storage tank must take into account the catchment’s availability, rainfall, and water consumption.

Before connecting to the storage tank, each drainpipe should have a filtering system, a first flush device, and a mesh filter at the mouth. A method for excess water overflow should be present in every tank.

The recharge system might receive more water. Water from storage tanks may be utilised for extracurricular activities like gardening and washing. The most economical method of collecting rainwater is this one.

The primary benefit of collecting and using rainwater during the rainy season is not just to conserve water from traditional sources but also to reduce energy costs associated with water distribution and transportation. If groundwater is being drawn to satisfy demand when it is raining, this also conserves groundwater.