What should the grate of the main drain's area be compared to the area of the discharge pipe?

In the context of drainage systems, the grate area of a main drain should ideally be at least four times greater than the area of the discharge pipe. This ratio is crucial for ensuring proper water flow and preventing backups or overflow in the drainage system.

A larger grate area allows for more efficient drainage by providing ample capacity for water to enter the system quickly, especially during heavy rainfall or when large volumes of water need to be diverted. If the grate area is smaller than recommended, it can lead to clogging, increased water levels, and potential flooding.

This standard is especially applicable in systems designed for stormwater management, where rapid collection and conveyance of water are critical for maintaining infrastructure integrity and public safety. The fourfold ratio is a widely accepted engineering practice derived from hydrological principles to ensure the drainage system operates effectively under various conditions.