After it permeates, then what? The water still has to go somewhere, and usually it's into nearby ditches (and then streams, and then rivers). As well, with any

After it permeates, then what? The water still has to go somewhere, and usually it's into nearby ditches (and then streams, and then rivers). As well, with any larger rainfall the local water table below the grass will fill up quickly- now the water is running on the surface. Permeation is definitely good, but having more stops before it gets there is important to prevent floods. (To be clear, I'm not expert on this at all. But I did marry one, and you sort of absorb a lot just from conversations over dinner).