To move rainwater further away from a foundation than the standard 2~3 foot above-ground downspout extensions, what are the underground options?
Example of standard downspout extension:
(Photo from carlsonexteriors.com)
When searching online, I see many examples of a downspout connecting to several yards/meters of flexible underground pipe which then raises to a "pop-up drain emitter". They open to allow water out, and close when the inside pressure drops, blocking water from entering from above.
Example of a pop-up drain emitter:
(Photo from kisseutopia.club)
Are these pop-up emitters necessary? Couldn't the underground pipe just have an open end with a grate?
I find the pop up emitters to be rather unsightly, especially next to a public sidewalk (which would be the maximum distance away from the foundation).
Best Answer
Pop up emitters are a good thing that do a few jobs. They stop debris from falling back down into the pipe, but more importantly (in my area) they stop mosquitos from getting in and multiplying in the standing water. If a grate was in place, you have open access to standing water.
They don't have a water-tight seal so they do not really stop water from back-flowing. It's more for debris and to some it's a little "cleaner" looking than an open grate.