I recently made my flower bed larger and even with one of those accordian flexible tubing, whenever it rains my mulch gets washed out. So I got a 4" pop up drain emitter and 10' pcv tube. I buried the tube under ground (with the proper slope) and directed it out to the middle of the lawn where the emitter is connected.

My question, since I'm using a 4" tube, what would happen if there's not enough flow from the down spout. Would the emitter not open? Would the water back up? I just have to wait until it rains to see what happens.

 

It will only open when there is enough water to push it open if it is like mine.

One minor downfall of a pop-up is that the capacity for flow is actually less than a 4" pvc pipe. I have large gutters and a large downspout and the water flow for a "gully washer" storm can be backed up a bit, but that is a minor rare occassion. - Not worth a "Y" and another pop-up.

I don't know if what I have is an "emitter", since that term indicates a slow gradual flow.

Dick

 

I think success will end up depending on how much roof/trough area you are draining. If your downspout is like most, during a heavy rain it can flow like a fire hose. I can't see the pop up providing anyway near enough capacity to handle what the PVC will carry. I have one for my pool overflow that works great but receives a much slower flow rate during rainfall than a typical downspout because of gravity. A gradual slope compared to a vertical supply feed. You may need to extend your PVC further and find a way to allow the end to stay completely open at the edge of the yard if you want it not to back up.

 

Success, it worked. We had a down pour yesterday and the emitter worked as designed. I too was also concerned about not having enough flow for the 4" dia tube. I was also concern that the 10' tube wouldn't be long enough, causing the water to flow back to the flower bed. It took a couple few minutes after the rain started before I notice the emitter was flowing water. But I didn't see it backing up out the down spout, so I figure all was well. I guess the 4" tube had to completely fill with water before the emitter will open.