I installed a 12" siphon the last couple days. The MU guide says to drill a hole in the outlet elbow. The purpose is so water exit out the bottom so it will not freeze.

I have not seen any other diagrams with the hole drilled in the elbow. I thought the idea of the elbow was so it would hold water.

Should I drill or not?

I will start loading pics soon of the 10 acre lake I've built over the last 2.5 months, not including time to remove tree's and brush. It's been fun and more time consuming than I expected.

Are we talking about the last elbow.....the 22.5 or 45 that goes back up? The intention of this elbow is to not let air suck back into the system in a siphon situation, if you drill a small hole and its closer to the outlet any air would go out instead of back up towards the horizontal run.

Well, I didn't drill the hole, but it would not affect the system. It wouldn't drain out the water as fast as it would be coming down to the elbo.

By the time I realized it would be OK, I had already put a 4' extension on it and covered everything except for the end.

It rained Thursday. There's about 2 acres of water in the lake. I still have dirt to move; we'll be back at it Monday.

Sounds like it might be too late now to drill it, but if you can, Stacy, definitely drill it. I know every setup is probably a little different, but when my pipe is just draining - not siphoning - there is very little airspace above the waterline inside the 45 degree elbow. If I had a 4' extension on mine, I think that elbow would be entirely full. Then if it froze, the pipe would be plugged and unable to drain at all.

That's sure something to think about, Vamaz. I've thought that I might just empty the pipe of water before it freezes hard enough to bother.

Stacy:

If the pipe is dry inside, could you get a 2"x3", tape a right angle drill to it and drill a drain hole in the elbow by putting it in from the end of the pipe? The pipe is only 4' long, and plastic is pretty easy to drill thru. I'd feel better if the elbow had a rock "catch basin" under it so the ground didn't plug the hole tho.....

I hadn't thought about taping a drill to a board; good idea Esshup. I had thought before, that if I was going to drill it I would put clean rock under it. I don't know if it would drain without the rock, but it sure is worth a try. If it doesn't drain, nothing would be lost.

I put 14 unopen bags of sakcrete on the side that would feel the pressure during a siphon event. It's rained over 3" in the last few days, so I would hate to dig it out.