That’s where I’d start. Also keep in mind the the drop differential that makes it work is the difference between the intake end in the pond and the outlet end elevation, not the distance from the top of dam.

If you aren’t going to use a check valve, just make sure your hose is filling the pipe on the backside and not flowing into the pond. As said above, raise the pond side 45 at least 4” higher than the backside 45.

add 10’, lather, rinse, repeat.

No, it's got the small breather pipe on it that causes it to siphon only when the lake gets high enough. The breather pipe is a 2" pipe that ordinarily has the end out of the water. When the lake rises, it seals it off and starts the siphon, which moves much more water than a drain pipe.

The 8" pipe does function as a regular drain pipe until the lake gets high enough to cover the breather.

I think a system like this is the only long term solution. The pond owner might as well go ahead and install it correctly or it will always be a headache. I can't imagine a pond being built without a spillway either.

I would also say that the PVC siphon system is much superior to the old method of a a metal drain at the bottom of the pond with a standpipe in the front. They will eventually rust out and it's a big job to replace.

Ah I understand what you are talking about now.

Not a pond owner so, this is interesting, my question, how does the 8” line act like a drain and then when the breather is blocked act like a siphon, seems as though it would draining before it started siphoning, just having a hard understanding

One thought that comes to my mind. On my pond drain it has a slightly larger PVC pipe over the drain pipe that allows water to enter the drain pipe at the bottom of the larger pipe which is under water maybe 10 inches and the larger pvc pipe also has a mesh cover to prevent debris from clogging the top of the pipe. This allows the water to drain clog free. When the pond is full you will see a strong swirl in the water that collects alot of debris which would quickly clog the pipe if this "filter" were not in place.

I would think the siphon pipe would also need some type of protection from clogging to keep your drain working. I am sure there are folks who know how to achieve this easily on here.

This is getting complicated. Ive done this manyl times. Just get a. gas gransfer pump on the end and suck water through the pipe. When water starts fliwing out remove the pump hose and the siphon will do the rest. 5 minutes and done. You just need to prime the line which is also very easy.

Ive drained 2 ponds this way and dozens of pools. If you dont have a fransfer pump they rent them for super cheap at home depo or lowes or other rental companies.

easy peasy.

That way will work. Just like siphoning gas.

I have done a poor job of explaining it. I will make a picture next time I am there and bump this thread back up.

So we did this with several ponds that had metal stand pipes that rusted out and would drain the pond if nothing was done. First step was to get enough concrete into the old pipe to seal it, and that's not as easy as it would seem.

Next, dig a trench through the pond dam until it gets to the normal water level. Obviously, that's easiest when the pond level is lower than normal. Get the trench level and lay the 8" pipe in it. It needs to be level across the dam. Put a 45 degree joint on the back side and let it go all the way to the bottom of the dam. You need some way to plug the end whenever you are gonna drain it.

Put another 45 on the front and extend the 8" pipe as far down that side of the dam as you can to get it deep enough to drain all of the pond. At that joint, it needs an access to put in the water to siphon it if you want to drain the lake. There also needs to be a 2" breather pipe installed here. It goes up a foot or so, then has a 90 degree elbow and the next joint extends out over the water. Then there is another 90 and the next joint goes down. It needs to stop just above the top level of the 8" pipe. That's all that's needed.


Normally, water just flows through the 8" and the bottom of the breather pipe is in the air. When there is a big rain, the lake rises and fills the 8", and the water then covers the end of the breather. Once that happens, it begins to siphon and moves way more water than it normally does. Of course, you still need a spillway somewhere on the pond that is maybe a foot higher than the top of the 8". The pond should be designed so that water runs out the spillway only in a real flood. My pond runs across the spillway every 5 years or so. It will siphon maybe a dozen times a year.

One problem is that when water is running through the 8" pipe but the breather is not in the water, the beavers can hear that water running and they pile mud around the breather. It isn't all that strong, so they sometimes break it. I've had to repair the breather a couple of times in past 20 years.

Why not a Concrete Spillway in th' Corner of th' Dam??

You need a check valve on the pond side. Prime the pipe by filling completely and then release and the lowest point downhill.

That video I posted in the other thread spells it out.

Here's the pics I said I would post. You can see that the water level is above the bottom of the breather pipe and it is siphoning water after all the rain on Tuesday.



And this is what it looks like when the siphon is working. I don't know how much the siphon increases the flow rate, but I would guess at least 3 times as much.