Question about adding a stream

[Ember]

I have a long narrow wildlife pond, very shallow at one end with a deep bit at the other where a pump feeds a very small waterfall. I would really like to add a stream winding down a slight slope towards my larger fish pond (it won't join). My problem is I don't know how to join the stream. I don't have much overlap on the pond liner, about 6 inches and it's not EPDM so I can't stick it. I think it's PVC. Can I just overlap a new piece of liner into the existing pond? If so should I put in in the water over the existing liner or under it? My head tells me that if it goes straight into a drop the water shouldn't wick back but after reading some posts I may well be wrong so any advice would be most welcome.
I don't really want to buy a new liner just to add a small stream as the pond has a lot of frogs, newts etc and I don't really want to disturb them plus it would be expensive.

 

[dinm]

I have a long narrow wildlife pond, very shallow at one end with a deep bit at the other where a pump feeds a very small waterfall. I would really like to add a stream winding down a slight slope towards my larger fish pond (it won't join). My problem is I don't know how to join the stream. I don't have much overlap on the pond liner, about 6 inches and it's not EPDM so I can't stick it. I think it's PVC. Can I just overlap a new piece of liner into the existing pond? If so should I put in in the water over the existing liner or under it? My head tells me that if it goes straight into a drop the water shouldn't wick back but after reading some posts I may well be wrong so any advice would be most welcome.
I don't really want to buy a new liner just to add a small stream as the pond has a lot of frogs, newts etc and I don't really want to disturb them plus it would be expensive.

Been wondering the same, had the same idea in July, and absolutely failed. Every single time there was a leak due to capillary action, my mind was telling me it must be the stream but it wasn't it was indeed capillary action, I figured the overlap I didn't do properly since I had it overlapped on gravel in the pond, didn't have enough height overlap and would require me to remove gravel from that area where the stream comes in, did not want to do that since there's a decent amount of gravel.

I'd watched a video back then where they overlap streams and the liner goes in then a big rock to prevent water going under it, but I'm interested to see what people here have done. It seems simple, but I failed terribly at it.

I don't know about your situation, but my goal was to do that as well, and I always had wicking, constant wet feet near where it connects, intuition told me that too, that if I just did it like that, it'd work. That video made me think it probably needs to look like this to not wick water out, but I've only failed so someone that knows better will uncover the mystery
.

 

[Ember]

Been wondering the same, had the same idea in July, and absolutely failed. Every single time there was a leak due to capillary action, my mind was telling me it must be the stream but it wasn't it was indeed capillary action, I figured the overlap I didn't do properly since I had it overlapped on gravel in the pond, didn't have enough height overlap and would require me to remove gravel from that area where the stream comes in, did not want to do that since there's a decent amount of gravel.

I'd watched a video back then where they overlap streams and the liner goes in then a big rock to prevent water going under it, but I'm interested to see what people here have done. It seems simple, but I failed terribly at it.

I don't know about your situation, but my goal was to do that as well, and I always had wicking, constant wet feet near where it connects, intuition told me that too, that if I just did it like that, it'd work. That video made me think it probably needs to look like this to not wick water out, but I've only failed so someone that knows better will uncover the mystery
.View attachment 160554

I only have a little gravel in the bottom so can remove that but what do you mean by height overlap? I don't have enough pond liner to do a deep overlap like your drawing if that is what you mean.The pond is only about 6 inches deep at the point i'd like to add the stream but I could go to a deeper bit. I'm planning on making a small deep pond at the bottom of the stream to put the pump in to go back up to the pond. The bottom of the slope is about 10" below the pond.

 

[j.w]

@Ember
I have no streams, just ponds so can't help ya there

 

[csdude55]

I'm about to go through a similar thing :-O :-O I have a 1000G pond, and tomorrow I have a guy digging a 6000G pond nearby. I'll be building a stream / waterfall to connect the two.

I imagined that I would border the stream with rock, then cut a piece of liner that would go over that border to create a channel. At the top where it connects with the smaller pond, I'd put the stream liner underneath the pond liner. I figured that a buffer of about 12" of the stream liner shoved underneath the pond liner would be enough to prevent water from seeping. Gravity would keep it from flowing upward, right?

Maybe a strip of this underneath the connection?

https://www.amazon.com/Pond-Liner-Seam-Tape-Double-Sided/dp/B0BBG63Z13/

 

[Pablo]

I know there are a few people here that can help, but pictures will help them figure out if what all of you are planning with the streams will work. I just finished a small stream from a bog to a pond, but I just overlapped the bog liner over the pond liner by a couple of feet, downward slope so the water will not seep up. But what you are all describing sounds a bit different. If you have to seam the liners then there is more involved with that. Go to the Construction forum and you will see a sticky thread for seaming liner.

 

[GBBUDD]

Been wondering the same, had the same idea in July, and absolutely failed. Every single time there was a leak due to capillary action, my mind was telling me it must be the stream but it wasn't it was indeed capillary action, I figured the overlap I didn't do properly since I had it overlapped on gravel in the pond, didn't have enough height overlap and would require me to remove gravel from that area where the stream comes in, did not want to do that since there's a decent amount of gravel.

I'd watched a video back then where they overlap streams and the liner goes in then a big rock to prevent water going under it, but I'm interested to see what people here have done. It seems simple, but I failed terribly at it.

I don't know about your situation, but my goal was to do that as well, and I always had wicking, constant wet feet near where it connects, intuition told me that too, that if I just did it like that, it'd work. That video made me think it probably needs to look like this to not wick water out, but I've only failed so someone that knows better will uncover the mystery
.View attachment 160554

This diagram if the water level is filling up the drawn pond area but has what looks like a boulder in the pond. if the water level is close to the surface of the pond are then you have about an inch or 2 of over lap., the liner that comes from the stream that goes to the bottom of the pond does little as you still only have and inch or so of overlap ABOVE the water line .

so yes you would need to seam that over lap it is to small to not seam

 

[Lisak1]

The answer is in front - the liner from the top goes in front of the liner from the pond but you do need to get that pond liner up as high as you can behind it. And joining them together would be even better if you can. Hopefully you're planning to use EPDM for the stream extension.

I do worry about you going to all this trouble with a PVC liner though... you have a situation that's bound to fail eventually. Is it expensive? It's honesty one of the cheapest parts of pond building and it's the last thing you want to have to think about replacing. Just my opinion but if I were going to all that work I'd replace the whole liner and do it right from the start. The number of hours you will spend wondering and worrying "is it leaking?" will make you nuts.