PVC liner leak. I have some ideas, but would appreciate repair suggestions


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I recently converted a 10x10 fallow courtyard planter box into an excavated fountain pond by digging out the space to a shallow depth of 12". I then poured a reinforced concrete footing about 36" square and 5-1/2" deep (inside an inlaid 2"x6" wood form) in the center of the dig to support the fountain, and then overlaid a 45 mil PVC liner over the whole excavation. Unfortunately I had to glue two sheets together using an edge-to-edge seam with a 4" wide PVC strip overlapping the joint. I used a commercial PVC glue designed for shower pan liners. I did the gluing in my back yard because of the sheets' size and therefore had a difficult time controlling the preciseness of the bond, but it seemed OK at the time and there you have it.

In retrospect I probably should have laid down a felt liner substrate underneath the PVC liner, but the pit bottom was almost pure sand and I figured any small rocks or sharp objects would simply be pushed down into the sand and not be a puncture problem.

I then laid a 16"x16"x4" solid concrete block over the center of the liner-covered footing, cushioned by two thicknesses of PVC sheeting to protect the liner from the block's sharp edges. The fountain was then constructed piecemeal over the block, consisting in six 8"x8"x8" open-core concrete half blocks and four interspersed 8"x16"x4" open-core half blocks stacked and mortared on top of each other, forming a hollow block tower some 5-1/2 feet tall with 8"x8" "ledges" spiraling around the outside. The center of the column was plumbed for four copper tube spitters emanating from each face of the uppermost block, creating a fountain with four streams of water falling from the tubes and splashing on tile ledges of sequentially increasing heights before dripping down to the surface of the pond (see photos).

After completing and testing the plumbing with a Pond Guy pump and non-pressurized filter intake, I filled the pond and admired my handiwork. Everything was working and looking great for maybe three days - and suddenly, yesterday, the morning of the fourth day, the pond level dropped several inches. Oops.

I decided to wait and watch to see how far the water level would fall. I presumed that wherever the level stabilized, the leak would be somewhere around the liner's perimeter at that level. I am also presuming that the leak would most likely be somewhere along the glued seam. At this point, a day after the leak began, the water level has dropped all the way down to the bottom of the 16x16 fountain base block but is still covering the liner over the concrete footing (photos).

So: Suggestions? In the absence of a better idea, I am going to 1) mark with grease pencil on the PVC around the perimeter where the water level comes to rest 2) drain remaining water and dry entire liner surface 3) let stand for a week or so for water that has leaked under the liner to dissipate into the sand 4) use a thick roller-paintable PVC-compatible sealant product such as Flex Seal over the entire seam as well as the area of liner within and just beyond the marked perimeter, and 5) refill and hope for the best.

I originally purchased about 800 sq ft of this liner ten years ago in hopes of building a pond up in northern Michigan where I used to live. I kept it in storage all these years. When I moved to Florida in February nearly three years ago I decided to bring it with me. The 8x12' sheets were folded into eighths and the cold weather made them stiff as boards. However, once I got them outside in Florida, they became quite pliable and in fact were downright floppy in the 80 degree sun so it was easy to glue, stretch and place them. One thing I did not consider, however, was that once the liner was in place and the pond filled, the weight of the water compacted the sand under it and I noticed there was an edge formed between the sand and the boards enclosing the poured concrete fountain footing - where it was once flush, there was now a 2-4 mm drop from the board edge to the sand - that the liner would've had to stretch to accommodate. In hot weather this would not have been a problem, as warm PVC is quite stretchable. But the water temp was only about 60 degrees, which would have made the liner much less conformable to stretching that amount, and hence more vulnerable to tears. Again, though I don't think this is where my leak is, I probably should have used the recommended felt underlayment.
 

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You can get a 10x10 liner in one piece. If it was me. As much as I hate to say. I would rip it out and get a 1 piece liner.
Just they way you described putting that seam together and how you struggled with it. I would not trust it. And if the liner is stretched that is not good. It should be nice and loose. When you install a liner. You start in the bottom. So when you lay the liner in place your not pulling or stretching it. you then fill the pond with water to help it settle before putting it permanently in place.
I think I filled my pond and drained it 3 times before doing any rock or edging to make sure it would not get stretched or pulled when placing rock.
I hate to here things like this you put so much work in it. It’s not worth cutting corners and putting Band-Aids on things. Fix it once if it right.
you just built it and are already having problems with the liner. Not worth possibly having to deal with for the rest of the ponds existence.
And I think most would suggest some kind of underlay. Not to mention pvc liner is not as forgiving when it comes to punctures and tears

when I did my pod a few months ago. I found a firestone 45mil epdm liner 20x25. Seamed in the middle by the factory.

I’m sorry your having such issues

loose kinda like this.

0175F7B5-48E0-4D17-B209-5D15F86CD57D.jpeg
 
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Jhn

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PVC liners are cheap for a reason they degrade quickly and tear easy. I would redo it, using a 45 mil epdm liner, placing underlay under the line. Then cutting another piece of underlay to put between the fountain base and the liner. Also watch the edges of the poured concrete and fountain base, if you didn’t grind the edges they could easily cut the liner as it pulled tight.
As joe joe suggested lay the liner loose and work the folds out as you fill it so it doesn’t pull tight on you.
 
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You can always use the pvc liner as the underlay. Maybe this will help.
im a little ocd. So I did this like 3 times to make sure the liner was settled. Then when placing my rock I started low and worked my way up. With nothing holding the liner around the edging (coping).
so this way the liner will get pulled into place instead of being stretched. You need to make sure you have plenty of extra liner.
I believe you said when you placed the structure in the middle it pulled the liner and stretched it. Which is exactly what I’m talking about.

I hope this helps.

 
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Mmathis

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I would switch to an EPDM liner. My pond was EPDM, which was great (new house, and still waiting to build new pond is the reason I’m speaking in past tense). Then I decided to add a small external bog, and yes, PVC was cheap, so bought a sheet. But as I was walking around on it and arranging my tubing system, I wasn’t happy that the PVC seemed so much more....fragile than the EPDM and had very little “give.” Before I put any more work into the bog, I ripped out the PVC liner and bought another smaller piece of EPDM. I never regretted that choice!

Remember that the liner is your foundation, and your pond will only be as good as your foundation.

Also, if I was going to place anything heavy (like a concrete block or a heavy rock), I would cut out a separate, small piece of the liner to fit, and lay it down on top of the liner, under the heavy object....like a coaster to protect the finish on a nice table.
 
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@Michael from Daytona - I can't share more than what has already been said, except to encourage you to take the good advice you've been given. The first thing that goes into the pond should be the last thing you try to save money on, in my opinion. I know you put a lot of work into seaming that PVC, but I'd just chalk it up to experience and get yourself a single piece of EPDM.
 
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I also, as Lisak1 has said, highly suggest you take the advice of switching to EPDM.
I can tell you this from experience with PVC liners...bad experience.
I, like you, wasn't experienced enough to know better and hadn't found this forum until after the fact.
In my early days of ponding, I used pvc. I also seemed two pieces together. During the dead of winter the seam split. A one piece pvc liner was installed in the spring. A branch punctured that one with ease. When that liner was removed, it was brittle from the sun. Both those liners were only months old. One only 3 months.
PVC liners are crap and should not be sold for use in fish ponds...period.
EPDM with it's geotextile liner is the way to go. The liner is the most basic component of the pond and should be robust enough so that you don't have to tear all your hard work apart to replace it prematurely.
Good luck.
Oh, I applaud you for your design and ambition. Your pond looks fantastic!
 
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If the seams i can see are the welded seems there should be no voids or air space between the folds. Like others recommended start with a clean slate yes it hurts now but don't look at it as you did wrong look at it as you found one way to avoid doing it again. Yes a one piece is your best bet . but what i didn't see anyone mention and from what i see in the photo is the liner looks tight / stretched. you want to avoid this so much so you want to have a fold where you can have the liner so if something was to settle shift shrink for what ever the reason there is spare. Leaving the existing in place to help prevent puncturing can work but i would still apply a non woven 4 or 6 oz underlayment . there is never too much protection . but you will want to make sure your first liner does not hold water puncture it here and there or you could end up with a big bubble between liners.
 

sissy

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for that you can get rubber roofing .I know here they sell it at builders discount center really cheap .I bought a liner there 10x15 for 23 dollars plus tax .It is on a giant roll and they cut it to my size .I just bought it yesterday to replace the liner in my lily pond for spring of next year .I had to go to Danville yesterday so figured since I was there I would get it since I needed screws any way .
 
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for that you can get rubber roofing .I know here they sell it at builders discount center really cheap .I bought a liner there 10x15 for 23 dollars plus tax .It is on a giant roll and they cut it to my size .I just bought it yesterday to replace the liner in my lily pond for spring of next year .I had to go to Danville yesterday so figured since I was there I would get it since I needed screws any way .
You bought a 10x15 piece of rubber roofing material for only $23! That's way cheap! Isn't that stuff EPDM?
 
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sissy

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yes it is and only difference Goodyear told me is what they use to keep it from sticking to it's self is the powder .For fish liner they use baking soda .You just have to make sure you clean it really good with a hose .epdm is epdm no matter roofing or pond liner ,they just make more money off pondliner .We have a Goodyear plant here in Danville VA .Funny to say but they had a sale on the liner at BDC so I could have gotten it for 16 dollars plus tax .OH WELL . ;)
 
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So I read all your suggestions and did some research. After watching YouTube videos on the various pond liner materials, it seemed to me that reinforced polyethylene (RPE) is a better choice for my application than the EPDM everyone seems to favor. It's not any more expensive than EPDM (at least not from this company) and it's significantly tougher than either PVC or EPDM because it has reinforcing strands woven within it, making it difficult to puncture even at half the thickness of the others. Furthermore, at 30 mils it's also almost half the weight of the other two. So I located a sales outlet at Aquatic Biologists in Wisconsin and spoke to a rep who seemed to really know his stuff. He suggested leaving the leaky PVC liner in place and laying the RPE directly on top of it. I told him I did not want to take my fountain down, as it is in several pieces, so that would require cutting a square hole in the center of the new one-piece RPE liner two inches per side smaller than the 2" x 24" x 24" concrete fountain block footing - and passing it down over the fountain. This would leave 1" selvage on each side of the footing, which would provide a "lip" all the way around on which to attach four 1/4" x 1" x 24" stainless steel straps to fasten the RPE to the footing. Over this would be placed seam tape (which the company supplies), providing a waterproof seal. One other thing I had not thought of before was sealing the concrete fountain itself with a liquid sealer, including the footing, as water will seep slowly through unsealed concrete, and the bottom 12" of the fountain will be under water.

After the layment was down, the rep suggested I apply a "geotextile" liner on top of the whole thing to protect it from the sun, a liner which his company also provides. I am going to lay 1/4" ceramic paver tile on top of the geotextile around the fountain base and out to where the flat bottom begins to slope upwards. This is where the rep suggested I lay a single-row perimeter of 6-8" rounded river rocks, to provide a non-sliding backstop for pea gravel or whatever else I want to use to cover the remaining liner right up the slope to the edge of the pond. I can also use the river rocks as a footing for plant shelf legs in order to level the inner edges of plant shelves.

The whole thing cost under $140. I can't wait for the materials to arrive!
 

sissy

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Why would the liner need to be protected from degrading if it so strong .Epdm only needs protected when exposed to sun and even then has not degraded for me after being left exposed .I bought and epdm liner for a lot less and even roof liner is much cheaper.I just got a piece yesterday from builders discount center and for the 12x20 liner was only 49 dollars .
 

addy1

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it seemed to me that reinforced polyethylene (RPE) is a better choice for my application than the EPDM
I used a liner from bend tarp and liner in Oregon. They also have RPE, check them out, a great company to work with. At the time I bought it was called ppl. It survives anything. Including sun exposure. Deer have walked on it, rocks have fallen on it, zero issues. Even drove my tractor on it when we using it to bucket in the pea gravel for my bog.

I did not put any cover over the liner.

I love the stuff. It also does not get as slick as epdm, easy to walk on in the pond.
 
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I used a liner from bend tarp and liner in Oregon. They also have RPE, check them out, a great company to work with. At the time I bought it was called ppl. It survives anything. Including sun exposure. Deer have walked on it, rocks have fallen on it, zero issues. Even drove my tractor on it when we using it to bucket in the pea gravel for my bog.

I did not put any cover over the liner.

I love the stuff. It also does not get as slick as epdm, easy to walk on in the pond.
can it be bent to a 90 Degree angle what i am asking is i want to wrap a 12x12 block of aquablocks and seal the top so i have the block sealed on 5 sides leaving the one side open
 
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addy1

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can it be bent to a 90 Degree angle what i am asking is i want to wrap a 12x12 block of aquablocks and seal the top so i have the block sealed on 5 sides leaving the one side open
yes I bent mine around the skimmer edge and over the bog/pond edge. Not the best picture, wind is howling, it is 25 out there, but you can see the liner come up and out of the pond over the 2x5 landscape timber than down into the bog. Two 90 degree angles. Deer have walked on that edge it still is hanging tough. They like to nibble on the lilies in the pond and stand there to get them. The rocks I set on the edge are all knocked off right now because of the deer. I have a lot of fix up after winter due to deer.
Capture.JPG
 
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THANKS ADDY
is there a way to glue it / seal it together ?
 
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addy1

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You can with tape they can send with it. I used tape for one place and my fav pl roofing goop then tape over the edges, still not leaking.

It comes in any size you ask for.
 
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