Leak deep underground, your basic pool nightmare


Jul 22, 2020
Front Range, Colorado
Hi guys,

I'm new to this forum and having a terrible week pool wise. I'm hoping to get ideas and directions for how to DIY a repair as the local pool industry here is not very deep and is very busy.

I've got a shotcrete (smooth concrete) pool with a gunnite surround. It's about 40 years old and I've owned it for 10 years. It's not easy to maintain for a lot of reasons: difficult to cover, most plumbing runs tied together underground, aging equipment, no documentation, only 1 skimmer, etc.

But I got it up and running this season with a full drain and fill (uff) including some mild hydraulic cement patching and some power line repair. I was working on getting my clarity improved and thinking about things like a new robot when suddenly last Friday I started losing water. Now, 5 days later, I've lost 60" of water with the pump off after the first 6" of water loss. It may have slowed but I'm not convinced it's stopped yet. I'm 95% sure it's not a shell leak (too fast, too sudden, nothing looks like it could leak like that, I inspected it this year) so I'm going to proceed assuming it's a plumbing leak.

At this point, only the floor (main) return and floor suction ('main drain') are still under water (i.e. it kept losing water after the lights, return, skimmer, and vacuum port went high and dry).

Unfortunately, my skimmer and vacuum port run from near the surface down nearly 10' to tee into the main. I don't know if the wall returns do the same thing but it seems likely.

I have a little $40 wifi camera endoscope that won't turn corners mostly but is worth the $40 to inspect straight pipes. I used it to inspect the skimmer pipe to a 90 degree fitting probably right before it tees into the main drain (~10' underground, below the current water level) and everything looked ok. The vaccum port attaches to the bottom of the skimmer basket so it's not implicated. I'll try my little camera in floor return and suction if they become dry/mostly dry but there is still too much water to try that (the endoscope is waterproof, the little control box on the end isn't). Unfortunately, I can't camera the returns from the pump area because they make 90 degree tight elbow turns that the camera won't go around so I'll have to do some gunnite surround breaking and digging to get to the straighter section of the pipe (ie that's on the 'next' up list). [Dear installers: please think about using 45 degree fittings with a straight section between it so homeowners can camera their lines. Or sweep 90s.]

Now, to add to mysteries:
I had a handyman with good plumbing skills out recently for another project and asked him to repair an above ground break in the return for the returns (one common line). I think he may have wrenched on the return pipe to get thing lined up (dumb) as he said he though the return line had rotational freedom going into the ground. He said it felt like a threaded fitting that was loose (unlikely). If the break was 2' underground, I would probably blame him. But: a. there is this dogleg in the return line from the pump to where the big vertical drop is. Unless digging reveals that dogleg is very short (possible), I can't believe he could break the line 5' down even if he was trying. b. We didn't see a leak develop for a week after that work. (you'd think it would have begun immediately). c. we lost a piece of pvc underground (presumably tree roots) that contains the pump power and had to run a safe but temporary (fully conduited) above ground pvc run across the broken section to get the pump on this year. (Rebury planned for next spring) So I know underground damage, probably due to trees, is currently possible.

So I've got a leak at least 60" underground in the floor lines (which TBD). The local pool company doesn't perform underground repairs and the leak company didn't know anyone who did. This is how the labor market is in my area unfortunately. It's really bad in the general market and it's only worse in the pool labor market.

So I'm looking for ideas on how to identify the exact repair needed and how to perform that repair.

I'm currently planning on hand excavating to 48" (but hopefully less) in order to locate vertical pipe runs to put a camera down and to separate both the vacuum port and skimmer from the floor suction. I've dug in my soil to 48" before and it is very safe (lots of aggregate). Unfortunately, the equipment and plumbing is not located where an excavator machine could get access (smh). I will also separate the wall returns from the floor return if the opportunity arises. So hopefully, I end up with individual return runs to the surface and individual suction runs to the surface with glued caps where pipes were made non-common. All of that will make future maintenance easier but I doubt it will eliminate my massive leak.

After that, hopefully, I'll know whether the floor return or floor suction is the culprit. I'll call a camera or leak detection company if I can't identify.

But, I don't have a grand plan for how I get the main return or suction leak fixed once I find the deeper than 4' leak.

Seems like my choices are:
- disable the floor culprit (probably means adding either more skimmers or more wall return?) via a plug etc and disconnecting from other plumbing
- try one of those water distributed epoxy repair kits or hire someone who does that work (I'm not too optimistic on that option unless I get a good camera look at a hairline crack)
- go through the shell if it is under or at the edge of the pool (I bet it isn't so I won't try this without photo evidence)
- hire pro company to hand dig 10' (who??) (If I do this, do I have them install some kind of permanent access manhole thing??) (seems like a $5k-$15k solution)
- relocate the plumbing and pump to the other side of the pool so I can use an excavator (seems like a very expensive choice and still requires all the digging if I'm still going to have floor returns etc)

Should I sleeve the lines in larger pipes before reinstalling?

Should I upgrade 1.5" pipes that I find to 2"?

Should I use long sweeps instead of vent elbows to allow camera work?

Should I use schedule 80?

(Seems like yes, yes, yes, yes).

Anybody have other ideas? Suggestions? Stories? Pour a glass of scotch in your pool for mine?

I'm all ears.


Jul 22, 2020
Front Range, Colorado
I'm not aware that I have a hydrostatic relief valve. Once it drains out entirely, which I think will happen, I'll take another look and maybe put up some photos.

Edit: Are they sometimes part of the drain assembly (i.e. could it be under the floor suction grill?)
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Jul 22, 2020
Front Range, Colorado
Hi guys,

Thanks for the info. The pool ended up draining itself to ~0.5' of water and I was able to use my cheapo amazon endoscope. I popped the drain cover; no extra fittings under there. I got about an 8' view of the main suction pipe and things seemed pretty ok (it's hard to get a great view of all sides of the pipe).

I also tried to camera the other fitting which I have always assumed was a floor return. However, I'm wondering if its a hydrostatic relief valve (or was, as it doesn't seem like there is anything valve like in it). It was a brass NPT fitting set in correct and then a three holed brass cage above it. I've attached a not so great photo of the fitting looking down on it. Also, this link looks a lot like it without the top piece which I haven't tripped over lying around (but will have another scan of the deep end now that the pool is emptyish). In terms of mysteries, I don't think it's ever had the top piece and I'm not aware of anything that has happened to the water table (besides the usual summer) that would cause some big change.

I put the camera down it and only got about 8"-12". It seemed like there was a short section of pvc that abruptly ended without a tee or 90. It's common to struggle to get around a tee or 90 with this cheap endoscope but I can usually can make it around the first corner. However, this pipe seemed to dead-end in some rocks (my soil below a few feet is pretty rocky). I didn't see anything that would, to my amateur eye, be a valve or seal or anything else. It just seems like an open pipe into the base of the shotcrete or into the earth.

I tried removing the top brass 3 hole fitting grill with an 18" channel lock but that was hopeless. I've ordered and received ($$$ for 1 socket) a deep 1/2" drive 2" impact socket and am planning to try that with a dewalt battery powered medium torque impact wrench under the assumption that removal of that grill will be part of any replacement. Hopefully I don't break the pvc or brass embedded in the concrete.



Rich D

Bronze Supporter
Aug 3, 2018
I would get all the water drained out before you try to get it out. Then you should be able to see inside to be sure that is what you think it is and be able to see what you are doing. The problem with the industrial size socket you mentioned is they are almost all tapered at the very bottom so you will need to chip out the plaster and maybe into the gunnite so your socket engages the nut correctly or grind down the socket to remove the taper. I would proceed very cautiously and be sure you know what you are trying to remove before doing so.


Jul 22, 2020
Front Range, Colorado
Hi guys and gals,

Thanks for all the replies.

Details in case the magic of the internet leads someone to find this and need help tackling their own:
I ordered a 1/2" drive 2" deep impact socket ($$) from Amazon and a set of impact extensions

Note: it's possible this (and thus perhaps yours) brass hydrostatic relief valve actually takes a 1 7/8" or 1 15/16" socket; I don't have a set to check. The 2" worked.

Regarding socket clearance to pool shell: I imagine everyone's pool plumbing will be different but my hydrostatic relief valve body was not cranked tight to the shotcrete shell so I had no trouble getting the deep socket on. I could believe that if someone had screwed the valve body all the way in, it might have been trouble getting the socket seated well. If you have any space between the shell and the bottom of the hex fitting on the valve body, you'll probably be ok.

First, I borrowed an older impact wrench that only produces 170 ft-lbs. No dice. Next I borrowed a Dewalt DCF899, which produces 700/1200 ft-lbs (fasten/breakaway). I wasn't 100% sure it was going to work (no signs of movement initially) but within 30 seconds it was off. Great tool. Don't forget the ear pro (oops). HD also sells a similar price point Milwaukee with 1000/1200 ft-lbs if anyone has to buy their own.

The brass fitting came out looking great, which is kind of remarkable given my water quality isn't great and I assume this fitting has been there 40 years. Therefore, I assume I'll have no trouble reusing the pipe to install another hydrostatic relief valve.

I did not put my camera down the hole again but I did drop a broomstick handle in. I can tell, in comparison to the neighboring pvc main drain, that this hole terminates in loose material (cobble) and is not a piped fitting. So I think, minus getting it all running again and having water be discharged from the fitting with the pump on, I have to assume I've been wrong for a long time and this is long-broken hydrostatic relief valve and not a floor return. (the pool and house did not come with instructions so to speak and this is my first pool... not a good starter pool!).

It appears the direct replacement might be this part

Or in plastic?

Price of the part doesn't particularly matter to me too much since I'm saving the labor charge. Opinoins?

Barring feedback here, my plan is:
- buy the brass part
- install it with perhaps 15-25 ft-lbs (unless it comes with a spec)
- Fill pool with ~5000 gallons (a portion of the deep end)
- Plug skimmer and vacuum ports
- Run pump briefly to see if the hydrostatic relief valve is forced open etc.
- Fill pool

Now, I have another question (since I have the pool empty) but I'll ask elsewhere and link here...
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TFP Expert
Bronze Supporter
In The Industry
Aug 10, 2017
Morris Cnty NJ
The drain wont open without water pressure from under the shell. Use a brass hydro plug and use tape on threads doeant need to be super tight just snug. Install by hand with wrench no guns on them