Fixing a main drain leak -- or not

Jun 4, 2018
112
Houston, Texas
A couple of months ago, a friend and I replaced my pool's suction line -- the one running from the skimmer to the pump. It was leaking -- sucking air to the extent it was audible. The suction was so poor, as a result of this, that my suction-powered pool vac wouldn't run. So we replaced the run of pipe from the skimmer to the pump with no problems. Suction's great now and that little vacuum even climbs the walls as it cleans the pool.

But I've been noticing a drop in the pool level now -- as much as an inch over a period of 3 or 4 days. We're getting a lot of rain here in Houston right now, so this isn't an issue, since the rains have made up for any losses. But I need to look forward to times when we won't be getting much rain.

When we replaced the old suction line, we didn't entirely uncover the old line. Yes, we did uncover sections of it, but not all of it. And we obviously missed where the main drain at the bottom of the deep end tied into the old line. At the time I completely forgot about the deep end drain. So the result is the main drain has been disconnected from the pool suction, but it's still connected -- somewhere to the old suction line. Honestly, I don't see what this hurts -- it not being hooked up to the suction line anymore, I mean. The pool vac is taking care of anything on the floor of the pool and it's handling the flow to the pump just fine. We're getting plenty of suction throughput through just that one line. But then, there has always been one line -- but a line that previously somewhere the main drain tied into. Now that the old line leading from the main drain to the suction line is inactive, I suspect it is the source of the water loss I'm seeing now. We didn't cap that old line -- we just left it down there. So as long as the water level in the pool is greater than that old suction line, I think it will continue to be a source of leaks.

I suppose we could dig around and find out where it ties into the old line and then tie it into the new line, but here's the thing -- for all I know, it might have been the source of the leaks we were experiencing previously. Or it might have at least shared in them. This is a 30 year old pool with 30 year old PVC piping, so I don't put a lot of trust in the original stuff anymore. No, I would much rather just plug off the deep end and be done with it. Because if I wanted to replace the deep end piping and tie it into the new suction line, I'd have to get a backhoe out here and a two or three man crew to handle all the earthwork removal. This is a 10 foot deep pool, so I'd be looking at having to dig at least a 12 foot hole and then having to tunnel over to where the drain's outlet is. Thousands of dollars to repair what is ultimately a small water loss from a drain that this pool is getting by just fine without.

So unless I drain the pool, I'll probably have to get somebody out here with scuba gear just to plug off the main drain. And right now I'm thinking of something that would be quick but effective -- like plumber's epoxy putty. Ever seen the stuff? It's a stick of thick epoxy that comes in a tube. You cut off the amount you need, then kneed it until it is of a uniform color, then spread it or push it into the shape you need. It sets up in about 5 minutes, even if fully submerged in water. I'm thinking the epoxy can probably just be pushed into the drain's slots or holes or whatever it has under that cover. If it's just a hole, then perhaps epoxing in a piece of capped off pvc. Either that, or maybe we can use some sort of concrete mix that will also set up submerged. I know that such a thing exists, but I dunno how easy it will be to find it or how easy or hard it will be to actually put it where it needs to go. If I go the concrete route, I'd probably just want to completely fill whatever there is below the drain cover.

Any thoughts or suggestions on this? I bet you're gonna tell me I need to drain the pool to do it right, I'll bet. I'm still kicking myself for forgetting about that drain, but oh well. Chances are that, even if I would have blocked it off, I'd still have been looking at a leak situation.
 
Welcome to the forum! :handshake:

To be able to frame a couple questions, can you please add a signature. Read Pool School - Read This BEFORE You Post
Information in your signature will show up each time you post and it makes advice more accurate as we know what equipment we are dealing with.
 
Michael,

Tell us more about your Skimmer.. How many holes does it have in the bottom under the basket?

When you replaced the suction line, did you dig under the skimmer and install a new pipe into the skimmer, or did you just connect into an existing pipe?

Did you take any pics when you were doing it??

Thanks,

Jim R.
 
Welcome to TFP!

You won't have to drain your pool. I don't like the putty idea, at all. Even if that would work to seal up the drain cover (which I very much doubt), it won't take any less time underwater than installing a plug would.

Do fill in your signature as Marty is asking. He needs to see what you're dealing with. Some pictures of your skimmer, under the basket, would likely be helpful (that's where your drain line might actually be connected).

And one of your drain if you can manage it.

Are you sure your drain is not plumbed all the way back to the pad? Do you know what everything does there, what each pipe leads to? A picture of your pad would be good.

The drain line is not likely connected in some random location along the old skimmer line.

With any luck, you'll just need to install the correct-sized plug under your drain cover. A five-minute job for a diver. You could probably get an enthusiastic recreational diver to do the job for 50 bucks, if you want to roll the dice on the liability. Otherwise, use a pro who has his own liability insurance (yes, ask about it).

drain plug.jpg

If you get any hair-brained notion to attempt this yourself, by holding your breath, don't. Not even with someone on hand that knows CPR! Fun fact: the percentage of people that survive an event that requires CPR is not all that great.

Check it out:

http://www.shallowwaterblackoutprevention.org

Playing under water or swimming from one end to the other while holding your breath is one thing, working underwater is quite another...
 
Geez, what's up with this 5 line sig restriction anyway! Took me three tries to get it "right."

Anyway, as I was about to reply:

Jim, the skimmer has one hole, about 2" in diameter. I just plug my Hayward Pool Vac XL's hose into it and let the vac get after it.

When we replaced the suction line, we dug a 2 ft. deep trench up to the pool apron, and then we had to dig down about 3 ft. so we would be under the skimmer. There was a single line running into the skimmer and its connection was completely covered in concrete. We cut the line about 4" from the concrete and tapped in there. The old stub was still in good shape. No splits or holes we could see.

No, I didn't take any pics -- and dang it, here I call myself a photographer . . .

Dirk, thanks for the warning. I kinda figured out the hazards of diving into the deep end of a pool when I was still a young teenager, and could feel what felt like ice picks being jabbed into my ears. That's the sort of sensation that is independent of time. I know my limitations -- which is about 6 ft for maybe 30 seconds.

Yes, I'm quite familiar with the piping back at the pad. I even designed a slight improvement into it, which we installed when we put in the new line. There is only one line running up to the pump. Then a line from the pump to the filter, and a single line from the filter that disappears into the ground. We have two outlet jets in the pool. I'm assuming some sort of ordinary piping for the jets.

Okay, so under the drain cover there should be just one hole, I take it. Yeah, I like the idea of a rubber plug with the wingnut. Might be able to find some wingnut around here who'll even be willing to install it for me! Just joking!
 
Well color me incorrect. I can't imagine a drain would be plumbed in such a way that its flow could not be regulated, which generally means to the skimmer or to the pad. I'll look forward to the experts explaining that.

I suppose it's possible that it was done as expected originally, then somewhere along the 30 years it got reconfigured (like lopped off somehow and capped off).

Hopefully a simple hole is waiting the ol' cork under the drain cover...

Here's something to watch while the guys contemplate:

How to plug main drain for a leak in an underground swimming pool - YouTube
 
Michael,

Checkout this link... http://blog.poolcenter.com/article.aspx?articleid=6327

If you only connected to the one pipe that you saw coming out of the skimmer, then I can't see why that would cause your main drain to start leaking... :confused:

No matter how your main drain is connected to your skimmer, it seems to me that it should still be just like it was before you replaced the pipe that you did..

Have you actually done a bucket test, just to make sure you have a leak??

Thanks,

Jim R.
 
Yep, there it is: Old Style Combination Skimmer Plumbing: Anthony Pools & Sylvan Pools. What a lame way to plumb a drain. That would suck (see what I did there?). Michael, you think you might have one of those pools?

The problem is, even if you plug the drain, if that T is before where you tapped in, and there is actually a leak, then you've still got a problem.

Try the bucket test, first things first...
 
Still mulling...

When we replaced the suction line, we dug a 2 ft. deep trench up to the pool apron, and then we had to dig down about 3 ft. so we would be under the skimmer. There was a single line running into the skimmer and its connection was completely covered in concrete. We cut the line about 4" from the concrete and tapped in there. The old stub was still in good shape. No splits or holes we could see.

How well did you examine the concrete around the skimmer? Could there be a T embedded in it? Could there be a second pipe coming off that T, exiting the concrete in such a way that you might have missed it?

Or can you say without a doubt that the pipe you connected to runs directly to the skimmer bottom with no possibility of a T on it between your new pipe and the skimmer bottom?

Did you ever run the pump and observe the new and old pipe before backfilling?
 

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Dirk, thanks for the YouTube link. Good ol' YouTube -- the universal DIY resource :cool: That video led me to this one, which I found even more helpful:

Find Pool Leak how to with Dye Test And Fix With Pool Putty D.I.Y - YouTube

Good thing to look out for -- a leak under the lip of the drain. I wouldn't have thought of that. I guess pool putty is not unlike plumber's putty.

Unlike all the images shown in the blog link that Jim provided, this skimmer has a side opening for the suction line. There's something in the bottom that looks like it might be a capped off outlet, but it also looks like it's never been used. Excuse the crude drawing. I just whipped this up using Photoshop. This is an approximation of what the inside of my skimmer looks like.
pool_skimmer_1a.jpg


I'm running YouTube in the background as I type this up, and it's on another video now. One thing they mention at 20:45 is that it is a law in the US to have two main drains. Guess this pool was built before that law was instituted. Here's a link:
How To Build A DIY Inground Pool Kit From Pool Warehouse! - YouTube

I'll see if I can get a decent pic of the cover for the main drain. It's raining right now, so the water surface is all jumbled, and kinda dark outside. Looks like there are two large screws or bolts that secure the cover -- I was able to make out that much.

Guys, I don't know what the "bucket test" is. Care to explain? Or should I just do a search here?

Okay, this is the reason why the main drain is causing a leak. I'm assuming here that it was tied into the existing old suction line somewhere. The water level of the pool is approximately 1.5 feet above the level of the new and old suction lines. So this means that the main drain will attempt to drain water out to that level. Basic flow physics, right? And since it is connected to an isolated piece of piping that is open on both ends there is nothing preventing the drainage of water from this old piping. I suppose one way I can tell is to look for soggy earth in these two areas. The one by the pool may be harder to notice because it is closer to 3 ft. deep, whereas the one closest to the pump is somewhere around 2 ft. deep. Dirk, there was no T ahead of where we tapped into the line. It was only about a 4 inch stub protruding from the concrete. That was the only visible projection out of the concrete. And, given that the box shows only one outlet, that makes sense.

Dirk, I dunno if this is an Anthony or Sylvan pool. More likely some local pool contractor, I'm thinking. But the skimmer box is different from the A & S design that is shown in the blog page Jim provided.

Yes, we ran the pump before we filled the trench back in. I wanted to double check that there were no leaks before we covered everything up. We probably ran it for a good 15 minutes after the air was finally purged from the system.
 
Okay, I read up on the bucket test. Easy enough. Now to find a bucket . . .

What I use to judge the drop in water level is the mosaic tile on the side of the pool. Here's a pretty dreadful pic of our pool. Shows the general shape of the pool and position of skimmer box, and also shows the mosaics -- although rather faintly -- that I use as an indicator to judge by how much the water level is dropping. Each mosaic square is about 1.25" on a side, so I can guesstimate pretty accurately how quickly the water is dropping.
backyard_4b.jpg


This pool had a diving board that was uninstalled sometime in the distant past. Hence the 10 foot depth and 20,000 gallon approximate capacity -- and the fact that about 60% of the pool is deep end (deeper than 6 feet). Note the location of the pump shed -- the only part of it that is visible is that angled piece of fiberglass roofing material behind the pool and to the right -- in deep shade.
 
OK, you found the bucket test. Run that. That'll tell you a lot.

Yes, there is a law about the drains, but that's if you are installing one. If you have a new drain system, it must be two drains (it's actually not that simple, there are other options), but you are not required to have a drain, so no drain is legal. There is no retroactive component. They can't make you add a drain or two. Capping yours off solves all the safety issues, in the spirit of the law at least.

A picture of the drain was just to determine what it looked like. What we really need to know is what's under the cover. But don't kill yourself trying to get a picture of it!

Your explanation of where the leak might be makes some sense. Capping off the drain would be prudent even if there isn't a leak, as it might cause a problem in the future. But if you abandoned the old skimmer line, without capping it off, and the drain was plumbed to it, would the pool be flooding through that open pipe? Or did you glue a cap onto the old pipe?

Paying someone to do what that guy was doing in the video I linked would not be the worst thing. You'd get the drain capped off, and he could test the whole thing for leaks.

If you're sure your drain cannot be connected between new pipe and skimmer, then I think you're on a good path for a solution (if, in fact, there is as leak in your old drain).

But let's get the bucket test result first...
 
I’m having a hard time following OP descriptions.

I gleaned reference to A&S protocols, throw that out the window - a&s is not predictable if they can save a a buck in material, the PM bonuses.

OP photos of modified or premodified work?

Anything that touches water can leak.

Jim- my Southern friend, air locking is a New England winterization ritual. Plenty of threads here for a quick study.

OP - where how do believe drain was in service?
 
OK, you found the bucket test. Run that. That'll tell you a lot.

Okay, I'm on it. What's a typical time frame for this? 24 hours? More?

A picture of the drain was just to determine what it looked like. What we really need to know is what's under the cover. But don't kill yourself trying to get a picture of it!

Well the crude sketch I provided above gives you most of the salient data. But I'll see if I can come up with a photo. The weather is still miserable and dark. But if it brightens up at all I'll get out there and take a couple of pics.

Your explanation of where the leak might be makes some sense. Capping off the drain would be prudent even if there isn't a leak, as it might cause a problem in the future. But if you abandoned the old skimmer line, without capping it off, and the drain was plumbed to it, would the pool be flooding through that open pipe? Or did you glue a cap onto the old pipe?

Nope, no caps of any sort. I'll admit to a brain fart on that one. You know, I used to design pumping and piping systems as part of my job description, but that was over 30 years ago. And when you're out there working while the hot Texas sun is beating down on you, a person tends to get preoccupied with getting things done soonest. There's just the old, leaky suction line that's open on both ends, but buried beneath a couple feet of dirt, into which the main drain is tied at some point. If I had to guess at the tie-in point, I suspect it would be at a point in the old line where a perpendicular line could be drawn between the drain and the old suction line. And, yes, the pool flooding through the open pipe is precisely what I think is happening. But it isn't so much a flood as it is a slow trickle, apparently.

I’m having a hard time following OP descriptions.

OP photos of modified or premodified work?

As I mentioned above -- Nope. Just didn't occur to me at the time that I should document it.

OP - where how do believe drain was in service?

Not following your grammar there. Can you rephrase please?

You know, something just occurred to me. We know next to nothing about this pool's history, and the previous owners, who had owned this property for only a few years -- they'd bought it as an income producing investment and rented the place out -- knew next to nothing about it either. All they knew was the pool was about 30 years old. Oh, and that was four years ago, so that actually makes the pool 34 years old now. I suppose I can find a city or county planning department, where permits had to have been issued, and find out something about it that way. I'll need to research this some, but it's the only possible avenue I can think of that might bear fruit.

I mention the above because of this: shortly after we bought this house, both the pump and filter failed. The pump stopped working and the filter canister split right down the middle, from top to bottom. Talk about a catastrophic failure! Both the pump and the filter were Hayward. But the canister, which uses a cartridge similar to the one we have now, is tiny by comparison. Way undersized for a 20,000 gallon pool. And I strongly suspect that, based both on the style of the canister and the existing piping, that this pump/filter arrangement wasn't original. Given its severe undersized capacity, it smacks to me of a DIY special. Perhaps even the piping to and from the pump and filter were DIY -- or at least, a portion of it. So, it got me to wondering -- perhaps the main drain's original line was plumbed up to the pump, where it would have joined with the skimmer line prior to entering the pump? And perhaps there might have been all the diverter valves and what have you located there at the pump originally. I can just see some yahoo looking over a somewhat complex piping system and muttering, "Who needs all this junk?" and tearing it out, and then replacing it with what's there now. If this was, in fact, what happened, then my guess is that it probably happened some time within the past 10 years, and I base that solely on the broken filter canister, which is of a recent Hayward design. But then again, I don't know how often Hayward changes its designs, so I might be off by a fairly wide margin.

I just had another thought. Our pool guy has been servicing our pool for about 12 years. This means that he was around before the previous owners owned this house. So he probably knows more about the history of this pool than anyone else. I just called him, but he's busy and can't talk right now, so I'm gonna call him later and see what he knows about this pool's history. Stay tuned . . .
 
That was one of my original guesses, that if the main drain doesn't plumb to the skimmer, then it might have been plumbed to the pad, and then at some point got lopped off for some reason.

And I was referring to a picture of the drain, not the skimmer, to determine if it could be capped off, and what is needed to do it. But, again, that's under the cover and going to require someone to go down there to remove the cover and see what's up.

Seems like you have a few choices, mostly about who's going to do what, and in what order.

If you can somehow find the other end of the drain line, that'd be good. Then you could safely ignore the remaining old skimmer line.

But even if you can find it, and if you've got a leak, then that won't help you much.

I think either way you'd need to cap the drain line at the drain (unless you don't actually have a leak). And if you use a leak detector scuba diver specialist to cap the drain, he can test the drain at the same time and that might be the end of it.

If the bucket test reveals your pool is leaking, and you can't find the leak, then you kinda gotta get someone out there that can, right?

Bucket test instructions (12-24 hrs).
 
I'm in agreement with pretty much everything you just wrote.

I didn't get ahold of the pool guy yesterday. He told me to get ahold of him after work, and I just plumb forgot. Also, I haven't found a bucket yet. Still looking -- I know we're bound to have one around here somewhere. If nothing else I'll go down to Wally World and buy one.

Something else just occurred to me. Assuming a previous owner removed the original piping at the pad and replaced it with what's there now, I'm wondering what the likelihood is that the main drain may have been isolated at this point, and that it was never reconnected to the suction line . . . just another possibility to mull over. I suspect that, if I were to dig down around the pad for evidence of old piping, I might find something. Problem right now is access. The pump shed is in the way of getting down to where the old piping might be found.

I can take a pic of the drain cover if you like. It's just a round, vented cover, with two bolts holding it in place. I agree, it's what's under the cover that is gonna matter.

I've discussed the situation with my wife, and she doesn't care for the idea of having to hire anybody to plug off the drain. She's the one who pays the water bill around here, so she has a dog in this hunt. And she wants to drain the pool. If we go that route, we'll have to wait, I suspect. The ground is saturated from all the rain we've been having, and I've read of pools actually popping out of the ground after being drained if the ground is too saturated.
 
Why does she want to drain the pool? (The same one guarding the water bill?!?) Ya lost me there.

Yes, a pool can float out of the ground, but that's not the only risk. It's not a casual thing to do, even if you're sure of your water table. The cost of water aside, you need to be mindful of the plaster. How old is it? Plaster can bubble up when exposed like that. The sun is one factor, but weak plaster (from age or chemical abuse, or even poor installation) is sometimes held in place only by the weight of the water (its a lot of weight). When you remove that force, the plaster is free to do its thing, which sometimes manifests as blisters, that usually pop off. And this blistering can occur even after the water is restored, because the damage was done. I had this happen in my pool, so I've actually seen it for myself. That plaster was only five years old.

My current strategy: do everything possible to never empty the pool: take TFP care of the water, eliminate the need to replace water (like by filling with soft water to eliminate CH build up) and by making use of the exchange-water-without-emptying method should I ever need to (due to the inevitable salt build up). And my plaster is new! I'll never expose it if I can avoid it.

Hiring a specialist is dirt cheap compared to damaging plaster...
 

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