Can a Pool Really Pop Out of the Ground?

A drained pool looks harmless until you realize it can become a boat. We’re talking about pool pop-ups, the real-world risk behind the phrase “the pool can pop out of the ground,” and the simple physics that make it possible when groundwater rises under an empty shell.

We walk through what actually holds an inground plaster or concrete pool in place, including the massive weight of thousands of gallons of water, and what changes the moment you drain it for an acid wash or to lower high cyanuric acid. Then we get practical: how heavy rain, wet seasons, saturated clay soil, and even where you discharge water can raise the odds. If you’re servicing pools in higher-rain regions like parts of Florida or Louisiana, we also talk about hydrostatic plugs, what they’re designed to do, and the tradeoffs you should know.

Fiberglass and vinyl liner pools get their own warning label. Fiberglass shells are light enough that pop-up risk is much more real, and draining can also lead to wall bowing, cracking, or collapse. Vinyl liner pools can turn into an expensive disaster if the liner pulls out and tears, especially as the material loses elasticity over time. We explain safer partial-drain thinking and why calling the right specialty company can save your customer’s pool and save your liability.

If you found this helpful, subscribe so you don’t miss the next one, share it with a pool pro who’s been debating a drain, and leave a review so more people can find the show.

We break down what “pool pop-up” really means, why it happens, and why it’s far less common than the horror stories suggest for most concrete pools. We also lay out the big red flags when draining fiberglass and vinyl liner pools, plus how weather, groundwater, and soil type should guide every drain decision.  
• how groundwater and buoyancy can lift an empty pool shell  
• why heavy rain and clay soil increase pop-up risk  
• practical timing rules for safer pool draining and refills  
• why fiberglass pools are higher risk when drained  
• how hydrostatic plugs work and when they matter  
• why vinyl liner pools can tear when fully drained  
• when to call a fiberglass installer or vinyl liner company  
Learn more at swimmingpoollearning.com.  
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Transcript

Welcome And Today’s Warnings

SPEAKER_00 0:14

Hey, welcome to the Pool Guy Podcast Show. In today's episode, I'm going to talk about pool pop-up and also some cautions when you're draining a fiberglass pool or vinyl pool. And pool pop-up is something that you get everyone talks about in the industry. And is it really a big deal problem? Is it something to worry about? I'll cover that here. And of course, the cautions with draining certain pools and what you should do and what you shouldn't do. Are you a pool service pro looking to take your business to the next level? Join the pool guy coaching program. Get expert advice, business tips, exclusive content, and get direct support. From me, I'm a 35-year veteran in the industry. Whether you're starting out or scaling up, I've got the tools to help you succeed. Learn more at swimmingpoollearning.com. I'll start with this first one because this one I get asked a lot by people new to the industry when a customer wants their pool drained, for whatever reason, you know, maybe they want to replace the water because there's too much cyanaric acid in there, or they want the pool acid washed. The question I get often is what is the real danger of that pool popping out of the out of the ground when you drain it? And the answer is there's really no national statistics about pool pop-ups. I can tell you that a builder in Florida that I know, throughout his lifetime of building pools, has only had two of these happen. And they were just waiting for that. And then of course Florida had tremendous rainstorms, which they usually have ever so often. The ground got really saturated, and these two unfinished pools at two different time periods

The Physics Behind Pool Pop-Ups

SPEAKER_00 2:00

got popped out of the ground, which is pretty catastrophic, and you know, fixing that is not an easy thing to do at that point. I I really don't even know how they fixed that, to be honest with you. But here in my area of Southern California, it's even rarer for the pools to pop up. However, we have been having a lot more rain the last five years than we've had probably in the last 20 years, and so the the danger probably is somewhat increasing. But how you know, how does the pool actually pop out of the ground? And what's the science behind it? Well, when you drain the pool, you only have the weight of the pool shell, which is logical. Water's pretty heavy, you know, it's like it's around eight pounds or a little over eight pounds per gallon of water. So if there's a 15,000 gallon pool, I could do a rough calculation here. So 15,000 times 8.3, that's 124,000 pounds. That's that's a pretty that's a lot of weight in that pool holding it into the ground. But when you empty it out, you just have the shell, which probably weighs about 10 or 15, 10 or 15,000 pounds. It's not super heavy because it's just the cement, it's pretty heavy, but it's not super heavy without the water in there. And what happens if the ground gets really saturated? This is something that's gonna take like six or eight, six or eight inches of rain. And the soil type also matters. So if it's like a clay soil, it's going to absorb the water more than say sand or rocky soil, and so the actual displacement on wet soil, it depends on how much how far the water gets underneath the pool. For example, if the pool is six feet deep and about two feet of the dirt underneath gets saturated with water, that could be almost enough to push that pool out of the ground because the displacement of water, the weight of that can lift up like a hundred thousand pounds of an object. If you know the force of water, it's a pretty powerful force. Imagine that water underneath it just pushing up on it, and it's the pool's gonna be more buoyant and it'll just push it right out of the ground. Extremely rare again in California and most of the west coast, but not quite as rare in those, you know, the panhandle, Florida, Louisiana, those areas that get tons of rain and have more marshy kind of clay-like soil. It could happen if you get a ton of rain or if you drain the pool right there into the dirt, it could get saturated with water and cause that effect where the groundwater pushes up whatever's above it because it can displace that weight pretty easily, and that could cause the pool to pop up. Now, of course, you could be paranoid about it and you can worry about it, but will it really happen to you? Probably not if you're smart about it. You don't want to drain a pool after a major tropical storm, nor would you want to build a pool and leave it empty right before the tropical season where you can get like eight inches of rain, which happened to the pool builder I know in Florida. It's something to consider. But I wouldn't lose sleepover, and I wouldn't defer draining a pool if it's safe to drain or acid wash. And again, here in my area, I think the most rain I've ever experienced was like one day where we had three inches of rain from 6 a.m. till midnight. And three inches of rain is like just one hour in parts of Texas when it's raining really hard. Use your

Rain, Soil, And Smart Timing

SPEAKER_00 5:30

common sense. Don't drain a pool for an acid wash or refill right after a major storm like that, because you really don't know the groundwater, and you don't really know what how much water is actually under the surface there. And err on the side of caution and don't drain the pool during the wet rainy seasons. Drain them in the summer, drain them in the times of year where the ground is hard as a rock, and you're not going to have that displacement because again, a plaster pool empty is about 15,000 pounds, which is really heavy. And if the ground is dry, that pool will never be pushed out. When I was a kid in my neighborhood, there were two pools that were always empty. No one they never filled them up or re-plastered them. And we would actually use those. A lot of my friends would write skateboards in them. It was really cool. And probably to this day, those pools are still empty. I don't know. I was a kid, so maybe it's a long time ago. I'm sure that people that bought the house has filled it up by now and remodeled the pool. But it probably was about five or six years where that where I knew that pool was empty and never had a problem with it popping out of the ground. And there's been repos back in 2008 and 9 that I serviced where they drained the pool down and left them empty until the new buyer bought the house, and those were empty for like a year. Never popped out of the ground either. So it's not something that's common, so I wouldn't worry too much about it. And it's one of those kind of fear-mongering things that you hear a lot about in the industry. You know, the pool pops out of the ground, and you're gonna it's you can't drain it. Now, fiberglass pools, a different story. If it's a fiberglass shell pool, it's really light. The actual only pool pop-up that I've ever witnessed in my life. I just started out in the business. I was working for a company in Ranch Cucamonga, California, and it was a fiberglass spa, and we had drained this thing. It was it had a wood deck and it was a fiberglass spa, pretty small little thing. If we had drained it to clean it because it had a lot of staining in it, and we had this really big rainstorm, one of those rare ones where we have again three inches of rain in that whole day. But that was enough rain to get underneath this little fiberglass spa and actually pop it right out of the ground. Now I'm not sure, I can't remember how we fixed it. I think we dug everything out, removed the deck, it was like a big mess to put it back in the ground. But a full-size

Fiberglass Pools Can Lift Or Fail

SPEAKER_00 7:45

fiberglass spa only weighs about 2,000 to 4,000 pounds, which is not a lot of weight if you think about it. You know, that's like an elevator, I think, has like a maximum weight of like 2,000 pounds or something like that. So it's not really a lot of weight in the fiberglass shell because it's just a piece of fiberglass dropped in there. And if you were to drain that pool, which I don't recommend doing, you know, the refill it, maybe drain it down halfway and put fresh water in, or one-third of the way and put fresh water in. But there's really nothing holding that fiberglass pool in, and you get into a lot of danger or danger zone when you drain a fiberglass pool because the pop-up, the pop-up ability or the factors dictating pop-up are different for fiberglass pools than a cement pool, and you're more likely to have a fiberglass pool. In my opinion, across the country, I bet a lot of the pops up for fiberglass pools, but you would probably have a better chance of a fiberglass pool popping out of the ground than a fully cement pool. And you definitely want to have liability insurance to cover yourself if you ever run into a pop-up experience, which I don't think you ever will in your career, but it could happen. Now, I mentioned the panhandle, Florida. A lot of those pools have what's called hydrostalic plugs. And these are supposed to be a safety mechanism to prevent pool pop-up. How they work is that when the pool is full of water, the weight of the water keeps them pressed down into the into the floor of the pool, they're not going to activate. But if you drain the pool and the pool's empty and there's no more pressure on them, and the water table rises under the ground, let's say that you have these pools empty, you have the hydrostatic plugs in there, and it rains eight inches in you know that a three-hour, five-hour period, whatever. Well, the groundwater is going to be really saturated at that point. So, what happens is that the spring or the plunger valve pops upward, and this allows the groundwater to flow into the pool shell. Now, it's it's something

Hydrostatic Plugs And What They Do

SPEAKER_00 9:55

that is going to cause a big mess, of course, but the groundwater will actually come into the pool and fill the pool up and not push the pool out of the ground, basically. These can also be a kind of fail area of the pool where water is leaking, so just be be aware that they can cause a leak as well. And there's two types there's the spring-loaded ones that are automatic, and then there's the manual plugs. And a lot of the pools probably have the manual plugs when you pull them manually, and you may want to pull these when you drain a pool and the panhandle, just to be cautious. And you could pull these manually, and this, of course, if anything odd happens, like a serious storm, then I definitely would say that would probably save you from that the major problem. Sometimes though they're hard to pull and they're hard to put back in, and it's really better just to watch the weather and plan accordingly at that point. I don't think I've seen a pool here in California with these hydrostolic plugs in them. Again, we don't have that problem, so the builders don't really put them in. But you can pull up schematics, you can go online and pull up schematics of them. It's pretty interesting to see these things and to kind of see how this would actually work to prevent that pop-up. And so you may they're like little plastic if you're not familiar with them. They're threaded into the bottom, and they're they have a little plastic cap on there, with you know, there's an O-ring in there as well. And again, it's pretty interesting to see these. If you're in Florida, you probably see them all the time. But I don't think I've seen one yet here in Southern California, to say the least, probably maybe Northern California has some. But again, if you're interested in learning more about them, which you probably should if you're in the panhandle area, you should definitely pull up schematics and get familiar with them and get familiar with the spring-loaded ones and the manual ones and when you would utilize them when you're draining a pool. The last pool type I'll talk about are the in-ground vinyl pools. Now, again, these aren't super popular in my area, they do exist, and they're really popular like in North Carolina, those areas in the East Coast. And these in-ground vinyl liner pools should really never be drained by a pool tech. They should be drained by a vinyl liner company. They kind of know how to do it properly because a lot of things can go wrong when you drain a vinyl pool. And I've had these vinyl liner pools on my route, and the problem is that the as the liner, as the vinyl liner gets older, it does lose some of its elasticity. I can't pronounce that word correct. Elasticity. So anyway, it doesn't stretch as well, I should say, in layman's term. And what happens when you drain

Why Vinyl Liners Shouldn’t Be Drained

SPEAKER_00 12:40

the water down in these pools is that they're gonna start it's gonna start to pull away from the sides where it's tucked in at the top. And once that vinyl liner pulls out of there, if you had any of these on your rat, you'll know that they're gonna tear basically holes right along the edge there, and you're gonna have to get a new liner put in at that point. But a professional vinyl liner company actually has a method they use where if you ever see this being done, they have a hose and they put they use air pressure, they use like a vacuum and they use atmospheric pressure to kind of pull the liner or push the liner firmly against the pool sides. It's complicated to explain here, but they have a method that's effective so that the liner doesn't tear, and so that's why if you're draining a vinyl pool, I would say draining it down maybe one-third or half of the water is acceptable. Anything more than that, you have a good chance of that liner tearing or stretching and tearing off the side of the wall and ruining the liner. So basically, they have a method that they use that's really effective. And if you do need to drain a vinyl pool down for whatever reason, I definitely would call the professional companies that do this for a living, they have all the special equipment and they know exactly how to do this without the vinyl liner being damaged and having you to buy a new one, which is really expensive. I should go back to the fiberglass pool one more time. When I talk about draining it and not draining it, it could pop out. But also the walls are really thin material as well, and they can actually bow inwards and crack and collapse. And if you if you s I think there's a fiberglass company, can't remember the name, but they have a video on this happening or shows you what would happen if you drain it. And it's one of those things where again, I wouldn't drain a fiberglass or vinyl pool. I would let the experts do it. It's something that's going to prevent liability. And you know, I think here uh there's a few fiberglass companies that will do it or that actually put the fiberglass pools in. I'd call one of them and say, hey, I have a fiberglass pool, the water needs to be drained, it's you know, it has really high cyanuric

Real Odds, Liability, And Wrap-Up

SPEAKER_00 14:50

acid. Can you come and drain it? And they'll come out and do it professionally, they know what they're doing, and it's something that they know they know more about it than you would know. Same with the vinyl liner pool, just call the professional vinyl liner company to do it. And for an in-ground pool, of course, it's pebble tech or s or plaster, really very little danger of it popping out of the ground, especially on the west coast. Maybe you have to be a little more cautious in Florida, Georgia, Louisiana, those areas where the ground can get very saturated. And again, I was looking for stats and I used AI to try to find some stats, and basically the only thing it found is that maybe 150 to 300 in-ground pools actually pop out every year, which with like 6 million in-ground pools out there, that's the chances of that happening are 0.003% to 0.005%. So for real worlds, real world stats, it's like it's like 1 in 20,000 or 1 in 30,000 that would happen. Those are the same odds of being hit by a car as a pedestrian, which is one in 21,000. Or if you play poker, it's being dealt a royal flush in Texas Holdem, the first five cards without turning any cards in. That's one in 30,940. I guess that means that if you're playing poker with your buddies and the and the you get the royal flush dealt to you, you probably don't want to drain any pools for the rest of the year. Looking for more podcasts, you can find those on my website, single learning.com. Just go to the podcast icon on the banner. There'll be a drop-down menu of over 1900. I was gonna say 30,000, but not quite there yet. 1900 podcasts for you there. And if you're interested in the coaching program, you can learn more at poolguycoaching.com. Thanks for listening to this podcast. Have a rest of your week and God bless.