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Thread: Ground water behind liner - Inground Pool

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    Ground water behind liner - Inground Pool

    Hi All,


    New to the site and thought I would ask some of the experts out there about this topic. My neighbor and I had pools put in three years ago and the company we dealt was a reputable pool installer(we did some research) just outside Toronto, Canada. At the time the pools were installed they put in a drainage or a vacuum pipe as I believe its referred as to the side of the pool(approx. 4-5ft in the ground). After heavy rainfalls or thawing after winter we are constantly running our pumps to get rid of the ground water that builds up essentially behind the pool liner. I am very thankful that this was put in at the time of install as I never recall growing up friends having such a system for ground water. At the time I was told it was done due to the water levels in our area being high, the only thing I cant figure out is my brother in law had a vinyl liner pool put in at his place and he is in the same subdivision but different company and he never has any issues with water behind the liner. May be a different type of drainage system was put in that him nor I are aware of. Anyways long story short, I just wanted to ask those out there in the business is this typical practice with vinyl liner inground pools these days due to the way subdivisions are built? I find every spring im pumping out plenty of water especially after these last two brutal winters and pushing out quite a few wrinkles with the brush once the pool is open. It was certainly something that they didn't mention when we signed up for the pool. lol I just want to know if this is all normal practice these days with inground pools?

    Thank you.

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    Swampwoman's Avatar
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    Re: Ground water behind liner - Inground Pool

    Greetings, and welcome. Addressing water table issues is a good "best practice" though perhaps not as prevalent as it should be I believe its both site-specific and a sign of a conscientious builder I have mine plumbed to the main pump to reverse flow to empty it as my pool sits where a former catch basin was on the side of a hill. It discharges the water into a French drain system built around the perimeter of my pool. I'm on a 2.5 acre parcel, so I don't suspect subdivisions have anything to do with it

    My liner has not ever floated, even though the pump is shut down in Winter. I suspect this is due to the French drain, but it also helps that I open early and pump any time there's 6" of rain over a fe days. Perhaps your brother-in-law whose liner doesn't float has additional passive drainage on his site, or his elevation is better.
    In ground extended Grecian, 22,000 gal, Hayward 220t sand filter, vinyl liner, dolphin m4 supreme.
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    Mod Squad tim5055's Avatar
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    Re: Ground water behind liner - Inground Pool

    It seems like the pool builder took local conditions into account and made provisions for the high ground water. Sump pumps and other methods of keeping the ground water level down are unusual, but not unheard of.

    I would yield to someone with greater knowledge in this area, but my gut reaction is that it is normal.

    Ground water is something that must always be taken into consideration. My lot is in a subdivision and we are the low lot. After heavy rains I actually have water pushing up through the cracks in the driveway due to the high water table. Luckily I have a gunite pool so I don't have similar issues as you, but in my case I must be careful when draining water not to actually float the pool out of the ground. Every pool installation will be slightly different.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Ground water behind liner - Inground Pool

    Thank you for the replies, much appreciated. I suspect it's all normal behavior and we are essentially in the middle of the slope down in the grading to the storm drain several houses down. I have an inlet/outlet pump that does about 1500 gallons/hour to drain the pipe and I am usually on top of it as soon as there is a heavy rainfall or the spring. It's just something I have never seen before, but I am grateful it was put in place. From what I have read there are quite some horror stories of the liner being completely pushed up from ground water and people essentially walking away from homes. It's just amazing how much ground water you can see at times that gets behind the liner and I just wanted to be sure that this is normal practice for pool installers due to the drainage/grading of homes in subdivisions. Especially those where the water levels tend to be higher. My brother in law does back onto a park so it is possible they put some type of drainage in the ground towards the park to address any ground water.

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    Mod Squad tim5055's Avatar
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    Re: Ground water behind liner - Inground Pool

    Oh, and where are my manners.....

    Welcome to TFP. We hope you stick around a while and read up on our pool care methods.

    As many time answers to questions are geographically significant, could you narrow down "Canada" in your profile and it would help us if you would add the following information to your signature


    • The size of your pool in gallons
    • If your pool is an AG (above ground) or IG (in ground)
    • If it's IG, tell us if it's vinyl, plaster/pebble, or fiberglass
    • The type of filter you have (sand, DE, cartridge) and, if you know, the brand and model of the filter.
    • If you know, please tell us the brand and model of the pump, and mention if is it a two speed or variable speed pump.
    • Date of pool build/install, particularly important if less then a year old.
    • What kind/model of water test kit you are using
    • Other significant accessories or options, such as a spa , SWG, or cleaner
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Ground water behind liner - Inground Pool

    My apologies and thank you for the welcome, I have become quite aware being a pool owner these days. Last year was the first year I attempted to open and close my pool(attended a seminar from my installer). very comfortable in doing this now. I have updated my signature with the pool contents.
    Toronto, Canada - 56,243 Litres(Canada) :) US 14.86 Gallons Inground Pool - 14x16x32 Capri - Vinyl Liner Salt Water Pool (Zodiac Nature2 Salt Generator) - Hayward Pump(will provide details) - Pool Install May 18, 2012 - Water test kit at local pool store or with store bought kit - Haven't decided on a pool cleaner just yet, but getting tired of manually doing it.

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    Re: Ground water behind liner - Inground Pool

    Hi All,

    Sorry to rehash this thread, but its basically along the same lines. When our pool was constructed a vacuum pipe was put in place which removes as much ground water away from the pool due to a high water table level. I've been trying to figure out easier way in the spring/summer to deal with the ground water behind the liner. It seems like its a constant battle, I use a simple inlet/outlet pump to remove the water from the pipe. To me it doesn't seem like an efficient way to do this, so usually i end up removing a piece of the coping(twice a year) slide the hose down the back of the liner to the bottom and drain the water this way. This seems to be the most effective and the liner with the weight of the water move right back into place. What I'd like to ideally have in place is a submersible pump that could fit in a 4 inch pipe with a float that continually drains as the water fills up in the pipe. I haven't been able to locate one and I find the current 1/2 HP pump I have is effective at removing the water but after about 20 minutes its simply waiting for water to once again fill up in the pipe(too powerful a pump I think). I'm not sure whether I am continually dealing with this due to poor pool construction or what, but again just thinking of a way that I can be more efficient at removing the ground water from the pool. Any suggestions would be greatly appreciated.
    Toronto, Canada - 56,243 Litres(Canada) :) US 14.86 Gallons Inground Pool - 14x16x32 Capri - Vinyl Liner Salt Water Pool (Zodiac Nature2 Salt Generator) - Hayward Pump(will provide details) - Pool Install May 18, 2012 - Water test kit at local pool store or with store bought kit - Haven't decided on a pool cleaner just yet, but getting tired of manually doing it.

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    Re: Ground water behind liner - Inground Pool

    There are pool cover pumps with a shut off float that works like a typical sump pump. Once the water level retreats to a level below the float, a switch will cut off power to the pump. I don't know if this arrangement will fit your 4 inch pipe, but it might be worth a look.
    22,000 gallon ig vinyl solar heated (panels and cover) zeolite filtrate

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    Swampwoman's Avatar
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    Re: Ground water behind liner - Inground Pool

    Show time, this is by no means "easier" but I am letting you know about it for whenever you next replace the liner so that a retrofit is at least an option.

    My pool was built in a former catch basin in the side of a hill, so the original builders did some fancy stuff to make it work The pool builder dug a sump under the deep end and plumbed a line, connecting it to my pump system. To pump out the sump merely requires closing the other valves and opening the line. The water can either be filtered and added back to the pool or discharged to waste.

    I don't know that this is the only thing that has kept the liner snug for 15 years now, because there is also a French drain around the perimeter of the concrete covered by larger landscaping stones that also serves to channel water away, which is connected to other drainage on the property. But I do know that however major the snowmelt in spring, that liner is snug as an army bed sheet

    I don't know what a retrofit might cost when changing the liner since you'd also have to reconfigure your lines a bit, but you might enjoy the convenience. Others who do drop a pump into a well (if you found one that fit...other builders will put an automatic pump down the well itself in a kind of sump dug beside the pool) have found they tend to burn out quickly, which is likely why your builder didn't integrate one. That's what I like about having it plumbed to the pool system, though this isn't useful when the pool is closed for the winter, for obvious reasons

    Since purchasing this property, ive learned that the company that built this pool is well-known locally as the go-to groundwater problem guys, but I have read in pool tech papers that this is a valid/not unheard of way to do it. So your builder might have heard of/read about this approach, but it might just be that it adds more cost than acceptable in a competitive bid.

    When my pool was built by the original owners, three other companies had declined to bid because they basically said it couldn't be done in the footprint So I'm told there wasn't a competitive bid, just an imperative to make it work!
    (For which I'm really grateful!)
    In ground extended Grecian, 22,000 gal, Hayward 220t sand filter, vinyl liner, dolphin m4 supreme.
    If TFP has helped you, please click to SUPPORT TFP!
    Helpful Links:
    GET A TEST KIT Chlorine/CYA Chart How to SLAM About Metals & Stains

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    Re: Ground water behind liner - Inground Pool

    Quote Originally Posted by Swampwoman View Post
    Show time, this is by no means "easier" but I am letting you know about it for whenever you next replace the liner so that a retrofit is at least an option.

    My pool was built in a former catch basin in the side of a hill, so the original builders did some fancy stuff to make it work The pool builder dug a sump under the deep end and plumbed a line, connecting it to my pump system. To pump out the sump merely requires closing the other valves and opening the line. The water can either be filtered and added back to the pool or discharged to waste.

    I don't know that this is the only thing that has kept the liner snug for 15 years now, because there is also a French drain around the perimeter of the concrete covered by larger landscaping stones that also serves to channel water away, which is connected to other drainage on the property. But I do know that however major the snowmelt in spring, that liner is snug as an army bed sheet

    I don't know what a retrofit might cost when changing the liner since you'd also have to reconfigure your lines a bit, but you might enjoy the convenience. Others who do drop a pump into a well (if you found one that fit...other builders will put an automatic pump down the well itself in a kind of sump dug beside the pool) have found they tend to burn out quickly, which is likely why your builder didn't integrate one. That's what I like about having it plumbed to the pool system, though this isn't useful when the pool is closed for the winter, for obvious reasons

    Since purchasing this property, ive learned that the company that built this pool is well-known locally as the go-to groundwater problem guys, but I have read in pool tech papers that this is a valid/not unheard of way to do it. So your builder might have heard of/read about this approach, but it might just be that it adds more cost than acceptable in a competitive bid.

    When my pool was built by the original owners, three other companies had declined to bid because they basically said it couldn't be done in the footprint So I'm told there wasn't a competitive bid, just an imperative to make it work!
    (For which I'm really grateful!)
    Thank you for the reply, its funny you are the second person to mention this method to deal with the ground water. I have the pool company coming out this week to have a look and i will mention this possible approach. I told them i'm willing to pay, but I do think part of the cost should be taken care of by them as this was a miscalculation on their part in regards to the amount of ground water we deal with. The pool was only installed three years ago so you can imagine the frustration because I know there has to be an easier way to deal with ground water than this. I know lots of people with pools installed and they never have to deal with this stuff(i do understand that this is always based on elevations and water table levels in the area). However, I think once they realize that the water table level is high they need to deal with it in the engineering of the pool install. Also, noticed you are in Grand Rapids Michigan, my brother also lives there. Thanks again.
    Toronto, Canada - 56,243 Litres(Canada) :) US 14.86 Gallons Inground Pool - 14x16x32 Capri - Vinyl Liner Salt Water Pool (Zodiac Nature2 Salt Generator) - Hayward Pump(will provide details) - Pool Install May 18, 2012 - Water test kit at local pool store or with store bought kit - Haven't decided on a pool cleaner just yet, but getting tired of manually doing it.

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