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Thread: Is pool overflow drain recommended?

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    Is pool overflow drain recommended?

    We have having our vinyl pool liner replaced and also partial replacement of the slab since some areas have been settling over the years and mudjacking didn't help. My neighbor, who also owns a pool, recommended that we ask to have an overflow drain installed while we're having this work done. I asked my pool contractor, who's been in the pool business for 25-30 years about this and he said he wouldn't recommended it. He said it's an extra expense and when the kids swim and jump in the pool and create waves we will be losing water through that overflow drain. However, I have since found some overflow drains online that have a closing mechanism. Our main concern, of course, is pool overflowing during heavy rain. Our contractor said that pool overflowing is not a big deal and we shouldn't worry about this because it won't cause any damage. All I know is that in the last 5 years of owning this house/pool we tended to worry about heavy rain and pool overflowing (mostly at night, when we can't monitor it and it rains heavily or when we're on vacation). So, should we stop worrying about the pool overflowing or would it be wise to install the pool overflow while we're having this construction done?

    thank you,
    Pool size: 18x36ft
    In-ground
    Vinyl liner

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    Re: Is pool overflow drain recommended?

    When we have a hurricane or TS wander through here, I wish I had an overflow.... rather than brave the elements (including lightning) to pump to waste....

    It is likely that the repair work you currently require is a result of overflow in past years...

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    Re: Is pool overflow drain recommended?

    I have one, and love it. I never have to worry. Now sure where you live, but as I have to close my pool for the winter, it is also nice that I never have to worry about off season overflow as well.

    My overflow does not have an open/close per say, rather it has threads, so I can manually screw in a plug if I want to close it off for whatever reason.
    IG W/Vinyl Liner Oval 18x40, 21K gal, Oval 3'-8'
    Pentair Intelliflo VS Pump, Sand Filter

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    ozdiver's Avatar
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    Re: Is pool overflow drain recommended?

    A pool overflow helps for the heavy rain scenario. It is passive (no pump) and lets you direct where the overflow ends up.
    It prevents pool water spilling over the deck into surrounding garden beds in an uncontrolled manner.

    When is comes to a hurricane, or TS all bets are off. The size of the pipe and it's passive nature cannot keep up with the volume of rainwater falling in the pool.
    My previous pool did not have an overflow, but did have a spider valve with a waste pipe. During TS Allison I actively pumped 6" out of the pool 4 times during that night to prevent overflow. There is no way a passive overflow system would have met that demand.
    That said, my new pool does have an overflow but no means to 'pump' water to waste.
    A hurricane of TS is an exceptional but expected situation in my area, I accept that in that situation I will overflow. My garden and lawn may not be so happy about that, but it is a once in 5 year event.
    Everyone has to plan for their own situation, but don't assume an overflow is a total solution.
    40k gal freeform, IG pebblesheen, 9'x'6' raised spa, 2-1/2 hp Whisperflo, 520 sq/ft cartridge, Legend w/ booster, Intellibrite 5g in pool @ spa, Rainbow 320 Chlorinator(retired),
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    Mod Squad pooldv's Avatar
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    Re: Is pool overflow drain recommended?

    Absolutely.
    There are three things that are mandatory for all my pools
    SWG
    auto-fill
    overflow

    oh, and TFP!
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    Isaac-1's Avatar
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    Re: Is pool overflow drain recommended?

    If you would fill in your location we might be able to give better advice, the big question is do you tend to get LARGE amounts of rain over short time periods?
    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
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    Re: Is pool overflow drain recommended?

    Quote Originally Posted by pooldv View Post
    Absolutely.
    There are three things that are mandatory for all my pools
    SWG
    auto-fill
    overflow

    oh, and TFP!
    Wow, I'm the exact opposite. (except for the TFP part) I removed the auto fill and overflow during remodel, and have automated liquid chlorine injection. Different strokes I guess. For the OP, I live in the desert where we get 8 inches of rain a year. The only chance I have for overflow is leaving the hose on.
    36' x 18' 20k in ground, Finest Finish grey plaster, Pentair Tagelus 100D sand filter, Hayward Northstar 2hp pump, Jandy LRZ125EN heater, spill over spa, iaqualink controlled automation, Stenner chlorination, natural rock and flagstone coping, 1" glass mosaic waterline tile, SR Smith Vortex slide.

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    Re: Is pool overflow drain recommended?

    Yes, it is very nice to have when it pours out.....
    18k: IG: Black Granite Liner: Aspen: 16x33.5: SWG: Polaris 280

    My pool build new-pool-build-in-nh-t60957.html

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    mas985's Avatar
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    Re: Is pool overflow drain recommended?

    A pool that "overflows" due to rain is no different than a slab of concrete the same size as the pool so pretty much like a driveway that gets a lot of rain. It is only the rain water that hits the pool that is actually overflowing. I don't see this as a big deal and should not cause any damage as long as there is somewhere for the water to go after it leaves the deck (i.e. drainage pipe or even grass). But the rain would hit the deck and run off anyway even with an auto drain.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Is pool overflow drain recommended?

    Quote Originally Posted by mas985 View Post
    A pool that "overflows" due to rain is no different than a slab of concrete ....
    I don't get that analogy. An overfilled pool will drain over the wall and into the area under the deck. No good can come of that...

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    ernie01jt's Avatar
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    Re: Is pool overflow drain recommended?

    You don't say what your walls are made of, while it might not hurt a concrete pool to have water run over the top. But you really don't water in between the liner and wall especially with steel walls, just my thoughts
    18' x 38' 20,500 gallon vinyl IGP, 3.5 - 7' depth, Pentair FNS Plus DE filter,
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    mas985's Avatar
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    Re: Is pool overflow drain recommended?

    Water should never run "under" the deck unless the deck is elevated. There should always be some sort of drainage around a deck to handle normal runoff from either rain or splash out even without overflow.

    But when a pool fills to the top and then starts to overflow, the amount of water that is overflowing is only the additional rain that is hitting the pool which is proportional to the pool's surface area. This is no different than if you replaced the pool with a slab of concrete. So if the pool is 500 sqft and the deck is 500 sqft, the amount of water rolling off the deck is twice what would be normally or the equivalent of rain hitting a 1000 sqft of deck. You just need to plan for that drainage.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Mod Squad pooldv's Avatar
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    Re: Is pool overflow drain recommended?

    That is true. But the skimmers overflow all the stuff in them and then the pool is full to the top and the skimmers don't work well at all.
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    ozdiver's Avatar
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    Re: Is pool overflow drain recommended?

    mas985, I totally get your point. That said, dependent on where this pool is located, it makes a big difference to how much water falls within the surface area of the pool. Down here on the Gulf coast a TS can bring 24" in 24 hrs (TS Allison). But this are exceptional circumstances. A heavy thunderstorm down here can give us 8" which is enough to overflow a lot of pools.
    If it were just water, no big difference, but we are talking either chlorinated or salt water that we might prefer in a storm drain rather than in our garden beds.

    Now, I missed the fact that this is a Vinyl Liner pool. Mine have both been plaster with concrete or paver deck.
    I have no concerns about water coming over the coping on either of them.
    Is there other negative effects with pool water coming over the coping on other pool / deck combinations?
    All pool surrounds can obviously deal with a certain amount otherwise they were not really good choices in the first place.
    40k gal freeform, IG pebblesheen, 9'x'6' raised spa, 2-1/2 hp Whisperflo, 520 sq/ft cartridge, Legend w/ booster, Intellibrite 5g in pool @ spa, Rainbow 320 Chlorinator(retired),
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    Re: Is pool overflow drain recommended?

    My builder put in an overflow and it's been great. It wouldn't be the end of the world if the water did overflow, but I don't want the crud on the deck getting back into the pool.

    The builder used a length of flex from the overflow, went under a short section of pavers and drained on the backside of the pool. I had since replaced the flex with rigid PVC and added a threaded 90 bend to the end with a short section of pipe on the end of the 90. This allows me to tilt it upwards if I want to allow the water to rise above the overflow. The length of the section that goes vertical is just long enough where the water will spill over the top of the pipe before it begins to rise on the coping. Easy and full proof way to cap off the overflow without allowing it to completely overflow.

    I usually keep the pipe in the horizontal position, allowing it to drain at the lowest position, I just turn it up in the summer months, when I want to horde more rain water. The skimmers don't work that well when it's very full.
    Gary
    21k gal SW, IG Gunite PebbleSheen, 1HP Jandy, Jandy 340 filter, Polaris 280, 17' fiberglass slide w/ 2HP pump.

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    mas985's Avatar
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    Re: Is pool overflow drain recommended?

    Quote Originally Posted by crabboy
    It wouldn't be the end of the world if the water did overflow, but I don't want the crud on the deck getting back into the pool.
    Right, that was my only point. There are a lot of other good reasons to have an overflow as was pointed out. Although the water should not run back into the pool as the deck is usually sloped away from the pool.

    But also keep in mind that given enough rain, even an overflow can get overwhelmed. A typical 3/4" overflow with the pool at 3" above the overflow (max level), would have a max flow rate of about 4.4 GPM/min. That is less than 1" of rain per hour for a 500 sqft pool. So if the rainfall exceeds that rate for a long enough period of time, the pool will overflow anyway. Of course you can use a larger overflow drain too but that would require special installation.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Is pool overflow drain recommended?

    I live in the Atlanta area. The pools has a vinyl liner. The slab is properly sloped away from the pool so that the water doesn't drain into the pool.
    Pool size: 18x36ft
    In-ground
    Vinyl liner

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