Overflow drain too low and slow

newpoolj

Well-known member
Oct 15, 2020
71
Sacramento, Ca
I had a pool built this spring that, among other problems, has the auto-fill/overflow canister installed too low. This meant that water would drain out of the overflow when it shouldn't. The type of overflow canister I have is something like this.

The pool builder's solution was so shove a filed down 90 degree sprinkler fitting into the outlet, to slightly raise the height of the outlet drain (see attached picture). Aside from this being pretty weak - the fitting later fell out causing a lot of water to drain out of my pool during the summer - it decreases what is already a pretty narrow 1/2" outlet, limiting the volume of the overflow.

Two questions I have:
- Is it common for these kind of narrow overflow drains to not be able to keep up during heavy rainfall? We're getting a ton of rain here the last day or two and the pool is slowly filling up, even with the overflow.
- Can anyone recommend a better fitting for raising the overflow inlet level?

Thanks
 

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mknauss

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You would be better off to plug that hole and get a submersible pump to drain water when needed. Those overflow will not keep up with heavy rain. In the South, they install proper overflows. Here in the west, we rarely need them so a pump is better to use.

You can get a submersible pump for under $100 from Amazon or Harbor Freight.
 

newpoolj

Well-known member
Oct 15, 2020
71
Sacramento, Ca
You would be better off to plug that hole and get a submersible pump to drain water when needed. Those overflow will not keep up with heavy rain. In the South, they install proper overflows. Here in the west, we rarely need them so a pump is better to use.
That's good to know! I'm curious though, what does a proper overflow look like?

You can get a submersible pump for under $100 from Amazon or Harbor Freight.
I do happen to have a pump, I just wasn't sure if I should use it or if the overflow should be adequate. I also have a hose bib after my pool pump that I think I can use to drain the pool some. Is there a recommendation for when to use it or how low to lower the water?
 

mknauss

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May 3, 2014
44,928
Laughlin, NV
Pool Size
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Salt Water Generator
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Pentair Intellichlor IC-40
That's good to know! I'm curious though, what does a proper overflow look like?
They are a drain installed normally in the skimmer throat with a grate over it. Uses 1.5" line or larger to flow to the drain point.

Is there a recommendation for when to use it or how low to lower the water?
If your pool is gunite, just do not let it overflow the coping. It can pull in debris from your yard.

Best to NOT use the hose bib if at all possible. Using a $1000++ pump to do the job of a $70 one is not a good idea.
 
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newpoolj

Well-known member
Oct 15, 2020
71
Sacramento, Ca
They are a drain installed normally in the skimmer throat with a grate over it. Uses 1.5" line or larger to flow to the drain point.


If your pool is gunite, just do not let it overflow the coping. It can pull in debris from your yard.

Best to NOT use the hose bib if at all possible. Using a $1000++ pump to do the job of a $70 one is not a good idea.
Thanks for the info. Is there any risk/problem that could be caused if water gets above the tile line and seeps under the pool coping/decking (mine is combined concrete)?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
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Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Unless the pool was built on fill or on a hill, the biggest threat to water going above the coping is debris washing into the pool.

If you have no other way to lower the pool level, use the hose bib. Just watch it.
 
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jmastron

LifeTime Supporter
Jul 21, 2014
345
Sacramento, CA
Bear in mind that this storm was very extreme -- 5.4 inches of rain in 24 hours (any 24 hours) broke a record set in 1880. More than 4 inches has only happened twice since then; much more normal is 1-2" on the heaviest days. So if the level was slowly rising yesterday but never in danger of overflowing, I suspect the drain size is adequate for this region.

I started to do the calculations of gallons per minute and pipe size -- for example, for my pool's surface area 5" of rain in 24 hours is 2000 gallons/day or 1.4 gallons/minute, although the peak yesterday was probably double that. I agree that places that can get 6-8-10" of rain in a day over multiple days need a much bigger drain!
 
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newpoolj

Well-known member
Oct 15, 2020
71
Sacramento, Ca
Bear in mind that this storm was very extreme -- 5.4 inches of rain in 24 hours (any 24 hours) broke a record set in 1880. More than 4 inches has only happened twice since then; much more normal is 1-2" on the heaviest days. So if the level was slowly rising yesterday but never in danger of overflowing, I suspect the drain size is adequate for this region.

I started to do the calculations of gallons per minute and pipe size -- for example, for my pool's surface area 5" of rain in 24 hours is 2000 gallons/day or 1.4 gallons/minute, although the peak yesterday was probably double that. I agree that places that can get 6-8-10" of rain in a day over multiple days need a much bigger drain!
Thanks - now I just need to figure out a better fitting since the one the PB rigged up doesn't stay put.
 
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