Gutter Drains in negative edge pool / how many


In The Industry
Nov 10, 2020
Good day and I will appreciate your help a lot.
We engineer a vanishing edge pool with wet wall effect. Is is just decirative pool, not for swimming, just 2,5 m3 water volume. And weir flow rate is apprx 11,8 m3 per hour. Weir length is about 11 meters long.
The concrete gutter is planned all along the length of weir.
The Question is _ how many gutter drains should be planned and drains diameter.
Our engineer insists that one drain of 2-1/2 " diameter is enough, considering the slope. But how 3,3 liters per second can pass through this?
According to my calculations we need at least 2 drains with diameter of 3" each.
But he says it is too much for such a small pool and wet wall effect.

Your help will be highly appreciated.



In The Industry
Nov 10, 2020
Good day and thanks in advance for your participation!
We are engineering the negative edge pool with water overflowing the weir. Small pool is just for decorative purpose with size of L 11 m, D 0.5m and W 0.5m.
The waterfall effect is just wet wall. And wier length all along one wall with wier flow rate =11.8 m3.
The gutter is planned along the length of wier.
The question is How many drains and diameter of drains should be here in the gutter?
Our engineer insists on 1 drain with diameter 63mm (2") with slope of gutter. But how it might be enough to pass through 3.3 liter per second even with slope?
I insist that minimum 2 drains should be with diameter 2-1/2 ". But he says it is too much for such a small pool and wet wall effect.
The gutter cross section size: 100x 180mm.
Gutter is just for water transit.
For water surge we use balance tank additionally.
Will appeeciate your help!


Gold Supporter
TFP Guide
Nov 12, 2017
Central California
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Not sure why all your spec's are metric... but if the calculator I found is right, that's over 3000 gallons. But you need a "per" to convey flow, so what is the time factor? As in 11.8M3 per minute/hour/day? If per hour, which would match your 3.3 liter per socond spec, that's about 50GPM (gallons per minute), which I believe a 2" pipe is more than capable to carry.

Distance is also a factor, so how far does that pipe travel? With those two spec's clarified, I think our builder experts could better weigh in...


In The Industry
Nov 10, 2020
Dirk, thanks a lot for your response.
Yes, I am sorry not to specify esrlier.
1. Wier flow rate is 11m3 per hour.
2. The pipe will travel for apprx. 10 meter distance.

As for pipe it will handle. I just curiouse whether it should be more than one drain in the gutter/ trough itself, not leading to gutter overflowing?

The gutter length is 10meters long and I think that one drain hole in it is not enough?


In The Industry
Nov 10, 2020
Good evening and I will appreciate your help and advice reg right circulation pump selection.
We are engineering infinity pool outdoors with glass front wall, just for decor purposes, not for swimming.
Pool basin volume: 2,5 m3.
Weir length: 11 meters.
Weir head crest/ glass wall width: 0,5 meters.
Waterfall effect: just wet glass , with water sheet = 3 mm.
Weir flow rate: 11,8 m3/hour.
Plumbing trass/ route: appr. 8 meters, 4 meter vertical and 4 meter horizontal .

The qystion is whether 13 m3/hour pump will be enough, not to lose water head at the below glass?

Thanks in advance,