Scupper Width
(inches)
Scupper Width
(feet)
 Minimum flow rage
(GPM/linear foot)
Maximum flow range
(GPM/linear foot)
 6″ 0.50′ 5 15
 8″ 0.67′ 7 20
12″ 1.00′ 10 30
16″ 1.33′ 13 40
24″ 2.00′ 20 60
36″ 3.00′ 45 120
48″ 4.00′ 60 160

*Based on flow at the scupper. These ratings do not account for any system losses. System flow requirements vary per project. Account for bends and plumbing line loss.