The Ontario Building Code | Hydraulic Loads to Soil or Waste Pipes
7.4.10.6. Hydraulic Loads to soil or Waste pipes
(1) Except as provided in Sentence (2), the hydraulic load that is drained to every soil or waste stack shall conform to Table 7.4.10.6.
Table 7.4.10.6.
Maximum Permitted Hydraulic Load Drained to soil or Waste Stack
Forming Part of Sentence 7.4.10.6.(1)
| Item | Column 1 pipe Size, in. | Column 2 Maximum Hydraulic Load, fixture units | Column 3 Maximum Fixture Units Drained from any one Storey |
| 1. | 1 ¼ | 2 | 2 |
| 2. | 1 ½ | 8 | 5 |
| 3. | 2 | 24 | 10 |
| 4. | 3 | 102 | 18 |
| 5. | 4 | 540 | 100 |
| 6. | 5 | 1 400 | 250 |
| 7. | 6 | 2 900 | 500 |
| 8. | 8 | 7 600 | 830 |
| 9. | 10 | 15 000 | 2 700 |
| 10. | 12 | 26 000 | 4 680 |
| 11. | 15 | 50 000 | 9 000 |
(2) Where the nominally horizontal offset in a soil or waste stackis 1 500 mm or more, the hydraulic load that is served by it shall conform to Table 7.4.10.8.
(3) Vertical sanitary drainage pipe shall be designed to carry no more than 29% of its full capacity.
In Plain Language
Except as provided elsewhere, this article sets the maximum hydraulic load, in fixture units, that different sizes of soil or waste pipe can carry, forming a key part of drainage pipe sizing.
This is a plain-language summary of the 2012/2017 Ontario Building Code text above, for general understanding only and not a substitute for the Code. Always confirm current requirements against the 2024 edition (O.Reg. 163/24) or a qualified professional before construction.