Horizontal drain piping, including building drains and building sewers, shall be installed in uniform alignment at the following uniform slopes: not less than 1/4 inch per foot for 1-1/4 inch. 1-1/2 inch and 2 inch pipe size. not less than 1/8 inch per foot for 3 inch, 4 inch, 5 inch, and 6 inch pipe size.
While you can indeed run a horizontal vent pipe, you can't do it indefinitely; this is designed to provide your pipes with the ability to drain into the sewer system. The typical rule of thumb according to code requires you to run a horizontal pipe for no more than one-third of the total length.
If you've ever wondered what the minimum slope for water drainage is, it is generally accepted that 1/4″ per foot of pipe run is the minimum for proper pitch on a sewer line.
As a general rule, the recommended slope for most plumbing pipes is 1/4 inch vertical drop over every 1 horizontal foot, or about 2 percent.
Two-percent slope is required for 21/2-inch (64 mm) diameter and smaller pipe, and 1-percent slope is required for 3-inch (76 mm) diameter and larger pipe. Drainage pipe can always be installed with greater slopes.
Horizontal drain piping, including building drains and building sewers, shall be installed in uniform alignment at the following uniform slopes: not less than 1/4 inch per foot for 1-1/4 inch. 1-1/2 inch and 2 inch pipe size. not less than 1/8 inch per foot for 3 inch, 4 inch, 5 inch, and 6 inch pipe size.
1. The pipe slope drain shall have a slope of 3 percent or steeper. 2. The top of the earth dike over the inlet pipe, and those dikes carrying water to the pipe, shall be at least one (1) foot higher at all points than the top of the inlet pipe.
Horizontal drainage piping shall be installed in uniform alignment at uniform slopes not less than 1/4 unit vertical in 12 units horizontal (2-percent slope) for 21/2-inch (64 mm) diameter and less, and not less than 1/8 unit vertical in 12 units horizontal (1-percent slope) for diameters of 3 inches (76 mm) or more.
Sanitary tees may be used for horizontal drainage flow through the run of the tee where the branch of the tee is for venting only and is oriented within 45 degrees (0.79 rad) of the vertical. A sanitary tee can be installed on its back for venting applications in sanitary drainage.
1 through 917.4. 3. Water closet connections shall be not greater than 4 feet (1219 mm) in developed length measured horizontally from the stack. Exception: Where the connection is made with a sanitary tee, the maximum developed length shall be 8 feet (2438 mm).
The ideal slope of any drain line is ¼ inch per foot of pipe. In other words, for every foot the pipe travels horizontally, it should be dropping ¼ inch vertically. Many drains either have too little slope or too much slope. That's right, it is possible to have too much slope in your drain lines.
Use Slopes to Achieve Optimal Drainage Conditions
According to the EPA, patio slabs, walks and driveways need a minimum slope of 1/4 inch per foot away from the house with back-fill to prevent settling. The final grade must be sloped away from the foundation by 1/2 inch per foot over a minimum distance of 10 feet.
For less than 1l/s, a fall of 1:40 (25mm per metre) is appropriate. For discharge from any WC, a fall of 1:80 (12.5mm per metre) is recommended. Gullies for foul water drainage must feature a 50mm water seal at minimum.
A gradient of 1:60 means that there will be 1 unit of fall for every 60 units of patio width. The patio is to be 4.2m wide, so if that distance (the run) is divided by 60, the result is the 1 unit of fall. We'll work in millimetres rather than metres... So, there needs to be 70mm of fall across the patio.
The slope of a horizontal drainage pipe shall be not less than that indicated in Table 704.1 except that where the drainage piping is upstream of a grease interceptor, the slope of the piping shall be not less than 1/4 inch per foot (2-percent slope). For SI: 1 inch = 25.4 mm, 1 inch per foot = 83.33 mm/m.
The minimum sizes of vertical, horizontal, or both drainage piping shall be determined from the total of fixture units connected thereto, and additionally, in the case of vertical drainage pipes, in accordance with their length.
Multiply the length of the pipe (x) by the inches needed to slope the line (y) This equals height difference (z) between the beginning and end of the pipe (x) ⋅ (y)=(z) Example: If your pipe is 10 feet, and it needs to slope ½ an inch per foot, the equation would be 10 ⋅ ½ = 5 inches.
The minimum desirable physical slope shall be 0.5 percent or the slope that will produce a velocity of 3.0 feet per second when the storm drain is flowing full, whichever is greater. Systems should generally be designed for non pressure conditions.
For drains, the top of drain shall be slightly less than the existing concrete floor, and should allow for 1/4 inch per foot slope around the new drain.
Six metres is the maximum run according to Building Regualtions, but as you have realised yourself, a good fall on the branch pipe is essential. 2.5º, or 44mm fall for every metre run, is the usual standard. IIRC it is permissible (but inadvisable) to go as low as 18mm per metre, the maximum is 90mm per metre.
The horizontal combination drain and vent pipe shall have a maximum slope of one-half unit vertical in 12 units horizontal (4-percent slope).
UK building codes require downpipes to exit a metre from foundations to avoid saturated soil that could undermine structures. Surface drains and soakaways are best as they slowly absorb water, unlike sewers which risk flooding if pipes discharge directly into them as this can overwhelm the drain system.