But do you know the proper slope? 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.
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.
In general plumbing practice (based on common codes such as IPC or UPC in the United States), the minimum slope for a 4-inch horizontal drainage pipe is typically 1/8 inch per foot (1%) or steeper. This slope ensures proper drainage and prevents the buildup of debris or stagnant water in the pipe.
The most important bit of obvious advice ever: soil and waste pipes need to be on a downhill gradient! The “fall” or “drop” should be between 1/40 (1cm down for every 40cm across) and 1/110. Too steep (1/10) then the water runs quicker than the solids so doesn't wash them away (ugh!).
But do you know the proper slope? 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.
Horizontal drainage piping of 3-inch diameter and less shall be installed with a fall of not less than 1/4 inch per foot. Horizontal drainage piping of more than 3 inches and up to and including 6 inches in diameter shall be installed with a fall not less than 1/8 inch per foot.
The standard slope is anywhere from ¼ inch to 3 inches per foot depending on the use. An accurate calculation is essential for properly functioning plumbing. A pipe that doesn't slope enough won't drain while a pipe that slopes too much drains water too quickly, leaving solids behind.
In general, the maximum distance of the toilet from the main drain should not exceed 4 meters, with a 2% minimum slope. Within these limits, the plumbing system can guarantee an effective draining, avoiding bad smells and the problem of emptying the siphons.
The maximum fall for a waste pipe is 1 in 40. The minimum fall is 1 in 110 (apart from vertical pipes, but that's a different story). So pipes with a gradient between 1 in 40 and 1 in 110 should have adequate flow to prevent blockages from occurring.
In short, there are cases where too much pitch on a sewer line can cause plumbing problems and issues.
The trench should be about 18 inches deep and 9 to 12 inches wide.
4″ waste line can support 90 DFU's, Toilets can be 3–4 DFU's depending on how many gallons per flush. So, 22 toilets if they use a lot of water.
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. Pipes with a diameter of 4 inches or greater can have a slope of 1/8 inch per foot downhill from the source.
The maximum longitudinal grade along the easement shall be 8%. The maximum cross slope within easement boundaries shall be 4%.
The recommended floor slope is about 2% or 2 cm per 1 meter of length. That is, if the length of the shower cabin is, for example, 1.5 meters, then the slope of the floor should be about 3 cm.
Gradients from 1 in 40 to 1 in 110 will normally give adequate flow velocities. If the gradient is steeper than 1 in 40, the liquid may run faster than the solids in the sloping foul water pipe.
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.
Since these pipes shouldn't be carrying contaminated water (stop peeing in the sink when the toilet is occupied!), the waste system doesn't need to be vented the way a soil system does, as no harmful gasses are produced.
Recommended Slope for Toilet Drain Pipes
The universally accepted standard for a toilet drain pipe slope is a quarter inch per foot of pipe (1/4 inch per foot). This means for every foot the pipe travels horizontally, it should drop in elevation by one quarter of an inch to facilitate proper flow.
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.
Re: Are 45 degree fittings allowed in horizontal drain pipe? To answer your question, yes they are allowed, but only in a horizontal configuration. You cannot use them to change elevation.
The closed sewers should not run full, otherwise the pressure will rise above or fall below the atmospheric pressure and condition of open channel flow will cease to exist. Also from consideration of ventilation sewers should not be designed to run full.
This means a 1:80 fall refers to an 80-inch rise in the horizontal plane and a 1-inch rise in the vertical plane. The resulting angle is approximately 0.7° from the horizontal. A good online tool for calculating the degree rise from a gradient ratio can be found here.
For instance, residential sewer line depth ranges from 18 to 30 inches. However, city sewer line depths are different. Your city's sewer lines must always be deeper than the deepest residential pipe to allow waste to flow downhill. As such, these lines can go as deep as needed.