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.
Pitch on a house drain
The general rule is 1/4″ of pitch per foot of run. However, some other issues do come into play. An extreme amount of pitch can cause the wastewater inside the drain to flow extremely fast.
If the slope is not steep enough, the sewage slows down, resulting in clogs. If it's too steep, water and solids can separate, causing solids to accumulate in the pipe.
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.
The maximum longitudinal grade along the easement shall be 8%. The maximum cross slope within easement boundaries shall be 4%.
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 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!).
a 1 in 40 drop is 25mm drop in a 1 metre run. To measure that, I have a standard 1 metre long level, and I tape a small bit of 2*1 timber to one end of the level, then set the pipe so the level reads level and you have a 1 in 40 fall.
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.
Most older homes have sewer lines that are made of clay drain pipe. These materials generally have a lifespan of 50 years, though many last much longer. Over time, they are subject to stress from freeze and thaw cycles, and intrusion by roots from nearby trees that can cause them to crack and eventually collapse.
General. 1) Sewer lines shall be laid on a straight alignment and uniform slope between consecutive manholes. 2) Horizontal and vertical curves in sanitary sewers are not permitted.
Vertical is fine. 45 to 90 degrees (vertical) is fine. DWV lines that are close to horizontal should be sloped 1% to 2% (1/8″ to 1/4″ drop per foot) towards sewer/septic for both drain and for vent lines. So between 2% and 100% (45 degrees) is too steep (and also not steep enough).
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.
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.
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.
Basically: Soil Pipes are designed to transport the soiled water (blackwater) from your toilet, urinal, or bidet (if you're fancy). Waste Pipes are designed to transport the wastewater (greywater) from your sinks, shower, bath, washing machine, or dishwasher.
To calculate drainage fall, divide the total length by the fall ratio. For a 1 in 40 fall, divide the length of the pipe by 40.
What does a 45-Degree Angle Look Like? 45-degree angle looks like a greater than (>) sign or lesser than sign (<). If we draw an angle bisector to a 90-degree angle, the small angles thus formed will be 45-degree angles. It also looks like the open face of scissors.
Pipes must slope slightly downhill to drain properly. 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.