When running a sewer pipe how many inches of fall do you need??
Question:3 inch sewer pipe, 10 foot sections
Answers:
If you are doing it in a community then the good amound would be approximately 9"
About 1/8" per ft.
1/4" per foot.
1/4" per foot. You can obtain an OK from your inspector to run it at 1/8" foot if you prefer.
For a three inch sewer line, you want to give it a 1/4 inch fall per foot. 1/8 inch fall per foot at the very least. You don't want to give it too much fall because, the water will outrun the solids leaving the solids behind, therefore having a possibility of clogging your drains later on. Good luck.
Slope = Rise / Run
Slope = Y / X // which means:
.. . . . for every increase in X it goes upward by an amount of Y. This is the slope angle.
Example : Slope = 1/2
// for every increase in length by two units, it raises upward by one unit.
A 10 foot section is not an awefull lot, so truthfully if it were raised by a difference of about 2 inches over that length I think that would be good for water flow.
This is to say, for every increase in length by a factor of 60 inches it will rise by a factor of 1 one inch
run .. .. rise
120 .. .. 2
60 .. . .1
30 .. . . (.50)
15 .. . . (.25)
3 .. . . (.05) (too small to measure)
--------All Measurements In Inches----------
so this means, for every 15 inches you will rise by 1/4 inch. This will give you a total of a 2 inch slope over the 10 feet.
The 1/4 inch rise is 1/4 inch from the last rise, or the starting point if its the first point.
If you were to go with the 1/8 inch someone suggested that means for every 12 inches in length you will rise 1/8 of an inch. Over 10 feet that will give you a rise of
(in inches)
12 .. .. 1/8
120 .. ..1.25 inch rise
// this is close to a straight pipe. This may not be sufficient in all cases - it may block - up often.
12 ... ... 1/4
120 .. .. 2.5 inches // seems OK to me also.
9 inches suggested...let's see
Find two points...
rise / run
9 / 120
4.5/60
m = (9-4.5) / (120 - 60 )
m = 4.5 / 60
m = 1.125 /15
// this means to get a 9 inch rise on the pipe over 10 feet you will have to have a rise of 1 1/8 inch per 15 inch run. Seems extreme again.
BTW: I think, if the slope on the pipe were too steep, I don't think it is a matter that the water will flow too fast and leave the solids behind and block- up later on. I think, its the opposite - the solids would fall too fast blocking the pipe if there is so much the pipe can't handle it. I say this because it is all based on gravity - which is greater on the larger mass. The solids will fall at a greater rate than the liquids will flow. The solids would pile up at the bottom of the pipe - blocking it.
Again, this is just my thoughts on the entire topic...hope all this helps ya.
Kinda much huh?
( Hmm..somebody had too much coffee)
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