Slope and size....

Old 11-04-06, 08:08 AM
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Join Date: Dec 2001
Location: Volusia County, Florida (Central)
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Slope and size....


having to relocate the pipes from a detached garage bathroom which is currently a 3" pipe, right or wrong.

I know the slope for a 4" pipe is 1/8" per foot and a 3" is 1/4" per foot (code in Volusia County, Florida) according to a plumber we chance met in home depot.

Now that I've dug it at the garage and planned the new route, would like to bury it deep as possible and can meet code with either measured slope (1/4 or 1/8).

My question is: Can I slope a 3" pipe at 1/8" also? Don't know whether that is minimum code numbers or maximum.

Would you use a bushing to increase the 3" to a 4" pipe for the 78' length to the new tap for any reason? Actually, thinking of doing that just to bury the pipe deeper.

Thanks for any help,

Old 11-04-06, 03:26 PM
Join Date: Nov 2004
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In general, you would never be allowed to REDUCE the size of a waste pipe. So, if you increased to 4" at the bathroom, that can never reduce back down to connect to any 3"

The slopes mentioned are minimums. General requirement it 1/4" per foot, but many local codes will allow 1/8" for 4". As far as I know, 3" would always require 1/4".

Slope is much more important than you may think. Water goes downhill!. Leave a flat section in the pipe, and the water and waste will sit there. They count on the flow of the water to scour the pipe, carry the waste. Without slope, your flat sections would quickly clog.

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