Backwater valve installation question

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darren_t_johnson

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Hi,
I'm going to be installing a Mainline backwater valve, and the instructions say I need at least 2% grade.

I over analyze things... so does that mean the inlet pipe and outlet pipe have to have at least 2% grade, and the backwate valve should be level? The outlet pipe is already 3/4" lower then the inlet pipe.

Or should the backwater valve itself be installed on a slope? This doesn't sound right to because it the unit is slopped too much, the flap might not close properly.

Has anyone installed one before and/or offer advice?

Thanks
Darren
 

hj

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2% is the STANDARD minimum slope for a properly installed drain line. Your problem, if anything is that the inlet and outlet are 3/4' lower which creates a problem in a "straight pipe". Unless you can excavate enough pipe to make up that 3/4", you will have to install the BWV with a "backwards tilt" to make it fit.
 

darren_t_johnson

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Hi hj,
yes, 2% is the "1/4inch per foot" minimum that is required. I'm digging up a lot, and have more then enough room to make up that 3/4" difference.

My main concern was that should the Mainline backwater valve unit itself be level, and the inlet and outlet pipes should have the 2% minimum grade.
Or is the backwater value supposed be tilted so that the 2% grade is consistent across the valve unit. The instructions for the valve are vague about this, and I haven't gotten any feedback from the Mainline website.

NEVERMIND.

I was just typing my response and realized that the 3/4" difference is more than the required 2% grade... for some reason I thought it was not.... so the 2% grade minimum is referring to the inlet and outlet pipe.

sometimes it helps to talk/type it out...

Thanks, and sorry for posting a pointless question.
 
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