Recommended sewer slope for low flow toilet

Installation is for a flushometer equiped wall mount Amer. Std. "Afwall" toilets on a 4" drain line. What is the minimum recommend slope for the 4" CI sewer?

Code indicates I can install 180 DFUs on a 4" at 1/8 slope, but with low flow toilet will the solids carry through?

All opinions welcome, even the bad ones!

Proper slope for drains is 1/4" or more per foot.

I think I've also read that beginning at 4" pipe, you can get by with a lower slope. I dont' think you'd have a problem with a low-flow toilet. The older ones used more water more to build up the velocity and head pressure than to float things away. The successful low-flow jobs flush MUCH faster than the old once, so it manages well. An older technology toilet would dump most of the tank into the bowl, and only after filling it up would it reach the point when it would dump out. The new ones hardly fill the bowl much at all, and use techniques like a siphon jet and basically shoot it out using larger diameter passageways.

Gary Swart said:

Proper slope for drains is 1/4" or more per foot.

Click to expand...

OK, I was told it was 1/4"/foot, not or more... the reason given was with too much of a slope, the liquids out run the solids. I did my entire house at 1/4" and if I needed more I did a vertical drop. So what's the story?

Rancher

low flow flush carry through

I normally agree with the 2% or 1/4 per foot slope.

This is a siphon jet with flushometer valve, so initial vgelocity and flow is not a concern. However, length is 90-100 feet before I get to a spot where I can use the 1/4" slope. What is the opinion on a flush carrying things the initial distance?

The question of more slope was mentioned the other day. This appears to be an old wives tale. The example used as an illustration was a multi story building. If you're really doubtful, go back and find that post. It was just a few days ago.

OK, went back and read all if it, I understand the multi-story building part of it, but where did this 1/4" a foot wives tail come from? What does the UPC say?

Rancher

The old wives tale comment referred to the idea that you can have too much slope. The 1/4" per foot is the minimum slope, there is no maximum.

slope

4" lines can usually be installed with an 1/8" slope, and 6" ones with a 1/16".