Angles, slope key in plumbing
It’s like Christmas when I get to open readers’ questions, and the photos that often come with the inquiries are like eye candy for me. (My wife thinks I’m nuts!)
A man named Wayne reached out from Houston. He had decided to do some serious DIY plumbing at his house, and as he put it, “I’ve racked my brain and can’t come up with a code-approved way to make this happen.”
I’ve been a master plumber since age 29. I’m not going to transform you into one in this column, but I’d like to share some pointers, either if you try to do what Wayne is or if you’re checking the work of a plumber.
Transporting wastewater from your home to a city sewer or septic tank is serious business.
The drain and vent pipes in your home should mimic Mother Nature. Look at how creeks, streams and rivers work. Small streams eventually connect with larger rivers. When they intersect, the angle is rarely a hard 90-degree turn; it’s more often a gentle angle.
You should design your wastewater pipes similarly, for the most part. It’s bad plumbing practice to have a hard 90-degree bend in a horizontal drain line that’s buried in a slab or otherwise hidden. If you have to make a 90-degree bend, use two 45-degree fittings and put a small piece of straight pipe between.
It’s fine to have a larger-radius (sweep) 90-degree bend at the base of a vertical drainage stack where the wastewater starts to travel horizontally. It’s also a good idea to have a sweep 90-degree fitting where a drain pipe pops out of a wall for a kitchen, vanity or laundry sink.
Drain-cleaning snakes can navigate around these sweep-90 bends, but they may drill through a plastic hard-90-degree fitting by mistake. (You can use those hard 90s in the vent pipes that supply the plumbing system with air.)
And don’t forget about pipe slope. Use gravity’s force to get your solid and liquid waste out of your home. All drain lines should have a minimum fall of
inch per foot of horizontal run.
If you slope the pipe much more, you can set yourself up for future clogs, as liquids may outrun the solids in steep-pitched pipes.