Originally Posted by gunit
Does this sound reasonable?
Turns out the 2011 NEC is on the Web because once it becomes law it is no longer covered by copyright. I also have an online version of the 2008 NEC.
Therefore, a current edition of the International Residential Code is probably on the Web somewhere, and I recommend you look for it.
I had a simple vanity install and had very few options as to piping if I would follow their guidelines if I didn't want to tear up the wall and repipe.
These codes can be pretty restrictive.
However, as to testing, for testing a lavatory sink you can fill it to the overflow hole (about a gallon) and yank out the stopper at time = 0. Then, good systems drain in 5 to 15 seconds (sample size = 2) and a bad one (sample size = 1) in 70 seconds. Even if you see a little whirlpool the piping can still be partially restricted.
For more accuracy/repeatability fill with 1.0 gallon.
For larger sinks some benchmarks can also be extracted, probably using two or more gallons, with a Disposall running or not.
Stay tuned to this channel!