What affect does the pitch of drain lines in a home or commercial building have with regards to a possible backup?
- Having the correct pitch is paramount when installing plumbing drain lines. Most people think that having more pitch is better for
a sewer drain line, this is not the case. There is a point where too much pitch can actually be the cause of back-ups. The general rule of thumb is a ¼” per foot of pitch. As you steepen the pitch the velocity of the water increases, if the pitch is too steep the water may begin to pass up the suspended solids leaving them behind. If the solids continue to be left behind you’ll have a full blown sewer back-up. Remember this “a lazy sewer is a good sewer”. You’re better off putting less pitch on the pipe so the solids remain in suspension moving slowly along and eventually discharging into the municipal sewer.