Where the HECK is my sewer line?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by JLM34, Nov 28, 2011.

  1. JLM34

    JLM34 New Member

    Messages:
    16
    Location:
    TX
    I'm trying to find the sewer line where it exits the house (on slab). I know exactly where it meets the city sewer down by the street, which is also pretty much in line with the vent pipe coming out of the roof. I have a sink in the western most half of the bathroom. It connects to the vent pipe in the wall about a foot to the right. The vent pipe is also right in line with the tub drain, which is directly south about 4 feet from where the vent pipe is vertically. The toilet is about 2-3 feet right of the sink/vent pipe connection. Common sense tells me the toilet probably drains west right into the vent pipe and it and the sink then flow directly south, meeting up with tub drain, and straight out the front of the house. This is not the shortest route to exit the house, as it has to pass under a bedroom. The shortest route would be to exit the house to the east, but it doesn't seem that that is where it's going. I've dug about 3.5 feet around where I was almost certain the pipe had to be - can't find it.

    How deep is the pipe typically buried where it exits the house?? Now - from my house to the street is a pretty decent fall - I'm guessing 4-5 feet fall over about 50-60 feet. I'm guessing if they stuck with the 1" per 10 ft pitch from the house to street, then that would require the pipe to be buried pretty dang deep at the house. So - does the depth that the pipe is buried where it exits the house vary from house to house or is there a pretty standard depth they stick with? I think I'm in the right area, but I just hate to keep digging and digging not knowing how deep to go.

    There's no cleanouts whatsoever - I've looked everywhere.
  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Forget any thought that they would have used a certain pitch, or any 'standard' installation. They just make sure it has slope. For one thing, the pitch is 1/4" per foot, and some areas allow 1/8" per foot on 4" or larger pipe. That means minimum pitch 1.25 or 2.5 inch per 10 feet. They may exit the house shallow, proceed at minimum pitch towards the street, then drop near-vertical if necessary to the main, which is probably at least 10' deep and in the middle of the road. Or they may have started deeper at the house and used a trench with a modest slope from there to the main. Or whatever!

    A plumber with a camera and a locator may be able to narrow it down for you.
  3. JLM34

    JLM34 New Member

    Messages:
    16
    Location:
    TX
    Something tells me they started pretty darn deep at the house. Basically I need to tie in a new line into the main one. I'm about there and everything seems to have good pitch and is flowing well. A 5-6 foot dig is not sounding too great. I'm at 2-2.5 feet now, which is fine and plenty below the frost line here. Here's what I have though - the light bulb came on, which might or might not be a good thing with me. I have a gray colored PVC - 4" I believe that runs from very close to where I was planning to tie in at close to the house, all the way to the street. It's a storm drain that collects gutter water and empties it curbside. It's probably fairly unnecessary given the lay of the land. I could live without putting storm water in it. It also happens to run about 4 feet parallel from where I know the main sewer line is and I could get to easily without digging to China. Why couldn't I disconnect the storm water collection box, tie into it with my new line at the house, then go down towards the street, cut the pipe and connect to the main line with a sweeping elbow? I know it was put in as a storm drain, but it seems the pipe would work just fine. Thoughts?
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,293
    Location:
    Cave Creek, Arizona
    sewer

    The sewer line runs HOWEVER the plumber decided to dig the ditch that day. There is no "standard" way he would have done. Although in most cases it WOULD be in a fairly straight line from the vent to the city connection. Most plumbers are lazy whenever they can be so the sewer probably comes out of the house about 30" to 36" deep, and there IS a cleanout. Either it, (they), is buried under the grass, or it is a tapped tee in the sewer line about 30" from the house and you have to dig down to use it. As far as the depth were it connects to the city stub, it could be as deep as the sewer in the street is.
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