I have a piece of property that has an existing mobile home on it. I'm having a new mobile home moved onto it this weekend for my mother-in-law. The property has public water and sewer. I am going to be running water and sewer lines for the new home from new taps that the utility company will install. It's approximately 100 feet from the road (where I assume the taps will be installed) to where the home will be located. Do I have to just dig a trench and lay the pipes in it? Can both pipes use the same trench? If so, should they be separated somehow or can they just lie alongside each other? Does the sewer line have to be completely straight or can I use elbows in it if I need to? What should the drop be for the sewer drain? I’ve read on another post on this board that ¼” per foot is appropriate? Is this correct? How far underground should the pipes be run? Is there any way to locate any of the existing pipes that are underground so I don’t run the trencher through them? Sorry for all the questions. I’ve done just about every kind of repair or remodeling that can be done to a house, but this is a new area for me.

"Can both pipes use the same trench? If so, should they be separated somehow or can they just lie alongside each other?"

Section 1206.3 of The Standard Plumbing Code states, under." Service Lines Near Drains or Sewer Lines" states: Except as permitted in Section 1206.4 the underground water service pipe and the building drain or sewer shall not be less then 5-feet apart horizontally and shall be separated by undisturbed or compacted earth. Section 1206.4 states under "Permitted Installation of Water Service near Drain or Sewer Line" that The watrer service pipe may be placed in the same trench providing the following conditions are met.
(a) The water service, at all points, shall be at least 12inches above the sewer line at its hightest point. --or--
(b) The water service shall be placed on a solid shelf excavated at one side of the common trench.

"Does the sewer line have to be completely straight or can I use elbows in it if I need to?"
You may not use quarter bends but may use short or long sweeps to make a turn. The less bends the better.

"I've read on another post on this board that ¼” per foot is appropriate? Is this correct?"
This is correct, however if slope in tight you may drop to 1/8th inch per foot.

"How far underground should the pipes be run?"
It will depend on where the sewer leaves the house.

"Is there any way to locate any of the existing pipes that are underground so I don't run the trencher through them?
What pipes are you worried about? You're replacing the old pipes so trenching through them, if that should happen, shouldn't make any difference.

Good luck, Tom

"Is there any way to locate any of the existing pipes that are underground so I don’t run the trencher through them?
What pipes are you worried about? You're replacing the old pipes so trenching through them, if that should happen, shouldn't make any difference.

Good luck, Tom

Thanks for your help. The existing pies that I'm referring to are the ones that are supplying my existing house. These pipes will remain in place since they'll still be used. That's why I want to make sure I don't trench through them. Is there any way to locate them so I don't tear through them?

"The existing pies that I'm referring to are the ones that are supplying my existing house. These pipes will remain in place since they'll still be used. That's why I want to make sure I don't trench through them. Is there any way to locate them so I dont tear through them?"

Not unless you made a diagram when they went in. If you can establish where they leave the house and where they connect to the street you have some idea of where to be cautious. We try to make our sewer and water runs as straight as possible. Good luck, Tom

That's what I was afraid of. They were put in long before I came along. Thanks again for your help. I appreciate it.

Call 811 and all your utility suppliers will come out and mark the lines for you for free.

As far as how deep the pipe should be buried, OK, the height of the bottom of the pipe where it exits into the main sewer is predefined, it is what it is. The other end, the inlet end, of your drain pipe needs to be high enough to allow you 1/8" of drop for 1 ft of pipe, or 1" of drop per 8 foot, or 12.5" drop per 100' of line. I would personally keep the home end as high as i could, probably a couple inches under the ground where it exits out the underpinning. It all depends on how deep your main is. If you can easily get the 12 and a quarter inches of drop, you may bury it a little deeper. Most importantly though, use 6" pipe,
Put yourself an add on Craigslist.com 6" sewer pipe wanted. People have left overs all the time. I just purchased 130 feet of 6", a 6"T, a 6"4"T, 3 45s,all for $100. Could have took more. Would have been over $500 at Lowe's or HD.
Good Luck

To locate your existing pipes if calling 811 doesn't work. Go under the house and determine where the water main line exits the home. Measure from the nearest wall then go outside and measure to find the spot. Stand there and look towards your water meter at the road, That, more than likely, is the route the line was lain. If they laid it in any direction other than straight towards the meter, there must be a reason, such as a big tree, building, or something you would have to go around.

Hi Wigtall,
We appreciate your imput. Thaqnks. However, you're responding to a 4 year old dead thread. Look in the upper left hand corner for the dates.
Welcome to The Plumbing Page. Tom