I would like hot and cold water and toilet in my garage which is 15 yards behind the house. I need to connect to the house's drain pipe. How do I deal with the drain pipe to prevent freezing while maintaining the proper slope.

It has to be below the frost line as set by the building inspector for your town, and if the slope is a problem, you'll need a pump. Be sure zoning allows this too.

Joy pretty much nailed it. You will run a 4" service from your garage main to the house. The slope from the garage will about 11 1/4"
If you go 1/4" to the foot or about 5 1/2" if you use 1/8" to the foot. The water lines will set in the same trench on a shelf a foot or so away from then sewer line. (check wityh your local building department). Since your house sewer is already under the frost line freezing should not be a concern. Good luck, Tom

Now we can start talking about how you will keep your supply line from freezing too. Have you though much about that? Will the garage have its own water heater or are you taping into the domestic service?

Hi,

If your running waters 15 yards away and water lines are prone to freezing, I would recommend minimum depth of 3' of earth coverage. I have worked in freezing and snowy climates. Or consult with building inspector. I would also recommend heat tape around your water lines coming out of the ground into your garage and use thermal insulation around the heat tape as well.

Sewer lines are to be a minimum 1' below finish grade according to plumbing code.

I addressed the water lines in post#3,

Quote:

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The water lines will set in the same trench on a shelf a foot or so away from the sewer line. (check wityh your local building department). Since your house sewer is already under the frost line freezing should not be a concern.

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regards, Tom

kidsunshine,

It is argaiu1017 once again, I forgot to mention that if you decide to pull a permit for the garage project that having water service in the same trench as the sewer will be permitted only if:
1: sewer pipe is approved for use within a building. Then you will not need a 12" shelve or separation between water pipe and sewer.

For example, if you are using PVC DWV or ABS then both water and sewer pipe can be in the same trench because both drain pipes are allowed to be installed underfloor or slab of a dwelling.

Assuming that Kidsunshgines house sewer is installed beneath the frost line he will tie the garage main back into the house main.
My code, (SPC) Chapter 12, Section, 1206.4 (a)and (b) allows you to install water lines as I've stated in post#3. Since the sewer is beneath the frost line the water should be just fine.
Good luck, Tom

kidsunshine,

Can you tell us you lacation(roughly). As codes vary greatly from area to area. As an example, in my area, our code mandates water must have a bury of 7 foot min, and sewer four foot min.

Yep, it gets pretty cold here.