Plumbing for a Pool Bath in a Detached Garage

wamahaMay 17, 2011

We are going to have a pool built within the next week or so, and are kicking around the idea of adding facilities (toilet and sink only) to our detached garage to keep the kiddos from running back and forth thru the house (and to keep other "stuff" out of our pool!).

I am planning on having the plumber working with our pool builder handle this for us, but since I have NO idea what I am talking about, I thought I would throw this out there to see what kind of ball park I would/should expect.

Attached is a pic of the layout. As you are looking at the pic, we were hoping to put the bathroom in the back left corner of the garage. The pool equipment will be just outside of the same area (figured this would make the most since, since there will be water and probably some sort of a drain back there (again, I have NO idea what I am talking about). The garage has a concrete floor, and the area is on the raised part of the garage, so I would guess there is ~8" (4" rise + 4" floor) on concrete that needs to be punched thru.

Any guesstimates on plumbing only? I can get a cheap toilet and sink @ Home Depot, so this would be rough plumbing only.

Any help would be GREATLY appreciated!

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Some municipalities allow this and some won't. You need to contact your local codes office first to see what they say, and how much the permitting costs would be if allowed. If they're fine with the project, then the next step is to evaluate where your home's main drain is located in relationship to your desired bath location. Plumbin has to have a certain downhill slant to it in order for gravity and water to move the waste along to the sewer. That's not an internet guessable amount, nor is the location cost differences. I will tell you that an average bath remodel costs around 11K, and that doesn't involve putting in the infrastructure. With the project being planned in conjunction with a pool project where you are already doing a great deal of excavation, you might get a deal on that portion of the project, or you might no. I'm sure that you'd be talking at least that amount for the rough and final plumbing, and maybe a good deal more if you have to have extensive trenching and some sort of pump involved.

    Bookmark   May 18, 2011 at 12:02AM
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Thanks for the input. I'm pretty sure it is allowed, as I have seen it in a couple of neighbors houses. Of course, I'm assuming thier not all illegal....
Our property has a back to front slope to it now, so I'm not too worried about the pitch. As best I can tell, I'm going to have to bust thru the garage, run a different trench, come under the driveway to tap into the house main....Not exactly what I had orginally thought, but it is what it is. Our pool guy will be out tomorrow, so I'm going to talk to him about it some more.

    Bookmark   May 18, 2011 at 9:20PM
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Tapping into the sewer is going to be the most expensive part of this project unless it is very near the garage.

We are putting in a pool and had to move our utilities. In the process we ran water, gas and electric for a future garage / pool house with bath. We also had to replace the sewer and left a fitting in the ground so that we could tap into it in the future.

Find out exactly where your sewer runs through the yard. You can hire Underground detectives for a few hundred to locate, mark and video the inside of it. You can then determine if you can trench from the garage. Breaking the concrete in the garage isn't that big of deal. But if you are going to build an actual room for the sink / toilet that will be a bit more.

    Bookmark   May 20, 2011 at 10:40AM
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Yep. Talked to my pool builder today about it, and his plumbers wouldn't touch the sewer line with a ten foot pole...... The plan I had all worked out in my head is falling to pieces quickly, as I never imagined that it would be this difficult. Turns out the pool equipment is not tied to the sewer system like I thought it was. I forgot to ask him about a water line....I would assume that wouldn't be a big deal to run one back to the equipment. It would be nice to have a spout back there.

My sewer main in the front of the house, and if we put it where I want it, we are looking at about 120' of line, and we have to either tunnel under, or bust thru the driveway to get it over to the main.....Somethings are just never easy! We have tabled the project for now. May look at it again in the Spring.

    Bookmark   May 20, 2011 at 10:13PM
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Just as a point of info, to my knowledge most city codes do not allow pool drains/discharges to be tied to the city sewer. That's why your pool guys don't want to touch it.

    Bookmark   May 21, 2011 at 10:43PM
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What you have is two entirely different problems.

1.Pool Water is primarily considered clean non-potable water the same as storm drainage from your downspouts and as such it may not be discharged into the Sanitary Sewer System. It may be discharged into the surface watershed, a storm drainage ditch or into a municipal storm sewer.

2.The discharge from your proposed bathroom is sanitary waste and it must be discharged into a sanitary sewer or septic tank. It may not be disharged into the pool drain.

You could install the bathroom in your garage as proposed, but you would then have to run a sewer line from the garage to your house sewer line and tie into the house sewer line before it connects to the municipal sewer.

In order to install a bathroom in the garage you must first know what the average frost depth is for your location because the sewer line must be 6" below the average frost depth where it begins at the garage, and it must then maintain a 1/4" per foot downward pitch from there to the point where you plan to tie into the house sewer.

To give you an example let us assume for the moment that your average frost depth is 12". That means the line must be buried a minimum of 18" below grade where it begins at the garage. You are estimating a run of 120' which would require 30" of pitch so in order to tie into your house sewer the house sewer at the tiein point must be at an elevation which is a minimum of 48" below the grade at the garage location.

    Bookmark   May 24, 2011 at 12:00AM
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FYI on the pool connection to the sanitary sewer issue, that is probably a location by location issue. I know in Memphis and it's subrubs pools have the backwash / waste output tied to the sanitary sewer cleanout.

You can receive a ticket for discharging pool water to the curb in some of the suburbs. I used to replace liners and this meant waiting all day for the pool to drain vs. dropping in a 4" gas pump and droping the pool in an hour and a half.

    Bookmark   June 2, 2011 at 7:27PM
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