Help with plumbing for ADU

[RamJacCorp]

I have a 60's rancher with 1 bathroom. Looking to add a small ADU for a relative in the back yard. I originally thought I could just have a trench dug on the side of the property and tie into the sewer line in the front yard, but the distance would be too far to get the necessary pitch. The only access to sewer is the line under the toilet, which is near the outside-facing brick wall in the back of the house. On the other side of the wall is a concrete patio, which goes about 10 feet from the wall to the lawn. Water lines are underground, so I'd likely have to remove the vanity and tie into them below ground level, running them out next to the sewer pipe. Is there any way to pull this off with it costing a small fortune? Can sewer and water lines be run under the concrete patio, or would the patio have to be broken up? Any idea what kind of plumbing contractor costs I'd be looking at? Thanks for any help you can offer.

 

[Rossando]

Maybe sump pump pit for sewer system that will have to tie into yours but it would be nice to have a separate line that ties in outside your house. It makes sense to run this pipe outside or even create this system between you and them to get the best grade.
Water Lines can just be 1 cold pipe and install it's own water heater.
From what it sounds like I'd say 30-60k depends on quite a bit of factors.
Get someone out that can design a good layout but you need building plans to start any construction of plumbing,electrical,framing and foundation work. Engineering is where you start and talking to your local building department.

 

[RamJacCorp]

Thanks for the response, Rossando! I'm hoping your estimate is for the entire project, and not just the plumbing, or we're dead in the water. (pun intended)