I am turning my garage into two bedrooms and a bath. Problem is the floor is concrete and the closest water source already plumbed in is about 40 feet away. However, the water line to the main house goes along the outside of the garage wall. Can I tap into it at that source instead of going to the current connection? I would install a "hot water on demand" for the hot water needs in the new bathroom only?? I will have to cut a section of the floor out to install the sewer/wastewater lines also. I could put both incoming and outgoing water in at the same time and use the same ditch at different levels?

I am turning my garage into two bedrooms and a bath. Problem is the floor is concrete and the closest water source already plumbed in is about 40 feet away. However, the water line to the main house goes along the outside of the garage wall. Can I tap into it at that source instead of going to the current connection?
answer... yes

I would install a "hot water on demand" for the hot water needs in the new bathroom only????
answer... i would probably put a 30 gallon lowboy heater in a closet

I will have to cut a section of the floor out to install the sewer/wastewater lines also. I could put both incoming and outgoing water in at the same time and use the same ditch at different levels?
Answer... the rule on potable water and drain piping in the same ditch is 1 foot over and 1 foot up.

answer... the rule on potable water and drain piping in the same ditch is 1 foot over and 1 foot up.

Be aware that the sewer line must drop 1/4" per lineal foot of run.