Clay;4307484; said:
Just plan it out. Changing concrete isn't a whole lot of fun, but with proper planning, you can minimize unforseen problems.
I agree with Clay 100%. It's easier to change concrete on paper than it is to do once it's poured. Prior proper planning prevents piss poor problems and performance.
I have a few things I might add though, which came to mind when reading through your thread. With this being a new residential construction and as you mentioned in an earlier post, check with your developer. But most of all check with your architect who will be doing the drawing of the blue prints. He's the one which has the responsibility of getting your plans approved with the state, county or city engineer. I may be wrong here, but it could take an engineer's stamp of approval on the blue prints to begin this proposed tank build if it is to be attached to your house. Not just a county or city residential building inspector.
Ask your architect, what state, county and city building codes say about the structural requirements for your proposed tank construction. It may not be regulated so much by state building codes, but I'm quite certain there will either be county or city building codes, if not both. These building codes are established for not only the safety of your community and neighbors, but also the safety, bennefit, welfare, peace of mind and well being of you and your immediate family.
The code will speak of the type of concrete, the foundation footing size required, placement and size of steel reinforcement rods, placement of framing rough outs for plumbing, windows, deck drains, steps, doors, additional rooms, etc. There could be a minagery of things. Or it could be quite simplistic. But check with your architect and most of all, ASK HIM QUESTIONS YOU'RE UNSURE OF. This cannot be emphasized enough.
It might be good to read the building codes, so you, yourself have a better understanding of what is required. You'll have a better understanding when the architect explains things to you (limited confusion). Additionally, it will not be so shocking when it comes time to drawing the blue prints and the actual build, as to what is being done and needs to be done for completion on the job site itself.
Having this knowledge, as Clay states, will minimize unforseen problems, too.
I wish you much luck and happiness with this endeavor.