New basement bathtub question

I am installing a bathtub in my basement that has rough-in plumbing. The rough-in bathtub floor drain stub out is about 1" under water in the drain box. What are my option for connecting the drain trap to a stub out that's a little under water?

Use a shop-vac to see if you can suck the hole down enough to work. There may be no trap in the rough-in, and the pipe may need to be cut to fit. If your rough in is cast iron (as it should be in Chicago), use a shielded coupler to attach a trap. If you are working with PVC, hopefully you can suck the water level down long enough to prime and cement, but you could use a shielded coupler there too if need be.

If you cannot get the water level down, you might need to dig another hole nearby to drop a trash pump into so you can try to temporarily pump down the water level around your work area.

It is PVC as I am actually a little outside of Chicago. Should I use a p or s trap for a bathtub? Worst case is it a good idea to use a compression PVC fitting to attach to existing PVC drain?

A p-trap is the only approved fitting.

Not sure what you are referring to by compression fitting. A banded coupler or pvc cement are 2 proper ways to make the connection.

If there is a riser coming up vertically, there may already be a trap there.

http://www.fernco.com/img/products/plumbing/shielded-couplings/shielded-couplings-proflex.jpg

An S-trap is never a good idea, and won't meet code (and, it must be vented). A compression fitting requires you to have access after setting the tub, but if you do, also means you can more easily remove the thing, should you ever desire it. If you glue the whole thing together, you only get one chance unless you have that access. If you don't want to use compression fittings, you can make the connection with a nohub fitting, assuming you have access, to connect the drain to the existing plumbing.

I'd be more worried that you have standing water there. Is this ground water?

The water in the pit is ground water. I like the idea of using the flexible rubber coupling with some stainless hose clamps. Once the p trap is installed is it okay for me just to back fill the drain box in the floor with gravel?

I want to make sure you get the right coupling so I will point out that this is not "flexible" per say. The coupling I recommend has a stainless steel band all the way around it which makes it rigid. This will prevent the pipes from shifting or becoming misaligned.

You can backfill and pour concrete over the box. That's why you want to make sure your installation is proper and long lasting.

It sounds like you are in the South suburbs. As soon as you "open" the drain line ALL the water in the area is going to start draining into it, so you have to be ready to make a quick connection. The banded coupling is about the only option with the pipe under water.