Toto Drake CST744 E or S -- tight fit to wall and counter top?

Hi all
Bath #1: Toilet must fit under a low countertop which is 29 3/4 from floor to underside. Counter sticks out 7 3/4 from wall. 11 1/2 rough-in to finished drywall. Toto Drake CST744E (1.28gpf) and CST744S (1.6gpf) have a spec height of 28 1/2. Sounds tight -- will this be enough room with tank lid off to service tank parts in the future?

Bath #2: This bath has no countertop to deal with. I'd like to put same toilet in, but it's only 10 7/8 rough-in to the finish side of a ceramic tile wall. Toto spec https://terrylove.com/pdf/cst744sg-specs.pdf
shows if 12 to wall you have 1 1/8 rear clearance. So with my 10 7/8 to wall, it would be zero clearance. Will this work, or is there a better choice? I have room to go any height.

Also, is 1.6gpf legal in California still? I assume 1.6 is better (helps avoid dry drain, etc.)

thanks for any advice, Jim

Someone said (at least in some parts of CA) 1.28g is required now, and I think it was San Diego that was included. A call to your local building department should tell you if you can't find it online.

Zero clearance is only an issue with potential condensation with the tank tight against the wall - functionally, it would work, and, while the low-flush toilets often don't have a problem with condensation, it can still happen if the RH is high, the incoming water is cold, and the toilet is flushed before the tank water can warm up to room temp (course, if it's foggy, that may not be enough to stop condensation). Pretty much all newer toilets do not use all of the water in the tank, so mixing the refill water with the (hopefully) warmer tank water keeps it above the dew point unless it gets flushed repeatedly without time in between.

It might be tough doing something like change the flapper without pulling the whole toilet. Someone will be able to measure the thickness of the tank to give you an idea of what, if any, space is available, but I don't think it will be much, to get your arm in there.

You usually will have a little "fudge" room on the rough in by sliding the toilet forward on the flange. A one piece toilet is considerably lower than a two piece, so that might be a worthwhile consideration for you. Another consideration for the 10-7/8" rough in is one of the Toto toilets using a 10" Unifit adapter. These toilets would fit nicely in the space and are very attractive units as well. One piece are easier to keep clean which is another advantage. Just keep in mind the Unifit adapters only work on specific models of Toto toilets and not at all on any other brand.

I have an original Drake at 11". It's just about against the wall. It's going to depend upon how accurate that measurement is, and, as Terry once said, how true that wall is (i.e. is it really vertical), because if you're right at the margin and then the wall bends inwards, then you're screwed. But there's usually a little more than 11 so you could usually get it on 10-7/8. That's probably the only one in the Toto line that can fit on the 10-7/8. Gary is correct that one of the units with the Unifit can take it to 10".

Similarly, because the Drake's lid doesn't need to be lifted much to get it off, that clearance above it isn't going to be a problem just to get the lid off. Getting in there to change parts may be a little harder, however, but if you use a dental mirror or something, you'll probably be able to see what you need to in order to, say, change a flapper. Remember that you probably get around another 1.5" when you remove the lid, so you should take that into account.

People say that the Eco-Drake CST744E works very well on 1.28gpf. I have the CST744S (1.6), but I wouldn't be concerned about the 1.28.