The bumber of bathrooms depends on the usage of the building.
For instance if it a dry storage warehouse with 2 employees, you will only need one or two single toilet
restrooms in most areas.
The building codes including any local changes to it have all that spelled out in detail in their building code manuals.
If it is a night club, group of restaurants or theater that holds hundreds of people you will need more accommodations... or just two bathrooms but with 5 urinals. 5 sinks and 5 toilets for the men. and a similar arrangement for the women.
Those can be communal bathrooms in some cases shared by all of the businesses within the 10,000 square feet, as you see in many shopping malls, that varies with the nature of each business inside.
To stay entirely out of trouble, regardless of what I might say, or the local building code might say, you should hire an architect to discuss all this with you... it can get very complex.
Restaurants require their own separate facilities in many cases, there is the issue of handicapped access which can get complex... extra wide door ways and height limits of the sinks, and fixtures etc.
And there is the issue of perhaps roughing in plumbing under the slab to accommodate changes in those facilities as one tenant moves out and another tenant moves in. You would do this for your own future protection and to make the building more salable when the time comes.
Most architects will charge you upwards of $1,000 to research that for you, and even then only as part of a larger contract do design the interior.
That is the best answer I can give at this time with the information I have.
If you would like me to review the local codes I will do that if you rate my input so far positively. If you do, I can spend the 2 or 3 additional hours required... getting into the building design and usage nuances
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