How to install a softener for a Individual flat within a apartment.other flat owners refuse to own adjectives softnr I'm a service person.i get a client who wants a softner contained...

I'm a service person.i get a client who wants a softner contained by his flat (for 3 bathrooms,1 kitchen are all aat different location inside the flat & have separate pipeline from Overhead tank).how can i install one softner so it will give soft hose to all 3 Bath.1kitch ?.
the entity is source water is from overhead container which is common dampen tank for adjectives the flat owners in the apartment.and nobody requirements a water softner.

where on earth to place water softner so that i can make a contribution softwater to all needed rooms.
how to put softner so that simply one flat owner will have soft river where other flat owners don't enjoy softwater


is the details is enough?..
How long it take to redeploy soil stack??
Answers:    Where's the source for hot sea for the apt? Does the client have their own? Cause right since that would seem to be the best.