What planet or fifth world country is this structure located?
I know it cannot be located in any civilized part of this planet.
Lets think about this for one minute OK?
A bathroom lavatory need a washer replaced so according to YOUR primitive code the handyman shuts off the entire building water supply including all fire suppression system if it a common main.
How about this thought someone destroys ONE toilet and the water is pouring out so all 12 units are shut off?
I DON’T THINK SO
Lets ASSUME someone had an ounce of brains and said WAIT A MINUTE this isn’t possible and they ask to see the blue prints or ask the installing contractor for a valve chart.
Every fixture should have an isolation valve or the very least one valve to control each bathroom hot, cold and return circulation lines. Some times these valves are hidden in hung ceilings or access panels or for really CHEAP installations a shut off valve only on each riser
I am sure you have integral stops at each appliance. Possibly key type to prevent vandalism
Even the worst of the worst ********** installer wouldn’t be that stupid and I cannot imagine any building inspector taking that much graft to over look this.
I am curious what country, province or state your building is located.
A Fraud must have been at it again it would appear…