Water Pressure/Plumbing Question

[Adam Belasco]

Hi BP,

Thanks in advance for any help!

Background: I recently purchased a 5,400sqft duplex that was running on one hot water heater which was located in the basement. The property has three floors plus a basement so naturally I'm rehabbing this property to be a triplex (each floor its own unit). Each of the three units will have their own hot water heater located in a utility closet in their unit plus a dishwasher, washing macine, and then one bathroom per unit, with the exception of the first floor which will have 2 full baths (total 4 full baths in property). The property will also have a sprinkler system installed throughout.

Question: Currently we have a 3/4" line coming into the house in the basement from the main line which we're then going to expand to 1". Is that enough to support the 4 full bathrooms throughout the house, one hot water heater in each of the 3 units, plus dishwasher and washing machine in each unit? I was told that it'll be fine, but I'm wondering if I need to spend the extra money, permitting, etc to have the line from the main be changed to a 1" and then tie into a 1 1/4" line in the house?