Replacing Galvanize Steel Pipes with PEX in Multi-Tenant Property

[Tri Phan]

Hello everyone, i have an interest in a multi-tenant property that was built in the early 1900. It has a recent history of water leaks contributed to the existing galvanized steel pipes. These leaks were repaired by the current owner. However, to be on the safe side, i think it's best to replace them all if i were to purchase. The property has 4 levels including a basement level. There are 4 units with 4 bathrooms within the property.  3 out of 4 units have tenants in them. Can anyone provide feedback on costs, time, and impact to the current tenant to have the pipes upgraded to plastic pipes?  Thanks.

Tri