A tenant can be added to the owner's account via this form. Basically, the owner has a "master account" and can see if the bill is being paid, etc. The tenant get's a copy of the bill in their name to their address.

https://www.pgh2o.com/sites/default/files/2019-12/Change%20of%20Address%20OwnerTenant%20-%20fillable.pdf

Owners typically pay the water bill because:

1. The water lines aren't split so there are not separate meters per unit
2. It's the only utility for which the City of Pittsburgh can put a lien on your property if unpaid. So the owner gets stuck with any unpaid balance.

If the tenant has his/her own meter, using the above owner/tenant form allows an owner to get visibility into whether or not the water bill is being paid.

If I was an owner, I'd have the tenant pay for their water and include a clause in the lease that if they are delinquent on PWSA for x days or are delinquent x times, their lease will be terminated but they will still have to pay the remainder of the lease term.

Otherwise, people just don't care about their water usage.