Sounds like the complex

[just someone]

Sounds like the complex needs individual water meters, or at least the ability to turn off individual units.

Also, if complex has a pool/spa, etc, she should demand that common area privileges be taken away from units with non-payment.

If owner of the non-paying unit is not in bankruptcy, HOA’s need to be smart, and go after owners in small claims court, rather than a lien.