This issue has come up across the country, as municipalities struggle under fiscal constraints, they are reluctant to provide or be responsible "ie accuracy" for individual meters in MHP communities.
Regarding the County installing one main meter, the municipal supplier most likely does not want the maintenance of the individual meters (which may actually belong to the MHP); Has investigated the water usage and determined the older individual meters are not accurate, noting older meters do not capture 100% of the usage; Reading one new meter is far easier than traversing through your MHP reading individual meters.
You can still bill the residents based on their sub-meters: If you use a third party billing service, pass through the reading/billing/collecting fees, which may actually be less than what the residents previously paid the City, (only one base fee for the one new main meter is shared now by all of your residents). In addition, the difference from the main and the individuals meters can allocated back to the residents.
Let me know if I can be of additional help.
We’re here to answer your water sub-metering questions.
Southern Water Management