Unless your water is from Perrier, and the same for sewer (?). The rates you are noting are exorbitant.
Therefore first things first, be sure the rates are monthly and not bi-monthly. Secondly, find your state's utility regulatory authority, if your supplier is not under their jurisdiction, contact the city and county government. Some judicial or quasi-judicial board had to publicly approved the rates. Most city and county records are on-line, then googling "Water Rates". The reason I stress this is we have found numerous municipal water suppliers misinterpreting the "approved" rates. For example: Are you credited base fees for periodically vacant units ?
After auditing the water rates, look for water leaks most MHP's' use @ 1000 gallons per a single occupant, or 2,000 gallons if they have a laundry (For example 2 occupants w/laundry = 4,000 gallons per month) While every MHP is different, based on our 20 + years of sub-metering service through out the US, $45 to $75 is an approximate range for a typical MHP. Also, keep in mind when tenants pay for their own water use, usage drops 25 to 35%. Ad maybe your MHP residents will get involved, politically, to who is responsible for your exorbitant water/sewer rates
If you need some additional help, We’re here to answer your sub-metering questions.
Southern Water Management
727-827-4509 cell 727-421-9695