An expenditure of public funds under section 5117 for the care of an individual is considered an expenditure for the protection of the public health, and not money advanced as welfare or relief. An individual is not legally obligated to reimburse the expense incurred, unless the department and the county of domicile, after reasonable notice and upon a hearing, find that the individual hospitalized or treated, or the persons legally liable for the individual's support, are possessed of sufficient income or estate to enable them to make the reimbursement in whole or in part without materially affecting their reasonable economic security or support, in view of their respective resources, obligations, and responsibilities to dependents and order reimbursement. The order shall not be made retroactive unless the department and the county of domicile find that the person to be charged is guilty of misrepresenting or withholding knowledge of facts material to the issue. Receipts under the order, and money voluntarily paid as reimbursement, shall be distributed pro rata to the funds out of which the expenditure was made.