Haw. Code R. § 16-605-63
A water carrier that is also engaged in nonregulated business shall allocate its common expenses between its regulated and nonregulated business. It shall make the allocation following the commission's standards, or if no commission standards are available, on the basis of time studies, usage, per cent of revenues, or any other generally accepted method of allocation. In addition, any expenses that may be allocated to the water carrier by affiliated companies or by the carrier to affiliates, regardless of whether those affiliates are regulated or unregulated, shall be supported by records that clearly demonstrate an allocation method in compliance with the commission's standards, or if no commission standards are available, on the basis of any other generally accepted method of allocation.
Haw. Code R. § 16-605-63