After years of study and discussion, the Hawaii County Council is poised to notably loosen its limits on accessory dwelling units (ADUs). Bill 123 streamlines requirements, setting two main rules: service by a state Department of Health-approved sewage disposal system; and access to potable water, whether by a water company, catchment system or well.

Bill 123’s big advance is in allowing up to three ADUs on a single lot — more lenient than the state law enacted this year requiring that counties prepare to allow at least two ADUs on suitable residential properties.