Cisterns are regulated by the Spokane Regional Health District (SRHD).  We recommend you visit their website for Guidelines for Cistern Water Systems.

On this page, there is a link to the cistern guidelines:
Drinking Water (Private Wells)

Additionally, you may find useful information on this page which also includes related water links at the bottom:
On-Site Sewage Systems

For additional information, we recommend you contact the SRHD at (509) 324-1500 or email them via their SRHD Contacts page.