The nursing home must:

(1) Prohibit all cross connections between potable and nonpotable water;

(2) Use backflow prevention devices on plumbing fixtures, equipment, facilities, buildings, premises or areas which are actual or potential cross-connections to prevent the backflow of water or other liquids, gases, mixtures or substances into a water distribution system or other fixtures, equipment, facilities, buildings or areas; and

(3) Follow guidelines, practices, procedures, interpretations and enforcement as outlined in the manual titled "Accepted Procedure and Practice in Cross-Connection Control; Pacific NW Edition; American Waterworks Association," or any successor manual, referenced in chapter 246-290 WAC for public water supply.