Emergency Order Assurance, Safety, and Inspection of water Systems Act or the Emergency OASIS Act This bill directs the Environmental Protection Agency (EPA) to issue regulations that require community water systems to flush their drinking water distribution systems of contaminants under certain circumstances; it also expands the EPA's emergency powers to address metalloid contaminants in community water systems when state and local authorities have not acted to protect the health of persons in those communities. Specifically, the EPA must issue regulations to require each community water system to flush its distribution system if any contaminant has exceeded the applicable maximum contaminant level for longer than six months or if the drinking water has stood motionless in the system for longer than six months. The EPA may take steps under its emergency powers to test community water systems for metalloid contaminants in drinking water and provide alternative water supplies. Further, the EPA may require the owner of the water system to pay an amount that is at least twice the cost of providing such alternative water supplies.