Tests find trace levels of contaminant remain in West Virginia water . Federal grand jury investigated chemical spill . The July 9 leak prompted a do - not - use order for up to 300,000 people . The chemicals leaked into the Elk River from a storage tank near the treatment facility .
Tests find trace levels of contaminant remain in West Virginia water . Federal grand jury investigates chemical spill . The January 9 leak prompted a do-not-use order for up to 300,000 people . The chemical spilled into the Elk River from leaking storage tank near water treatment facility .