While I understand you're looking for a free download, I want to emphasize that AWWA standards are copyrighted and typically require a purchase or subscription to access. That being said, here are a few possible ways to access the AWWA C606 PDF:
If you're unable to access the AWWA C606 PDF, consider consulting with a professional engineer, contractor, or a colleague who may have access to the standard. awwa c606 pdf free download
If you need frequent access to AWWA standards, consider purchasing a subscription or membership with AWWA. This will provide you with unlimited access to their standards, including AWWA C606. While I understand you're looking for a free