Distributed wells would be more vulnerable to a quake and would take considerable annual costs to maintain potable water.  Although there would be damage to transmission and distribution lines, labor and material resources should be focused on pipeline restoration to provide water for firefighting and sanitation.   Working with SUB or building a plant on the Willamette will still require transmission and distribution pipelines.   There are many other options for bringing in drinking water.   If you haven't planned ahead for a few days, check with your neighbor.   Here is a link to a similar situation in Chile.  http://www.geengineeringsystems.com/ewExternalFiles/Chile%20Water.pdf