I’m not yet ready to tackle LA River water, but having a way to filter large amounts of water efficiently will be useful for me, given that I am not the kind of guy who could easily say no to anyone in need and too many friends already know I am somewhat prepared in case of emergency.  My current water storage is two 275 gallon IBC totes filled with city water and sitting behind my house in the dog kennel, covered with a tarp.  I need to build a bit of a more permanent shed, with some dry storage shelves above.

As for filtration, I am dropping a few links that will help me design a system.  A few of these are all variations on the same theme, a candle or dome ceramic filter between 2 buckets or barrels.  I want to add a prefilter for larger solids that is made of cheesecloth/pond biofilter materials then segmented gravel/sand/activated charcoal stages separated by screens, and maybe even a UV stage (in case there is power available, even solar since it only runs a few mins) before the ceramic filters.  

plans/parts/sources/ideas:

http://www.stpaulmercantile.com/BucketFilter.pdf

http://www.purewaterproducts.com/

http://www.cheaperthandirt.com/CAMP354-1.html

http://www.alpharubicon.com/kids/homemadeberkeydaire.htm

http://www.biosandfilter.org/biosandfilter/files/webfiles/BioSandFilter_Construction_Guidelines.pdf

http://www.buyactivatedcharcoal.com/charcoal_water_filter

http://www.breadandbutterscience.com/I38.htm

and in case I need to distill water:  http://www.coppermoonshinestills.com/index.html