Go to
http://www.cawst.org/en/resources/pubsand download
http://www.cawst.org/en/resources/pubs/category/25-fact-sheets-academicand read about this particular water treatment
Household Water Treatment and Safe Storage
Fact Sheet: P&G Purifier of Water
(formerly known as PUR)
Highlights
ferric sulfate is multi-purpose
Can remove significant quantities of heavy metals including arsenic (Shaw Environmental
Inc., 2006, Souter et al., 2003), lead and chromium (Allgood, 2004)
Packet needs to be used within 3 years of manufacture
I don't see any mention of petroleum/oil, but it isn't inconceivable for all that flocculation in presence of sodium carbonate to remove some oil contamination