Here is an article that talks about how scientists have discovered where the oil from the BP spill went. It is highly misleading, and I will show you why:
the scientists mapped a huge plume in late June when the well was still leaking. The components of oil were detected in a flow that measured more than a mile wide and more than 650 feet from top to bottom.
A volume of water 22 miles long, a mile wide, and 650 feet tall encompasses 398 billion cubic feet. That volume contains about 3 trillion gallons of liquid. The report goes on to say:
Now federal officials say as much as 42 million gallons of oil may be lurking below the surface in amounts that are much smaller than the width of a human hair.
So even if the entire 42 million gallons is located within the 22 mile long area tested, That gives us a concentration of 1 part per 71,000, or 14 mg per liter (to use the SI standard). The EPA allows 10 mg/l of Xylenes to be present in drinking water. In fact, 14 mg per liter is equivalent to 3 shot glasses poured into your average swimming pool.
The article then says:
The study conclusively shows that a plume exists, that it came from the BP well and that it probably never got close to the surface of the Gulf of Mexico, Camilli said. It is probably even larger than 22 miles long, but scientists had to stop measuring because of Hurricane Alex.
Which means that the Gulf of Mexico, at least as far as oil is concerned, is cleaner than the water from your tap.