Update: After one of the scientists who is terrorizing the community of Wilmington with manipulative information came here nitpicking the following calculations, we need to state that for the following exercise we took a microgram and converted it to a drop unit, as an analogous representation, in order to help people who are not water experts be able to visualize what the parts per trillion measurement might look like in real world terms.
The US EPA determines the amount of chemicals in water by measuring in parts per million (ppm), or parts per billion (ppb), and parts per trillion (ppt).
GenX, when it was first discovered by EPA scientists trying to determine what chemicals had been created to replace the now discontinued C8 that has been used in the manufacturing process for Teflon, was found to be at a level of 631 parts per trillion.
Parts per trillion equals 1 drop of impurity per 500,000 barrels of water.
500,000 barrels of water equals 21,500,000 gallons, or the size of about 36 Olympic sized swimming pools, which is roughly 65 acre feet of water.
For comparison, the US Capitol Rotunda is about 32.5 acre feet. If one were to flip the rotunda upside down and fill it up with water, that would only be half the amount of fluid used in the parts per trillion measurement.
Since the EPA’s discovery of GenX, Chemour has stated that they have been able to reduce the amount of chemical output to around 100 parts per trillion, or less than a teaspoon per 21,500,000 gallons of water.
Shortly after we published this information, an EPA spokesman from the US EPA’s Press Office wrote back to us with a formal statement about the status of creating a regulation benchmark for GenX in drinking water:
Drop unit: https://en.wikipedia.org/wiki/Drop_(unit)
Parts per billion/trillion: http://www.secnav.navy.mil/eie/Pages/DrinkingWaterConcentrations.aspx
Barrel unit: https://en.wikipedia.org/wiki/Barrel_(unit)
Discovery of GenX: https://theintercept.com/2016/03/03/how-dupont-concealed-the-dangers-of-the-new-teflon-toxin/
Capitol Building Acre Feet: http://www.bluebulbprojects.com/measureofthings/results.php?comp=volume&unit=af&amt=65&sort=pr&p=1