There's a little bit of confusion among consumers out there concerning the "ethanol in gas" issue. Specifically, what additives can or will do about the ethanol in the fuel. Many people ask if an additive will "remove ethanol" from gasoline. It's important to have an accurate grasp on the issue so you can make an informed decision if you ever find yourself considering ethanol fuel treatment.
Removing Ethanol From Gas?
Ethanol is mixed into a ready gasoline "feedstock" at the fuel terminal. Typically, it's done by splash blending in fuel trucks. The ethanol itself is trucked in by big rig or rail car (since it can't go through the same pipelines as other parts of the fuel). Once it is blended into gasoline, there's no feasible way to separate ethanol from the gasoline. Once it's in, it's in to stay.
Unless.....it absorbs so much water that it undergoes phase separation. In that case, both the ethanol and the water will separate out together. Now you've got all or some of the ethanol out of the gasoline. Unfortunately, the gasoline left behind has lost a lot of its octane value because the ethanol will strip out valuable fuel components as it is leaving.
So adding water to gasoline just to remove the ethanol you don't want is not a good idea. It would do far more harm than good.
Can Fuel Additives Remove Ethanol?
The short answer is no. Any fuel additive that claims to actually remove ethanol from blended gasoline is something you'd want to stay away from, because who knows what other overtly false claims they're making. There's no fuel additive that could do that, nor should any imply that they do.
What a (good) fuel additive should do is provide active ingredients that fight against the negative effects that ethanol causes in the fuel or in the engine.
Since ethanol's downsides have to do with poor mileage, corrosion, solvency and water absorption, a reputable ethanol fuel treatment will talk about the things it can do to help blunt or solve those problems. It would never claim to or imply that it could actually remove ethanol from gasoline it's already blended into.