Lesson Learned - Never blend off a little bad fuel into good fuel

If it isn't a large ratio of water to gas, just add 91% rubbing alcohol or acetone to the gas until the water mixes back in. Ethanol will also work, but why waste it there. I'll also add the IPA(not the beer) or acetone to the equipment's tank at the beginning of the season in case water separated out in the carb over the winter.

 

It likely is water or other things coming out of solution, which the IPA and acetone will likely clean up too. Even if you run the tool dry before storing for winter, there will still be some gas left in the carb bowl to leave some gunk behind.

 

One word: Seafoam. Seafoam is a gas additive (any auto parts store and wallyworld has it) and removes water of gas and it stabilizes gas for up to 3 years and can turn 'bad' gas into useable gas-much more effective than stp or any other gas stabilizer-Seafoam will also clean the gunk out of the lines, carburetor, fuel injectors. I would never use isopropyl (rubbing), alcohol, or methanol in gas-such alcohols erode the rubber parts (gas lines, seals) in small engines, such as lawn mowers, chain saws, leaf blowers, etc... even 10% ethanol (most gas we buy at gas stations) have been know to damage the rubber components. I store a motorcycle in Florida (live in Indiana) and it is not started from 2-6 months. Only thing I do to store it is add seafoam to a full tank of gas-has started every time for 5 years now. All carbureted small engines have a small bowl at the bottom of the carburetor-some have a small screw at the bottom which can be used to completely drain the carburetor. You can add Seafoam to gasoline, diesel, kerosene and add it to engine oil, transmission fluid cases to remove any water which may have developed over time due to condensation.

 

Seafoam is 10 to 20 percent rubbing alcohol.
http://www.sueschauls.com/Seafoam_motor_treatment.pdf

In order to remove water, there has to be a hydrophylic chemical in whatever used to dry gas. Alcohols are the most convenent for the job. Acetone will also work, but a spill will strip off paint.

I've made Seafoam for gas stabilizing. It is used one ounce per gallon.
Homebrew Sea Foam (SeaFoam) Motor Treatment Recipe

 

Phase separation of alcohol/gas blends happens when there is more water than what the alcohol can dissolve into the gasoline. When it occurs, the alcohol also comes out with the water. So the layer you are seeing isn't just water. Adding more alcohol lets the water and alcohol to mix back into the gas. At blend E30 and higher, phase separation isn't a concern.

If you want to make pure isopropanol from the rubbing alcohol, add salt. A unique property of isopropanol is that it doesn't mix with aqueous salt solutions. Add enough salt, and it basically draws the water out of the alcohol into a layer.

If it takes a lot of alcohol to get the layer back into the solution, I'd mix it with a can of fresh gas, and maybe put it in a car's tank.