After filling up my gas tank, I forgot to close both the gas cap and lid. That's not the worse part, I went thru a drive-thru car wash.

I discovered the mishap when I got home, but I don't know how much water has gotten inside the tank, if any. The car is still running fine with no issues. Should I be worry and what should I do? I have `15 gals. of gasoline in the tank, so draining the tank is gonna be a PITA. Are there additives I can use to remove the water?

I always thought all Hondas have a secondary gas lid at the fuel filler neck. My 99 Accord V6 doesn't, and that thing could have saved me today.

 

i don't know if the saying "watered down gas" is real and should be taken literally or its just a saying ... but id be more worried about soap getting in there than water ... if you don't want to drain your tank i suggest filling up your tank and thinning up whatever is left in there ...

 

If you are worried about water and soap mixed fuel, I woudl be, there is a drain plug in the botom of the tank. You can drain your gas tank and check its contents. If it foams up or has water droplets in it. Then dont re-use it. If it comes out soap and water free you can re-use it. It's a pretty simple process.

Cheers

 

They usually provide a deeper than required sump in these gas tanks for things just as this. The fuel pickup / Pump assembly sits off the bottom, so initially you should be ok. But I wouldn't wait too long.
Throw a couple of cans of Dry Gas (Gunk, Etc) in the filler tube and the contents will start binding with any water that may have made it into the fuel tank. This will allow the engine to burn it off during normal driving.
I'd be more concerned about rust forming on the inside surface. If left in there to it's own devises, the water might make a new drain plug for you.....

P