Science, Tech, Math › Science Can You Really Run Your Car on Water? Share Flipboard Email Print Onfokus/Getty Images Science Chemistry Projects & Experiments Basics Chemical Laws Molecules Periodic Table Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated February 07, 2019 Since posting instructions for making biodiesel, many readers have noted that many cars (including mine) run on gas, not diesel, and asking about options for gas-powered vehicles. In particular, I've gotten a lot of questions about whether it is true that you can run your car on water. My answer is yes... and no. How to Run Your Car on Water If your car burns gasoline, it won't burn water per se. However, water (H2O) can be electrolyzed to form HHO or Brown's gas. The HHO is added to the engine's intake, where it mixes with the fuel (gas or diesel), ideally leading it to burn more efficiently, which should cause it to produce fewer emissions. Your vehicle is still using its normal fuel so you will still be buying gas or diesel. The reaction simply allows the fuel to be enriched with hydrogen. The hydrogen isn't in a situation where it could be explosive, so safety isn't a problem. Your engine shouldn't be harmed by the addition of HHO, but... It's Not So Simple Don't be discouraged from trying the conversion, but take the advertising with at least a couple of grains of salt. When reading the ads for converter kits or instructions for doing the conversion yourself, there isn't a lot of talk about the trade-offs involved in doing the conversion. How much are you going to spend making the conversion? You can make a converter for about $100 if you are mechanically inclined, or you could spend a couple thousand dollars if you purchase a converter and have it installed for you. How much is the fuel efficiency actually increased? A lot of different numbers are tossed around; it probably depends on your specific vehicle. A gallon of gas might go further when you supplement it with Brown's gas, but water doesn't spontaneously split itself into its component elements. The electrolysis reaction requires energy from your car's electrical system, so you are using the battery or making your engine work a bit harder to perform the conversion. The hydrogen that is produced by the reaction is used to enhance your fuel efficiency, but oxygen also is produced. The oxygen sensor in a modern car could interpret the readings such that it would cause more fuel to be delivered to the fuel-air mixture, thereby decreasing efficiency and increasing emissions. While HHO can burn more cleanly than gasoline, that does not necessarily mean a car using enriched fuel would produce fewer emissions. If the water converter is highly effective, it seems that enterprising mechanics would be offering to convert cars for people, who would be lining up to increase their fuel efficiency. That isn't happening. The Bottom Line Can you make fuel from water that you can use in your car? Yes. Will the conversion increase your fuel efficiency and save you money? Maybe. If you know what you are doing, probably yes.