Figure 7: Water to Rocket Fuel (and back).

If you prepare your water properly it can provide a big enough boom to be rocket fuel

Most rocket fuels are toxic. Most rely on Nitrogen reactions for the main part of their thrust. Water is just as good (and sometimes better) than other fuels. The difficult part to understand is that it’s only liquid oxygen and hydrogen that make the rockets go. So the fuel has to be kept a lot colder than a freezer. An Ecological launch into space would never use any other fuel. Click the image for a larger version.