Water is made from two elements - Hydrogen and Oxygen. If you put the two gases together, along with energy, you can make water.
\[
2 \mathrm{H}_{2}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g}) \rightleftharpoons 2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l})
\]