Splitting water is easiest thing in the earth. All you need is a source of direct current a.k.a battery eliminator, some long wire, a plastic dish (deep) to keep water and couple of test tubes to collect what comes out of the split.
Tie the test tubes as shown with a cloth clip using a rubber band. Fill the tubes with water, add some salt to reduce the resistance. Shove open end of the cable inside test tube.
It may be a good idea to attach a gas carbon rod taken out from battery. This will protect the wire from erosion.
Once you do this, as I have done – you will notice bubbles coming out from end of the wire. These are Hydrogen and Oxygen.
What we did – is known as electrolysis a big word that means splitting by electricity.
Try electrolysis with concentrated salt water, let me know what did you notice.