IF WATER IS HAVING HYDROGEN AND OXYGEN WITHIN IT AS BOTH HELPS IN ENTTHEN WHY WATER IS A NON COMBUSTIN A

First, the proportion of water molecules are much, much greater than the oxygen present.

Second, the oxygen present in water are solvated. They are trapped, in their ion form, within 'cages' of water molecules. Thus water does not support combustion.

AH..I thought you were referring to dissolved Oxygen instead of Oxygen atoms present in water molecules. -_- In water molecules, as mentioned above, the oxygen atoms is strongly bonded by covalent bonds to the Hydrogen atoms. As such, even when heated, water will only undergo a change of phase. Properties of a compound is different from its constituting elements.