Question

hcl is a acid but water is not

Answer 1

water can act as an acid or a base

Answer 2

but why is it so it has got h in its formulae so it should work as an acid not base

Answer 3

Think of H2O has H-OH

See, it has hydrogen, a characteristic of acids
But it also has -OH, a characteristic of bases!
So it is both an Acid AND a base!

HCl , H-Cl, just has hydrogen, so it is only a strong acid. :)

Answer 4

There are 3 definitions for acids and bases. read them over here: http://www.chemguide.co.uk/physical/acidbaseeqia/theories.html

Water fits into both, lewis and bronsted-lowry acid-base definitions. Since it can act as both an acid and a base, it is called amphoteric.

Depending on what it's reacting with, it can either accept or donate a proton.

Acting as an acid: \(H_2O+HCl\rightarrow H_3O^++Cl^-\)

Acting as a base: \(H_2O+NH_3\rightarrow OH^-+NH_4^+\)