Has the violet ray been used to alter water?

Do you mean ultraviolet (UV) light? It's necessary to make this clear,
because violet is a bandwidth of light different from ultraviolet.
Violet is easily visible to the unaided eye, whereas UV is invisible
to the eye.

ya qed is right.
UV rays are most widely used to purify water.So they can pass through
water and will harmful bacteria and viruses in water.So if u meant uv
rays then the answer wud be yes.

The Ultra Violet (U.V.) is a radiation enegetic enough to cause the
promotion of the upper molecular electons to higher energy states,
therefor this can breake intermolecular bonds in organic molecules.
But before one bond is broken, the photon energy must be absorbed. The
maximum absortion wavelenght for the water is 167nm.
Conclusion: Far U.V. (wavelenghts lower than 200) can cause alteration
on water, such as formation of radical forms of oxigen or ozone
dilutions in water. In the other hand, I think that a lamp emiting far
U.V. it's not very common.

Devices based on UV lamps have long been used to sterilize water, for
home and commercial applications (such as bottled water, food and
beverage manufacture) They usually use quartz light tubes which block
less UV than glass, and pass the water in a thin layer over/between
the tubes.  UV will act directly on organic compounds and
micro-organisms, breaking bonds and sterilizing the organisms. I don't
think the UV generates oxygen radicals, or causes any change in the
water.Search with Google, include 'UV' term and whatever application
you are interested in (water sterilization, for instance.)