No,You are not allowed to pour water on CD or DVDs.
Because water always has mineral substances and these substances are not visible by the naked eye.
These substances lay down on the surface of your CD or DVD and will cause degradation of the quality of your CD or DVD.
So you should use distilled water or a kind of alcohol which is named "Ethanol".
This is what is used in most of cleaning spray cans.
You can simply use Ethanol for cleaning anything related to computers,even electronic boards or lenses of your CD or DVD writer.
Be Careful,just you can't use it for cleaning LCD Monitors or you will destroy its screen.
For LCD Monitors you should buy special spray cans which are harmless to them.
You should be able to buy Ethanol from drugstores.
Pay Attention,I recommend you use Ethanol NOT METHANOL.
Methanol is another kind of alcohol which is a poisonous type of alcohol that can be used as a fuel.
I hope this info is useful for you.