How to treat blood-shot eyes if I don't have Visine eye-drops? Water good or bad idea?
Bad idea. Tears are not water, so water will simply wash them away and cause increased irritation. There are various folk remedies you can try such as placing teabags on your eyes, but in general if you don't have eye drops, removing the source of the irritation that caused them is the only option.
I would add to Carey Gregory answer , that water from tap water has bacteria and would make it worse. There is natural eye drops from herbal extract (but I don't know them all as it is very hard product to compose,some herbs alone can work well) . Other synthetic eye drops can increase irritation or give you toxic effects.
There is plenty of causes of red eyes, make sure you check symptoms for all of them, and then search from there,you'll find a good answer on internet if you look yourself.