The windscreen washer bottle is inside the engine compartment on the Right Hand Side (driver side) of the car - or on the left as you stand looking into the engine bay!- it's behind the headlight.
Adding water to the coolant reservoir won't do any harm. The coolant is a mixture of anti-freeze (ethylene glycol) and water anyway. The worst it will do is dilute the mixture and given that the coolant reservoir isn't that big - much smaller than the windscreen wash bottle and was probably nearly full anyway, you can't have added much water!
JD, January 2008
