If you are saying that the odor is especially pungent, I would take her to the doctor as this could suggest a UTI or bladder infection. If left untreated, these can cause kidney infections and they are especially painful. I don't know if a 5 month old can get these, but I know that water will not help...
That said, I asked my son's dr. about giving him water as an infant (he was constipated) and his response (however obnoxious sounding to me at the time) was "our bodies are made of 98% percent water, so why would you think that would hurt him?" And when you make the powdered formula, you use water...
But it sounds like that is not the problem. One other thing to look for if the urine has a more pungent smell is the color: is it darker than normal? This could also suggest an infection.
Good luck!