O/T Need to add water to a sealed battery.

[BRENT in 10-uh-C]

I need to add some water to a fairly new 12v battery that was inadvertently turned onto its side and some liquid leaked out the vent that is moulded into the top. Since the top is sealed, I am trying to determine my course of action and need some 'brain-power' from the likes of folks here as to whether I am thinking this thru correctly.

As mentioned, a 6 month old 12v battery was turned-over briefly (-by accident) which caused some of the acid to leak onto the floor. The battery was uprighted fairly quickly however some acid did leak out. Upon inspecting the battery, Rural King's battery manufacturer has no intentions of any consumer removing the top of this battery. While I have no idea how much acid escaped, I do feel it likely needs to have one (or more) cells have their liquid replenished to avoid burning up a cell due to lack of acid. Unfortunately the case is black plastic and using a light to see thru the case is not an option.

So after pondering on this for a few days, I think my plan is to add water back into the battery by placing the battery down inside a small Rubbermaid trash can and pour water around the battery until the level rises sufficiently where the water can enter the vent and hopefully replenish the lost acid.
Sooo, am I correct that the battery acid will be heavier than the water which should cause the acid to stay submerged inside of the cell and not float out as the water level is increased?

Does anyone see something I am not thinking about? I am thinking the water level should only rise to the top of the case. If water does rise high enough where the two posts are submerged in (-or touching) the water surrounding the battery, is this going to cause any unexpected 'fireworks' or create a short to the battery?? Based on thinking about the battery tester I have where the charged battery causes the little ball to float (-but not a dead battery), am I correct that the acid is only heavier than water when it is sufficiently charged. If so, discharging the battery in an effort to eliminate 'fireworks' may not be an option if submerging the battery would cause the acid to float away. Based on the design of the case, I am unsure if a syringe would work at refilling thru the vent.

Again, I just want to replenish the missing acid with water in one or more cells but not overfill or cause any unnecessary excitement in that process. Thoughts??