I'm brewing a Barolo wine which is now stabilizing in a carboy with a bubble airlock fitted, the water from the airlock is being drawn into the carboy. Is this normal ? If not how can I stop this ? Will this ruin my brew ?
It's not ideal, but it's probably not a huge problem, either. It's highly unlikely to ruin your brew.
It's most likely happening because the wine in the carboy is cooling, thus reducing pressure inside the carboy, literally sucking the liquid from the airlock like a straw. Did you put the liquid into the carboy hot or warm? What's the ambient temperature in the environment now?
You can stop the problem by using foil over the mouth of the carboy until the temperature stabilizes, then switch to an airlock. Or, just repeatedly (every couple of hours) remove the airlock to allow pressure to equalize, then replace it.
Personally the chances of it ruining your batch is pretty low, but one never wants to risk the off chance that it may result in an infection.
It is from a similar previous experience that I (like many) use cheap vodka for my airlocks since it makes sure things stay clean in the airlock and if some of it seeps back into the fermenter it will not impact the flavor of the brew.
Some people use left over sanitizer, but I avoid this since I have never gotten a definite answer from someone on how long one can use a batch of sanitizer.
Also some people reckon that for primary fermentation (of wine) you don't even need to use an airlock. You can cover the mouth of the carboy with a coffee filter and elastic. The thinking is that you want to maximize the exposure to oxygen during primary to help the yeast. Once you transfer to your secondary that is when the exposure to oxygen really becomes important and that is where the airlocks come in.
But I am too paranoid to try this, so I use airlocks throughout and just make sure that the batch is properly aerated when going into the primary.