It might not be subconscious. It might actually be an aversion to water because tap water is disgusting (chlorine/metal taste), and filtered water contains no minerals and the taste is off.
When you add stuff to it, lemon, etc. you sense nutrients so you accept it.
I've found that going low carb paleo also leads me to the same kind of state - dry mouth, sometimes coated tongue, feeling thirsty but shunning water. When you go very low carb, your body needs more salt. (The reason for this is that glucose molecules hang on to water, which is why when someone goes on a diet and they restrict carbs they tend to quickly lose 8-10lbs of water weight. But in the long run, this causes dehydration, so we need to switch to something else: salts.)
Going VLC and low salt is a very bad idea. Of course, by salt, I don't mean commercialized salt where it only has sodium-chloride, iodine, and possibly something harmful like aluminum. Rather, go for actual sea-salt where you can get some trace minerals. Better yet, get some concentrated trace minerals...
I wind up going for coffee first, and then tea, in the morning, and that helps. The trick is that both coffee and tea have minerals, beyond the obvious caffeine and flavor.
One thing that has helped is adding concentrated trace minerals to water, and while the taste is weird (a little bit salty and bitter), I tend to like it more than just plain water out of the reverse osmosis filter.
Adding lemon/lime/cucumber to water, adds some flavor cues as to nutrients as well as trace amounts of minerals. (Lemons: Calcium, Copper, Iron, Magnesium, Manganese, Phosphorus, Potassium, Selenium, Sodium, Zinc. Limes: Calcium, Copper, Iron, Magnesium, Manganese,Phosphorus, Potassium, Selenium, Zinc. Cucumbers: Calcium, Copper, Iron, Magnesium, Manganese, Phosphorus, Potassium, Selenium, Sodium, Zinc.) So I'm guessing you were drinking filtered water.
There was some speculation that HG's didn't really drink too much water, rather they got hydration from food (fruit, veggies, animals) and only drank water when needed. Then again, if you look at caves, they usually have pools/streams where the water is very high in minerals, and so we tend to store/regulate sodium, but not magnesium because magnesium was plentiful back then (and it isn't now.) So perhaps those theories aren't fully baked yet, but it makes sense to find filtered water unappetizing and dead.
Another thing I do is to use a sodastream to refill Pellegrino bottles, but I add several drops of trace mineral liquid to each bottle, otherwise it tastes off. So I suspect this is the same mechanism. (Let's see, I can buy a 1L of the real stuff at a grocery store for $4, or I can buy a 12 pack of 750ml bottles from Costco around $15, or I can refill them for pennies.)
Hope this helps, even if it's a year after your original question. :)