Sorry to hear that you have the sensation that there is water in your ear. This can be a very frustrating problem. There are a number of different things that could be going on. The first and obvious one is that there might actually be water in your ear. This is usually temporary, and judging by the fact that you say you know there's not water in your ear, this has likely been going on for some time (and thus is probably not due to water). Sometimes if there is excess cerumen (wax) in your external auditory canal, it can obstruct the ear canal muffling sound, and giving the sensation that your ear is "plugged" with water. The cerumen can also come into contact with your tympanic membrane (ear drum) which will sometimes cause a crackling or muffled sound which can be interpreted as "water in the ear". Another fairly common problem that can cause abnormal noises in the ear, and occasional pressure and a "muffled" sound is something called eustachian tube dysfunction. The eustachian tube is a small muscular tube that allows air to go from the back of your nose to your middle ear to equalize pressure. If the tube isn't working properly it can lead to a pressure imbalance, and retraction of the ear drum. All of these different possible scenarios can be diagnosed by a general otolaryngologist
(ENT), who I would recommend that you see. Best of luck.