Not quite as simple as too much water. That is the primary cause but not only factor. Available nutrients is another. No way to know if you are over-watering or not with details on what your watering regimen is.

General guidelines are 1-2 inches of water per week, deep watering less frequently rather than frequent shallow watering, and most important keeping consistent soil moisture levels.

You can pick at color break and finish ripening indoors to eliminate last minute water overloads in the fruit.

Dave

I've always had watery/bland tomatoes as the first ones
every year. They'll get better.