I have a 2000 Summerset 16x76 that have a 3000w Inverter, 20kw Kohler and 16 batteries in the front bay

About every three months I am having to refill those front batteries with about 6-7 gallons of distilled water.

This is a pain and also seems like a lot.

I had heard that this much lost might be caused by batteries that are overcharging?

Any thoughts on the quantity? If this is a problem any way to fix it?

Thanks for the help

Do a voltage check on your batteries (use a digital multimeter set on DC volts, 20 volt scale). A fully charged 12 volt system should read between 13.2 and 13.8 volts - it shouldn't ever get to 14 volts. If it does go over 13.8 volts, your charger likely needs work, as it is overcharging the batteries. Also, have a load test done on the batteries themselves. If one has a bad cell and calls for a charge all the time, it can lead to the rest of the batteries becoming overcharged - depending on the type of charger you have. I'd check them more often than every three months though, especialy during the summer months. Boat batteries' average life is between three and four years, so you're getting close to the end of their useful life if they are original to the boat...
Vic Willman38050.2913657407