This may be of some help, since our 2000 model is likely very similar. That said, I wouldn't put it past the manufacturers of these things to change the items depending on availability, cost, need for improvements, etc.
The gray water and fresh water tanks are listed as 17 gallons each. The water heater holds another 6 gallons of fresh water, of course.
Since the freshwater tank is mounted transversely there is some variation in how much you can get out of it without refilling, since the pickup point could be higher if the street side is higher (trailer not level). If I were to design a freshwater tank I would shape it so the full capacity is available independent of leveling. That might even involve two vents, one on each end of the tank in order to allow complete filling regardless of level or not.
My practice is to top up the tank more often than absolutely necessary, partially because it is a nuisance to have to purge the system after the pump has been trying to suck up air. Think jackhammer.
If I had to replace the tanks I would opt for 20-22 gallon capacity units, but the downside is that there is a temptation to add more weight
to the trailer. Fortunately these tanks are close to the axle
, so the towing characteristics are quite constant regardless of how full they are.
I'd be happy to share some of my findings about these units, since ours is "enhanced," and the expected trouble areas have pretty much been dealt with. Great trailer, with exceptional possibilities for customization. Email me for more information.