Originally Posted by Mellinkat
We are considering buying a 2008 Safari 25 that has an 18 gallon black water tank. Is it possible to install a larger capacity tank?
Usually not, without extensive modifications to the frame.
Your present tanks have filled the room available withinn certain frame cross members.
You could increase the size of it vertially, but then you would have to design and installa steel frame to support it, that would lower the underbelly. That would also make you empty that tank before any travel, because if it was near full, you would have altered the toungue weight, which would alter the trailer handling when it's towed, plus adding additional weight to the rear, which the original design will not handle when hitting bumps.