That works. X2 what 8iron said. Make sure to drain fresh water holding tank completely using the low drain point (cap under trailer, thru skirting)....then check guage to make sure its empty (no more water flowing out of low drain point would be evidence enough). Then try filling up with your 5 gallon jugs to see if you canget at least 6full jugs in.You can most likely still get more water in tank even after guage shows full. Don't go by guage showing its full...thats only a general reference, not 100% accurate. Keep us posted when you solve this mystery!
Nancy + Tony
'11 Dodge Laramie Longhorn CC
'12 Sunset Trail ST25RB
When we fill our fresh water tank up with a hose, sometimes the water will start backing up, making you feel like it must be full, we check the monitor and it only reads 2/3 full. Make sure you don't have your water pump on (I think this may cause the system to pressurize and not allow you to fill it full), we just turn the water off, let whatever water is backing up drain out and try again, sometimes doing this a couple of times and then it will read full.
Just thought i'd throw out there, if you ever have a tank and need an approximate gallon range the calculation is L x W x H divide by 231 will give you the approx. gallons (give or take due to differing wall thickness). If you ever have the need for a new tank please check out Rv Tanks at Plastic-Mart.com. We appreciate you.
We're always available to assist anyway we can.