Fresh Water Tank Capacity

[AmeliaKD]

Are you folks metering how much water goes into?
Like with a device like this?
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I plan on ordering one! I measured this time using 5 gallon water containers as we weren't near a connectable water source. I should have been able to load over 10 of them (52 gallons), but got to 8 (about 40 gallons) and it started to overflow. Before we starting siphoning in the water, we were getting air out of the faucets so I assume it was completely empty.

[firstshirt]

Sorry - I forgot to update this thread when I found the problem. Turns out that my P3 Save-a-Drop water flow meter is not properly calibrated. I did a test and discovered that it was reading low; I filled a 5 gallon jug and it read 3 gallons. So it makes sense that when it says 40 gallons there are actually 60 gallons in the tank.

[huntindog]

Interesting! Can you elaborate on "I raised the vent plumbing to the hieght of the top of the propane tanks,"?

I did similar to post #26 in this thread:
https://www.mygrandrv.com/forum/show...ght=water+loss
I have two FW tanks that are plumbed togther via a pipe, so the pump draws them down as one large tank. Both tanks have their own fills and vents though. So I tied the vents together using tees, and each tank has a ball valve on its vent that can be opened when filling, just as GD intended. Once they each start to vent water, I close them, and continue adding water until it comes out the raised vent in the propane compartment. No need to remember to open the valves as the raised vent allows air to enter as water is used.
In theory, I should be able to fill without opening the valves, but sincn I have a large tank connected to a small tank, I need to know when they are both full. for those with a single tank leaving it closed should work fine.

Opening the valves is probably a good idea when dumping the FW, as that is a lot of flow, and the raised vent may not keep up.

[aljewett]

Weird. I just got the same meter and filled my 204 liter tank with 150 liters, just to the overflow. (Canada, eh!) Also, filling the black tank via the toilet comes up short too, by about 12 USG. I checked the calibration of the meter, and it's pretty good; meter reads 14 liters after filling a 15 liter jug, so I don't think it's the meter. So, what's with Grand Design inflating the tank numbers?