Pumping from all 3 water tanks

[DAVID BLOCH]

We rarely pump from our three water tanks, since in the marina we're always connected to city water. But yesterday I wanted to empty all the tanks (doing some level guage testing). The pump ran until it started pumping air and I shut it off. But it turns out it only emptied the aft tank; the other two are still full.
So my question: instead of keeping the three valves on the manifold open all the time, does Hunter really want me to open only one at a time? Is the pump just drawing from that one perhaps because it's the easiest to pull from, and then just sucking air when it's empty?

 

[Stu Jackson]

David, in almost all boats with more than one water tank, one is usually higher than the other(s). When one gets empty, it can suck air. I've made the habit of only using one at a time. When one gets empty, and I know it because it sucks air (!), I switch to the "backup" tank and know to fill the now empty one. It's a great "telltale." It's not so much whether Hunter wants to you go to all that effort of turning a few valves, it's simply how it works and how you can best manage your tanks, with or without tank gauges. I've never felt the need for gauges.

 

[DAVID BLOCH]

YES! You're reply made me did a little deeper. That aft tank is indeed way higher up than the others. Although I had put several gallons of water in it, it looks like the drain for that tank may be a bit off the bottom and it still wasn't sucking it up. I filled that tank completely and the pump is again pulling water.
SO I've put a label on the manifold to remind me of this issue next time. Now my level guages are working properly as well (they weren't and I replaced the panel) which will also be a big help.
THANK YOU STU for your help with this.