We've been drinking the water out of our tank since it was new. Never got sick. With that being said I sanitize it every year. Also when filling I fill till it overflows. If I go by the fresh water gage it would never get filled. Both the gage and the pump draw tube are off. I can keep filling for quite a while after it shows full. And just the opposite when using it. It will show 1/3 but then it starts sucking air. I then add two 7 gal jugs of water to get by for one more day. Then when I get home and pull the drain it empties a lot of water. Probably 10 gals. So the point is your gages are probably not correct so filling to the overflow will guarantee you have a full tank.