Can't go wrong with having a hand-pump filter in the "bunker" in case one needs to filter their stored water during a long-term emergency....also handy to "filter" the water stored in the hot water tanks, toilet backs, and tubs (if one is fortunate to fill them at the time of a water shutdown emergency).
I've got that filter along with numerous cases of bottled water, two 55gal barrels (rotate the water/bleach combo every six months....used to have three but gave 1 away after Y2K never took place...wish I had it back), and a dozen 5gal containers (same timeline rotation)...the barrels and containers are "blue" containers specifically made for long-term water storage. At least 2 months worth of water for the fam...and am working up to longer time frame than that. By that point (actually even beforehand), civil disorder will have already been set in anyways....so don't also forget the food stuff in the "bunker", too. The barrels also can come with "hand pumps" for dispensing the water at the time of using it as well as for draining the barrels for the water rotation cycle.