Hollow fiber backpacking filters don’t need cartridges and they last a very long time (100,000 gallons for Sawyer filters, supposedly). What happens is they clog up and filtering slows down. You then backflush them by squirting water through them in the reverse direction. If the water isn’t that dirty to start with, you should be ok.

sawyer.com/…/one-gallon-gravity-water-filtration-…

Filter by itself (threads onto soda bottles): sawyer.com/…/mini-water-filtration-system-red