We've had two adults and two dogs using a travel Berkey. We run at least 4 gallons through it daily and we went more than two years before we had to change the filters, and we didn't "have" to even then really, it still worked. You just use the priming ring to run tap water through it in the reverse direction and it will clear out all of the turbidity and other crap - that and lightly scour the outside of the filters with a brush every six months or so. It's absolutely the cheapest way to filter water when you take into account how long the filters last. It also cleans a gallon of water very quickly. We use it for all our drinking and cooking water and never really run out unless we are making a large pot of pasta. For drinking water, if you like carbonated water, get a sodastream with an adapter so you can refill the CO2 cartridges at brewery stores for pennies.