depends on the system i have with them..... and the water i have to deal with .... i have seen bad water and ok water and frankly sparkling water but still treat...

in my mini kit , i have coffee filter prefilters, and tablets , and most water is boiled before used....

in my hiking pack
i have a gravity bladder system that can gets me a couple liters fairly easy and its tiny.. with 1 dirty bag and a bag to put it in , and one on my back to filter into... as well as tabs...

in my truck
right now i have a few gallons of water , and im working on getting a bigger set up with a pressure syphon

in the cabin... right now theres a still and a large in palce filter sets ready to be put in once i have the land ... with a 100 gallon holding tank.... and clorine.... and a supply of sealed carbon filters and membraine

the more i researched water treatment it has many variables.... as i can carry more weight i carry better gear taht can take contaminates down quickly.... and produce a larger volume of safe-ish water... its very hard to be 100% sure mind you. but i did have a couple really bad run ins with backpackers plauges while in the boy scouts and i hope never to repeat it.