What containers do you routinely refill and reuse that most people would throw away?

I reuse lots of containers, but not for what they originally contained. For instance, I have a peanut cannister filled with sequins and beads.

Soap dispenser bottles.

PET bottles.
One or two times, no more.

Most glass jars and bottles are cleaned and reused in my house as I make a lot of my own stuff like condiments, salves, potions, and balms.

Oh, and the more robust plastic take-out containers get used again and again for so many things, freezing food, or holding paint or collecting nails and screws or starting seeds etc etc etc

Not a container, but I keep squeeze tops from catsup, dish soap and the like. When a glob forms, I can then switch out to a clean top, and stick the globby one in the dishwasher.

I routinely wash out and reuse gallon milk jugs.I refill them with filtered water. I have a Brita faucet filter and usually have three gallons on hand.

One of my clearest memories of childhood was milk jugs bobbing on the pond. My grandma used them as bouys for fish lines. My grandpa had the pond put in. It was already a low ground between hills. He had the area dozed out for a deep pond, with narrow edging which dropped deep just a short ways in. After it was filled it was stocked, but nothing was caught out of it.
He died when I was very little. Grandma was still trying to fish something out of it. Her efforts caused me to fantasize some giant cats hugging the bottom of that very deep pond.
Sometimes I would sit and stare at those bobbing jugs, waiting for one to suddenly jerk under.

I’m not asking about saving an empty container and using it for another purpose. I mean refill:
– Bottled water from a 2½-gallon jug into a personal-size water bottle such as a 16.9-oz. Crystal Geyser bottle.
– Fruit juice from a large bottle into a single-serving bottle of the same kind of fruit juice.
– Detergent from a big jug into a smaller, lighter bottle of detergent.
– Tylenol from a large container into a small purse-size bottle of Tylenol.

I do all of those. The container still has in it what it says on the label, but it’s not the original contents—it’s been refilled from a larger supply.

Oh, OK. Yeah, I do all that, too. I buy stuff in bulk and transfer to smaller things all the time.
Costco is your friend. :-)

I actually put zip loc bags in the washing machine inside out then prop them onto something to dry. I love the ones with the real zipper but they’re expensive.

The toothpaste I like has screw on cap. I saved “flip top” toothpaste caps and run them through the dishwasher to use in place of the screw on top.