Reusing everyday items instead of purchasing them for single use is an amazing way of reducing waste. Owning a reusable water bottle that you refill reduces the amount of waste traveling into the waste stream. When you reuse, you are not continually buying plastic water bottles that are then thrown away. In the same way, having reusable bags reduces the number of plastic bags that end up in landfills.
On top of reducing waste, reusing also conserve energy and resources which helps to reduce your overall carbon footprint.