It really doesn't leak! After 4-5 uses, we broke the lid. At first, we bought it to put water in, but I also put natural juice in it twice and the straw immediately turned yellow, no matter how much I washed it, it doesn't clean. Another thing it needs is to definitely buy the brushes from the same company to clean the straw! I bought ones from another company that I found more affordable and regretted it, they don't reach the bottom and don't fit in the ball at the end of the straw, so yes, it needs its own brushes and if you also put a lot of things other than water, it needs a thorough cleaning