The sponge is so hard that it won't absorb water very fast. I had to squeeze and press on it for a few minutes to get it loose enough to absorb the water. It hasn't fully dried yet so I don't know if this process will need to be repeated every time it needs water. If so then I would lower my rating. I'm not using distilled water because I am not spending money to buy it. These manufacturers should make their sponges anti-microbial and also capable of handling other things such as minerals over time. I have used a different brand that is a tiny bit smaller, has an easier sponge, and has a lid that flips open instead of needing to be removed. I like it better and it costs about the same. Still, this one works as advertised.