The product does what it's meant to do. There's probably a small margin for this type of product to be GREAT. However I rate it as 3 starts because it could be better. For starters it takes about 10 min for the chemicals to fully react before you can put them into the water, which if you're out on the go on the countryside perhaps is a long wait. Also, it leaves a strong smell and taste of phosphorous (which is one of the reaction components) in the water, and colours the water a bit yellowish. It's not a big deal and for me, but I can imagine small children being discouraged by the smell and taste of it and so, if you can buy a different presentation (tablets) it's perhaps more convenient.