Clearwell is the village in which I live, and it has a well and a little brook which I think is Thurstans brook. The water is quite clear and you would be forgiven for thinking that is how this village got its name.
However on old maps it is marked as Clowerwell and once it was called Wellington. The name Wellington means “the place of the spring” then it became Clowerwell meaning “spring among the clover” so that is how Clearwell is derived. Nothing to do with the purity of the water.