I have a French butter dish. Last week I had a problem with it. The butter fell into the water. I washed it, air dried it thoroughly and refilled it with butter and water. The next day the butter had fallen into the water again. I am mystified. Please help me.

You possibly didn't have the butter packed into it tightly enough.

Or it was in the sun or exposed to heat causing the water to heat up and the butter to melt slightly.

Yes the problem is that you didn't press the butter in or it was too cold when you put it in. We make butter dishes and occasionally this is a problem. Let the butter warm a bit out of the fridge, then press it in with the back of a spoon. No need to fill it all the way... just as muck as you'll use in a week or so.
Tom at Clay Coyote Pottery