Fresh Water Tank

[rick in indiana]

I just recently purchased a 2018 Thor Industries Gemini 24TF and when I fill the fresh water tank it just leaks out through the overflow valve. Does anyone know where I can find the "switch" to stop this from leaking out all the water I fill it with. I have the Mercedes chassis with the full slide on the side.

[16ACE27]

Overflow valve? How about drain valve? Find the drain valve and close it. The overflow is right next to the fill: