Fresh water tank keeps draining via overfill tube?!

[2022enlighten18bh]

When I fill my fresh water tank the overfill line drains?!

What is missing?

Is there a valve behind a service panel?

[muleman]

That is a total new one on me but has to be a check valve somewhere not working or missing will do some studying but am anxious to hear anyone with answers! Good luck ��

[muleman]

What is your camper?

[2022enlighten18bh]

Originally Posted by muleman

That is a total new one on me but has to be a check valve somewhere not working or missing will do some studying but am anxious to hear anyone with answers! Good luck ��

It was just a valve I had to find under the bunk mattress

[muleman]

Good deal safe travels.