New toyhauler owner question

Been RV'ing for over 30 years so not a rookie when it comes to how they work. I bought a 19FK Eclipse and didn't get any manuals with it. I'm trying to find the FW drain. I was told it's under the trailer on the bottom of the FW tank. All I see is a inch and a half female fitting with a square plug in it, when I remove it nothing, if you put your finger in there it's solid, like the drain valve was never put in. Other than that there is no other spot that looks like a drain. Can anybody help me find the FW drain.