I was asked the following:

The MCC coach has a large fresh water tank, but we have been unable to find the filler neck??

anyone know?

My MCC is still at MCR waiting for certain requests to be carried out....which will be done in rotation with their busy schedule...;(

Most coaches have a fresh water inlet, but do not have a filler neck per say. Do you have a fresh water inlet, looks like a garden hose end?

When you hook this up, there is usually a switch to either fill your tank, or just have it go straight through to you domestic water lines.

Doug, It may be an "Auto Fill" Look for a switch labeled as such. You must be connected to city water, then switch it on, when the tank is full it will beep and shut the water off. Our Sovereign does not have a potable water fill either.

Ours came with a city water fill on the dirver side, and a gravity fill on the pass side. The gravity fill was behind a white plastic door.

I did away with the gravity fill. We either pressure fill or the coach's pump sucks from a portable container.

As Corey said look for what looks like a garden hose connection.
On my 1985 Barth Regency I have two of them located on the left side of the coach.
The one located near the front is to fill the fresh water tanks. The one located near the rear is to hook up to a water connection at a campground. My Barth does have a switch on the inside panel for auto fill, however it does not work and somewhere along the different owners this feature has been removed.

Hope this helps,
Jim

1985 Barth Regency MCC
35 ft 8.2 Detroit 225hp
Allison 4 speed