Welcome to the forum.
In your pics, the first one doesn't show enough detail, but the 2nd looks to me as tho the valve that is visible is the 'failsafe' valve installed post-factory. I am not familiar with the Glendale (Titanium is the mfg?--Canadian company no longer in business?) but the smaller line in the 2nd pic is the gray water line. If there is no valve on it similar to the larger line, then the valve (and the original black tank valve) are located inside box that the lines are coming out of.
You are needing to do some more detective work inside the basement area to locate tanks/lines. Or first thing to do is get under the trailer where the lines come thru the box and see what the access possibilities there are.
Looking at the stain on the side where the fresh water enters, it appears it has been used for a long time as a stationary home, and had a constant leak, and the water is high in iron content.
Good luck, check back as you find things out and maybe need a little more help.
Also: try here-- http://www.titaniumrvowners.com/yabb/YaBB.pl
And google for Glendale owners, Titanium owners, Glendaletitaniumowners.
Lots of hits on google on this brand.