Ok on MOST (Alas not all) motor home look for a square door about on 6-8" square with rounded corners and a lock... Open them and look
Under one of them will be a white plastic cap and often a small vent hole near it.
That's the gravity feed to the fresh water tank (Cap is about 1 inch ID or 1.5 OD)
Follow the hose down to the tank.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times