[VAC] Re: Water Tank Cap <- way to secure?

[Dave Huffman <huff@xxxxxxxxxxxx>]

I just remembered another Stream concern on my Malheur Oregon trip.
On the way out I partly filled the water tank, knowing I was heading
north to the campground with NO water.  I was in no hurry and thought to
have thoroughly walked around and checked ALL ready-to-tow matters.
    Luckily I stopped to re-check everything before getting on the
highway to head north.  The capless water spout stared at me like a
Fearless Fosdick wound ('Lil Abner).  Oh God, I have read fruitless
search reports for Stream Water Tank Caps on this list!  The field
station was only 5 miles back, so I turned around and headed back.  I
had heard a minimal scrap sound as I pulled the trailer out of the rough
road camping area, though I had checked and found nothing.  I had left
the cap on the electric jack top and I hoped it had fallen off either
immediately at the camping area, or on the pot-holed gravel roads there.

    It was not where I pulled the trailer out, where it should have
fallen off as the trailer cleared a bumpy, steep, angled pull onto the
road.  But it was sitting right in the middle of the field station
gravel road about 1/4 mile away.  It was 1:30 PM in the desert heat (a
hot spell had been in for 4 days), but on my way back to the Stream, I
encountered a fellow RVer walking along the field station road.  He had
seen me park and walk the road, obviously searching for something.  So
he just got out to help!
    So my question: ANY REASONALBLE WAY TO MOUNT A CHAIN TO THE WATER
CAP?  If I simply drill a hole in the cap, is that cap necessary to seal
the pressure for the tank?  Or is there a valve lower down?
    Obviously I shall include the water cap on my check list from now
on.  But I like the idea that it can't get very far when I do have it
off.

Huff