Toddler-proof your Fridge's Water Dispenser

As frequent readers already know (all four of them!), we have a real spitfire of an 18-month-old on our hands just now. She has incredibly strong opinions about everything from food to footwear, Loves to mimic her parents and older siblings, and is absolutely impervious to any amount of shouted "No's", scolding, or any other means of getting her attention when she's decided on a course of action. (I know, shouting never works. Sorry. I seem to keep doing it anyway!)

The last month or three she's decided that she wants nothing to do with sippy cups. No, she wants her water in an open cup. To her credit, she often spills only a little when she's paying attention, but the problem is when she's done. Not willing to let the fun end, she proceeds to dump the remaining water on the nearest surface, then play in the mess.
Even more recently, she's discovered that she can, with the proper vessel, reach and activate the water dispenser in the refrigerator door. (Which does not, needless to say, have any sort of a child lock. I checked. Twice!) A couple of days ago I'd left her unsupervised for 10 minutes or so (bad Mommy!), and when I came down to investigate the suspicious quiet, found that she'd been repeatedly filling up a tiny paper cup, walking across two rooms, and then pouring the contents on the kid table in the living room.
It was my final straw: I went looking for some cardboard and duct tape, and soon my fridge door looked like this:

"But Mommy, how will we get water?!" whined my eldest.  "You'll have to walk down to the bathroom," I replied. "How will we get ice, though?!" he demanded. "Well, you won't. You don't really need it anyway," I answered, perhaps a tad crossly.

Less than 24 hours later, however, the whole question was moot: the baby found removing the whole assembly a trivial task - not to mention one that made a Great ripping noise! - and we were back to square one.
Yes, I could have used 3x as much duct tape and probably prevented her getting it loose. But the fact was, everyone in the household is really used to getting their beverages from that dispenser, and I didn't want to give it up.

Googling for solutions didn't really turn up much, at least on the commercial side of things. I did find a discussion board in which a parent suggested using a block or other object to temporarily disable the lever.  Since most of the other responses could be grouped into one of two unrealistic or untenable categories (1. Teach your kid not to do it, and 2. Disconnect it at the back and drain the hose), I was interested.

I cast about in my kitchen for a likely object, and picked up this plastic lid from an empty peanut butter jar:

Not really expecting much, I fiddled around with the dispenser, and found that it could just hang off the back of the lever like this: 

To my delight I found that it effectively disables the lever, and yet can be easily removed and replaced by a competent adult.

Our baby isn't tall enough to reach this high, so unless she finds a step stool (we try to keep them hidden and away from the kitchen already!), she'd not going to be able to get past it.
The other two kids are probably going to find it a bit of a challenge - especially putting it Back - but I intend to train them to get me if they're unable to put things back the way they found them.  Or they can always get their water from the bathroom.  :-)

Now, a couple of quick notes before you run off to pilfer a lid:

• This lid has a fairly deep lip. I don't think a metal lid such as the kind that come on a commercial glass jar would work. I tried using the metal rim from a Mason jar alone, but it is in fact the solid part of the lid that stops the lever from being depressed. While it is deep enough to hang on, you'd have to use rim and lid in conjunction. 
• I am assuming that my dispenser's design is reasonably standard, but have no simple way of testing this. So your millage may vary. (In fact, this does Not work on my parents' older fridge.)

Hey, if it Doesn't work for you - and better yet, if you have a solution of your own! - let me know in a comment!
Just don't tell me to  teach my kid to leave it alone. I've tried that. I AM trying that. Really! But I need a mechanical solution in the interim, and you may too!

UPDATE: This post is from October. By early December my incredibly intelligent now 20-month-old had figured out how to remove the "lock" - a trick that actually still often defeats her four-year-old sister.
I am milking a few more weeks or months out of the solution by using a lid from a vitamin bottle. It's just as deep as the peanut butter lid, but only about 1/2 the diameter. This extra inch or so puts it out of her reach, for now!
Now, if only she'd use her powers for good rather than evil... :)