The title is basically all that I'm asking. How would I go about constructing this to make sure it doesn't break down?
Agitating the water how? Waves or some kind of propeller?
You could have the servo move a bobber up and down to create ripples, or you can get a continuous rotating servo to turn a propeller.
You can also have the servo rotate a weight that vibrates the water container.
Use really high quality redundant parts. It will eventually break down, plan for that.
katkatkattkac:
The title is basically all that I'm asking. How would I go about constructing this to make sure it doesn't break down?
If you just want the water stirred you could use a magnetic stirrer, as used in laboratories.
http://www.newstarenvironmental.com/product/analog-magnetic-stirrer
Shouldn't be too difficult to make one yourself and, as there are no moving parts (apart from the magnet) in contact with the water, it should be long lasting. The stirring magnet should be coated with silicon rubber to protect it.
You haven't told us what sort of agitating motion you need.
You haven't said how fast the agitation needs to be.
You haven't said how long the agitation must operate for.
If you want the agitation to last more than a few minutes - especially if it is fast - I suggest you use a ball-bearing servo.
If you need it to operate for hours at a time I think a DC motor (geared for slow speed is necessary) and a crank (if oscillating motion is required) would be much more suitable.
...R
http://www.newstarenvironmental.com/product/analog-magnetic-stirrer
Shouldn't be too difficult to make one yourself and, as there are no moving parts (apart from the magnet) in contact with the water, it should be long lasting. The stirring magnet should be coated with silicon rubber to protect it.
I want one to stir my Iced tea !
katkatkattkac:
The title is basically all that I'm asking. How would I go about constructing this to make sure it doesn't break down?
all mechanical devices will eventually wear out and break down.
your goal is to select a device and build a contraption that has the least impact on the mechanical device.
the lower the impact on the device, the longer the operational life.
compare a rail road wheel to a car wheel. the rubber on concrete wears much faster than steel on iron.
you did not say if you were stirring or rocking . either way, the selection of your servo needs to not stress any parts.
I'm just curious, your avatar name :
]katkatkatkac
is that the sound Moe make in the Three Stooges when he snaps his fingers with his right hand and pops it with the flat of his left hand ?
raschemmel:
the Three Stooges
I didn't know you were THAT old 
...R
I remember Hop Along Cassidy , The Lone Ranger, Howdy Doody Time, Ripcord, Sky King, Lil Rascals.....
raschemmel:
I remember Hop Along Cassidy , The Lone Ranger, Howdy Doody Time, Ripcord, Sky King, Lil Rascals.....
What size was the screen?
Don
15" black & white I think. I was only 5 or 6 so I don't think I was reading model # labels yet...
floresta:
What size was the screen?
Shouldn't that have been "what shape was the screen?" (round?)
I only saw the 3 Stooges at the Church childrens' Christmas party - projected onto a reasonably white sheet.
No TV in Ireland then.
...R
Three Stooges re-runs :D, im only 24.
raschemmel:
15" black & white I think. I was only 5 or 6 so I don't think I was reading model # labels yet...
We didn't have a TV when Howdy Doody was playing on TV. I had to go to my friends house to watch it on their 7" set. Then I went home, had supper, and went back to watch Captain Video.
Shouldn't that have been "what shape was the screen?" (round?)
The tube was round but the bezel was masked off into a rectangle.
Don
dave-in-nj:
http://www.newstarenvironmental.com/product/analog-magnetic-stirrer
Shouldn't be too difficult to make one yourself and, as there are no moving parts (apart from the magnet) in contact with the water, it should be long lasting. The stirring magnet should be coated with silicon rubber to protect it.I want one to stir my Iced tea !
Do it yourself! 
katkatkattkac:
The title is basically all that I'm asking. How would I go about constructing this to make sure it doesn't break down?
Perhaps you could hold the servo by its attached wires and dip it in and out of the water like a teabag.
When Ben Heck was agitating his PCB etching solution he installed video game controller rumble pack motors to the container they were not even submerged, they were on the outside of the container.... seemed to work pretty well and they are easy to find.