Is my only option to get rid of trash to burn it? Apart from shipping it out of my city I mean.

Also, what happens when I run out of water? I've placed towers and such on the spots that show water, but they're all going dry. Do they replenish? Is every city destined to just eventually die?

Are you able to purchase water from neighbors in your region?

Theres advanced stuff where you can filter your sewage then put it back in the ground as clean water and place a tower there.

With trash you can collect it and dump it or you can burn it which does create pollution, unsure if theres a "green" way to dispose of it but theres always neighbours if they are willing to collect your garbage for you?

Burn the trash and mine ice from comets and melt it into water with the burning garbage.

As far as water goes, keep in mind that not every city's land plot is going to have access to sufficient water. The region play is critical for filling in those gaps.

Just make a 2nd city on the map, bump up your police force & then send all the trash to city2. Reverse process with the water & send all water from city2 to city1 like in the quick look.

I didn't realize this thread was about SimCity, so I was picturing someone in a really dire situation.

Yes, but only if they're selling. But if they're running into the same kind of depletion I am, they must run out eventually too right?

If I really need to work on a second city to maintain my first one, that's awful =\ Forcing you to depend on others not to bolster, but to actually have a city at all seems like a bad idea.