Hey Kevin,
From what I have read, chlorine can burn off pretty quickly whereas chloramine is much more stable.
The Jordan Valley Water quality Report for 2011 states the avg chlorine reading was .5 mg/l or 0.500571152 PPM with a maximum reading topping out at 1.5 mg/l or 1.501713455PPM.
The fact that you are running a drip is why are able to get away with not treating your water. If you were to do a big 50% water change all at once when your municipality happened to increase chlorine levels to 1.5 mg/l, you would probably have some losses, or at the very least, negative effects. But since you are introducing small amounts of water to your system relatively slowly, it is likely burning off before it becomes toxic.
I'm not so sure you would be able to do this if your treatment plant used chloramine.
+1 for using Seachem Safe (powered version of Prime).
I bought 1 Kilo for $40, which will treat 200,000 gallons. That comes out to $0.02 per 100 gallons of water treated. It's cheap insurance for those of us with water treated with chloramine or who have chlorinated water but do not run drip systems.
Not sure how much truth there is to this, but apparently running a UV will also help to remove both chlorine and chloramine:
http://uvsciences.com/chlorine.html