Well its your call, but here is my two cents.....

You are talking about 7 parts per trillion over the limit, and less than half the old limit.

If you look around research seems to suggest that 600 ug/L might cause cancer.

http://socrates.berkeley.edu/~asrg/highlights.html

PPB = Parts per Billion = ng/g = ng/ml.

So at 17 ppb you are 17 nano-grams/ml, or 17 ug/L.
So you are 35 times lower than the level which may cause cancer....

I would worry about being struck by lightning, or a car wreck, or heart deases way ahead of that water.

A simple under the sink RO water filter for a couple hundred bucks would solve the problem.

Fred