So I'm seeing a lot of people posting problems with their lucky bamboos grown in water.

The main problem is that the water is turning stagnant, the roots suffocate and die. Like fishes, most roots need oxygen from the water.
Other problems include harmful microbes that love stagnant water.

I used to simply change water every 3 days, but if I got lazy my LB would very quickly get yellow leaves. Hydrogen peroxide helped a bit, as did oxygen releasing rocks but certain LB individuals on my window sill still didn't respond well.

In the end I decided to go with a passive hydroponics system:

http://scienceinhydroponics.com/2010/08/completely-passive-non-recirculating-hydroponic-systems-yes-its-possible.html

http://forums.gardenweb.com/forums/load/hydro/msg0605193532480.html?2

http://imgur.com/a/s2eqM

I just try to maintain the water at roughly the same level, add a few sips every few days. Gone a few weeks with this set up before posting and everything seems like it's going well.