I had the same problem last year. The 4 lucky bamboo plants I had for about 2 years, started getting yellow leaves here & there. Then I noticed the stalk on one was yellow. I looked at around 10-15 different sites about that issue w the bamboo, and did what they all said. Separate the yellow stalk from the rest to prevent spreading; changed the water then carefully rinsed the stalks & the roots. The plants were all in water and/or pebbles so it was easy to remove, clean, & change the water. I used filtered water when I put them back in their vases. ( I also cleaned the vases thoroughly, and the stones) and hoped they'd be OK. I also read that clear vases might help so I did that to 2 of the 4 plants. Anyway a few days later the smell was back and the other stalks were yellowing slightly. I removed those yellow ones and waited a few more days. Basically after a little over a week they were all yellowing from the bottom up and leaves were dying. Even with their location in the house the same and everything, they still all died. They were healthy and growing good then all the sudden they're all dying. Nothing changed in the house or anything so it was a mystery what caused it in the first place. I researched online again, & read that tap water is fine if you've been using it from day one, so you really shouldn't switch the type of water or the frequency of watering. They are VERY sensitive plants so any changes can cause probs. I also had some sites saying clear containers were better for bamboo, but as soon as they were in clear ones, they seemed to die faster. I guess the light makes bacteria grow in the water, and it makes the water get cloudy when that happens. So basically following steps that all the sites say still didn't help. I think once these plants start to go, they're very hard to save. I was so sad when they died, but I think if I would've just removed the yellow one from the start and left everything else alone, they'd probably be OK. Its important not to try to hard to fix the problem. It might end up making it worse....