Question
Dear Jeff and Jacob,

 I have a cape sundew collection coming and I have collected rain water.
However, the rain water is yellow . Is this water safe to use and do you know why it's yellow?

         Sincerely,
         David

Answer
There are many reasons why water is yellow, but without knowing anything about your environment and collection system, I can't speculate what is causing it.  It's best to be safe than sorry, so avoid using the water at this time.  Clean out the barrel or bucket.  Use a mild sanitizer and rinse thoroughly.  If you're collecting rainwater from your roof and gutters, you may need to use a different system of collection since the roof and gutters may be adding contaminants to your water.

Good growing!
Jacob Farin