Science Buddies: "Ask an Expert"

Hi,

I am an eighth grader participating in a science fair at my school. My project has to do with water disinfection. I have not been able to find how long to leave it under the light. I hope you are able to answer my question of how long to leave my water under the uv light. Here is some background information on my project:
I will be using a 15 watt germicidal light with 254 nm wave lengths. Also the water I will be disinfecting will be in a 3/4 filled 16 oz. water bottle. The water will also be water from a local creek and I am planning to have the light about a foot and a half above the bottle.

you could try putting it in a box? I am doing a similar project with bread and am building a container with my dad

Hi cjones02,

It depends on the contamination level, but approximately 30-60 minutes should be enough.

Peter S.