Chemical methods use toxic chemicals such as chlorine to kill pathogens in the water. They do not remove particulate matter, and some pathogens my remain protected within particles.

Radiation affects cells in 4 ways:

• Genetic material is destroyed, and the cell can't reproduce.
• Genetic material is destroyed and the cell does not produce viable offspring.
• Genetic material is destroyed and the cell dies.
• Genetic material is destroyed and the cell produces mutant offspring (super-rare).

People walk out in the sun, get hit by radiation, and the top 3 things happen all the time. It doesn't matter because we have a lot of cells and the extras will pick up the slack. Sometimes radiation destroys DNA in such a way that the cell produces mutant cells. Most of the time these cells can't reproduce. In rare cases those cells are cancerous.

However, for single cell organisms, radiation is ends them. Most pathogens in water are single cell, so expose the water to enough radiation, and most of the pathogens won't be able to do anything harmful. Those left over will get taken care of by your digestive system. In order for a pathogen to make you sick, it must be present in significant numbers and also be able to quickly reproduce in your body. A bunch of sterile pathogens will just get digested.

Will radiation make mutant super-pathogens?

• No. Radiation destroys genetic information. In cancer, it destroys the cell's reproductive off switch. Say this happened in the water pathogens. The cell is on it's own in the water. No nutrients, no friends nearby. Then, more radiation. Chances are it would get hit again and most likely it would not be made more viable. What happens when you take a statistical slim chance (mutation causing DNA hit) multiply it by another slim chance (that hit causes a desirable change), then multiply it by the chances that it won't get irradiated in a bad way, and then hope that happens for the next 20 or so iterations so the pathogen can become dangerous? You get a statistical impossibility. So, unless God wants you dead from super-dysentery, you're safe.

The SteriPen makes water safe to drink by exposing it to UV radiation.

• Quick: 90 seconds per Liter
• Taste and Chemical Free

• Batteries need to be replaced often
• Does not filter particulate

The sun is a huge source of radiation in all forms. Water exposed to sunlight will be exposed to pathogen-killing radiation.

• Low Cost

• Dependent of intensity of sunshine
• Takes a long time
• Requires proper plastic bottles