Uva germicidal device

A fluid purification system comprising:

• a treatment vessel configured to contain a fluid to be purified;
• at least one source of ultraviolet radiation with at least 50% of its emitted spectral energy at wavelengths between 315 nm and 400 nm, positioned exterior to said treatment vessel;
• and
• at least one portion of at least one wall of said treatment vessel that is substantially transparent to the ultraviolet radiation emitted by said at least one source of ultraviolet radiation, located so that at least 50% of said ultraviolet radiation propagates through said at least one substantially transparent portion of said at least one wall and is configured to propagate into fluid to be treated within the vessel for the purpose of killing or disabling pathogenic microorganisms in the fluid.