Have never seen anybody other than sellers/makers of the grapefruit stuff claim it can treat contaminated water (am unaware of any peer-reviewed scientific studies) so I assume one can get the same result by squeezing oil from a handy snake.

Iodine isn't the best chemical treatment for biological contamination; chlorine dioxide is considerably more effective. The place I'd start, in any case, is first determining what contamination is in the water, then matching it with the best treatment, whether chemical, filtration, UV, etc.

Good luck,