There is no standard requirement for iodine value of pure water, but the higher the iodine value, the higher the removal rate of residual chlorine. As for the effect on iodine value in water, I checked and found no relevant information. According to experience, the impact should be small.

The following figure shows the change of iodine value of activated carbon with the use time.

In other words, producing water now requires activated carbon, which is safer than drinking tap water.