The longest dry fast I completed was 9.5 days, during which time I did not have any contact with water except for washing hands after the bathroom. If I had to clean dished I would wear rubber gloves. My prior fasts of shorter length I follow the same rule.
According to Dr. Filonov, a russian medical doctor who has been specializing in dry fasting for over 20 years, the main impact of contact with water during the dry fast is that the are of contact will undergo less rejuvenation then the rest of the body. My assumption that it's because your skin sponges water in during the dry fast and therefor gets impacted on the cellular level by feeling the cells with water.
Currently I am preparing for an 11 day dry fast by fasting for 18 hours per day. The difference is that this time i do allow myself to take a shower because the length is not significant enough to make an impact.