I think I’ve sort of got how this 100 gallon thing may work now, very slightly sneaky tbh (bear with me if I messed this up horribly or concluded something illogical with all the approximation, btw).
Assuming we’re talking 100 UK gallons since Life UK Limited is, by title, a UK company, that approximately equal to 455 liters. In both the tweet and image, it is notable that the wording is that this will be given to “someone” in need. This wording may have been used to intentionally get people to believe that this amount is given individually, one-time per person, thus encouraging them to like/RT to help a tremendous amount of people (1 million+). However, Life UK’s mission statement provides: “every bottle gives at least 1000 litres of clean drinking #water to a community in need”. So, of note: a like/RT counts as less than half of the usual bottle purchase donation, and, based upon the implications of the statement, the “someone” is much more likely to be a member of the “community” at large served this amount via a well on a repetitive basis (over 100 gallons over a lifetime), rather than an individual receiving one single serving of 100 gallons of clean water. It’s really not 1 million needy people served 100 gallons of clean water each, but rather more like 1 million servings of 100 gallons of clean water to needy people.
As we all know, Life UK/Drop4Drop provide their water via donated wells. According to financial statements from the 2012-2013 financial period (
http://apps.charitycommission.gov.uk...130331_E_C.pdf), Drop4Drop received £59,621 in “charitable contributions” (of which £11,638 were from Life UK). Drop4Drop then spent a total of £53,308, of which £47,207 was spent on “charitable activities”, i.e. building wells. With these contributions, a total of 36 wells were built during the financial period, 10 of those in Zambia and 26 in Andhra Pradesh. This created a total of 66 wells in Andhra Pradesh, which serve 70,000 people. So, conservatively assuming that all wells costs are roughly equal, and all communities served by one well are of roughly the same size, one well costs £1,311 and serves 1,060 people.
Today, over 1 million people liked/RT’d WWD posts. This means Life UK promised to give 100 million gallons of clean water. An average water well produces at the max 30 gallons of water per minute (I’ve seen anywhere from 3 to 30 gpm being reported). If one well flowed constantly at this very high rate for 1 year, it would produce 15,768,000 gallons of water, and each individual in the 1,060 person community would receive 14,875 gallons during this year. Therefore, in this hypothetical max and constant water flow scenario, in order to meet their promised value of roughly 100 million gallons given in total, Drop4Drop would have to build a total of 6 wells, costing them only £7,986.
While 14,875 gallons per person per year works out to the logical amount of about 40 gallons per person per day (about half of what the average American wastes…err…uses each day), it’s highly unlikely that these wells are all operating 24/7 and releasing at 30gpm. But even one 3gpm well would be able to reach an entire community worth of what was promised here, 100 gallons per serving to every “someone” (for a total of 106,000 gallons served) within only 588 hours of use (24.5 days) of running over its lifetime. In some magical, worst-case-scenario in which every well completely expires after each person in the community had received a 100 gallon serving of water, Drop4Drop would have to build the lofty, albeit perhaps eventually achievable total of 944 wells to reach their 100 million gallons given promise, costing them 26 years of future charitable activity spending at the exact 2012-2013 amount. BUT, since the well will more than likely continue to be usable after each individual has been served 100 gallons, Life UK/Drop4Drop will be technically able to get away with fulfilling its 100 million gallons given promise by providing the same individual multiples of 100 gallon servings via their one community well, with the minimum (under said unlikely, absolutely ideal conditions) total wells being the aforementioned 6.
Anyway, before I convolute this excessive and unnecessary explanation further, in summary:
WWD Donation Promises =
That is the greatest idea EVER. I'm not even kidding! 
