"The fine folks from The Gerlach GID (General Improvement District) write to let us know they'll be selling water to Burning Man participants this year"
From one report I found online it looks like Gerlach has about 400K of water in reserve. Assuming each person uses about 1.5 gallons of water a day, and that they stay out there for seven days, you could provide water for about 38K of people (roughly 4/5 the size of the population depending on the year). I've never seen a graph showing the size of the city each day, if one existed publicly you could compute the actual usage for the population since there are a lot of people who aren't in black rock city for the entire time.
Less gas, less plastic containers, and less transport cost.
One of the things I am wondering about is what the water recharge rate is for Gerlach. From the USGS maps it looks like the water table should be at ±20 feet, but it is hard to say with certainty because they are near the mountains (aka the alluvial fans might change all of this). If the recharge rate is small then it would be possible to create a "drought" for the city if every burner purchased their water from Gerlach, that is until the next rains occur or the system just trickles back up to capacity. No water would also mean no fire fighting capability.
What is Gerlach's water processing capacity, and what the wear/tear on the system itself? It could be that one year of burning man usage generates a cash flow that causes some sort of long term cost hike because of equipment replacement. Gerlach I assume will also just cut off the water when their water supply drops to a certain point, leaving a number of people with no water (high and dry?). I've not been able to find anything online showing the design of their water purification plant. It would be good to know what their capacity for water filtration is, rate of recharge, and cost of water based on kilowatt per hour. I assume the city doesn't do water treatment for used water. Septic systems I would think make sense with the population of Gerlach being just 150 people.
On a different side of the coin, a lot of burners just carry jugs of water as well, dealing with hundreds of gallons of water is a different problem all together (bring iodine pellets!). I wouldn't trust everyone to know how to handle water, even if it was just for a week.
If it turns out that Gerlach can handle the water requirements, you would think it would make sense to increase the total amount of water storage and fill additional storage during the rainy season when I would think that water is more plentiful. The basic cost of potable water storage containment is about $1 per gallon of storage. This is an area of where an investment in the $1 million range would go a long way.
In Seattle I can buy potable 50gallon water containers for around $26. My camp is about ~40 people, so if we picked up just the water for the kitchen/showers we could save quite a bit on our water costs (I estimate our water usage at 2 gallons a day, which is high, but I prefer to have a little too much). Last year we acquired 400 gallons of water, and additional personal containers brought our entire water supply up to a little above 500 gallons of water. We had about 100 gallons of spare water at the end of the week.
It is pretty cool to see the city make some additional money off the event. I would love to see water become a bit "greener" for the event.
Disclaimer: I've not been a practicing geologist/geo-science/water planning type in more then a decade, so my information could be quite off.