If I knew that I could accurately predict a shortage of drinking water in ten years, the ideal thing to do would be to bottle the water now, and sell when the shortage occurs (buy low, sell high…) So a “few bucks” as you say, can get you a 24 pack of bottled water now, then sell them for x dollars a piece later when the shortage occurs (supply and demand).
Now if you’re looking for a water index fund or such, well I don’t know about that.
But investing in bottled water companies might not be a good idea. When the aliens start sucking up our water, the water companies are going to lose the water. There might be some water companies that make fortunes, but other water companies that go bankrupt, depending on which water companies lose their supply.
And of course, the vast majority of water is not used for drinking, but for agriculture and industry. So a “water shortage” doesn’t mean people go thirsty, it means we won’t be able to pump as many acre-feet onto our crops. So you’d be smarter to invest in drought tolerant agricultural products instead.
In 1999, the EPA lowered the Arsenic limit from 50 ppb to 10 ppb, municipalities had 'til 2005 to comply. Many applied for, and were granted extensions. Those extensions are due to expire in the near future.
There are a number of companies that make arsenic mitigation systems. More companies specialize in the installation of such. These may represent investment opportunities…or not…consult your investment adviser.
Disclosure: I am employed by a producer of equipment for mitigation of arsenic in drinking water. This is a privately held company, not currently seeking new investment.