Mitigating water scarcity has proven to be a tricky political subject because, in many countries, environmental or climate solutions tend to have a hard time gathering enough political support to become a reality.
It is also extremely expensive to build out new water supplies, dams and desalination plants.
"Unless there is an acute event — a severe drought for example — it is the [political] constraints that play out in a long time frame," Keller said.
Consequently, many governments have done little to guide their citizens on water-efficient behavior. That can be implemented through price controls, Otto said, but it's rarely a popular measure.
"There should be two tiers of pricing. Conservation pricing, which charges the minimum amount for water that is sufficient for basic needs, should be provided at low rates. Discretionary water use, which is anything beyond the necessary amount, should be charged more," Otto said.
On a national level, she said, governments should encourage conversation about conservation issues. That is, saving water will always be cheaper than building or drilling for new sources, Otto added.
The good news, experts said, is there will be time for governments to start preparing for a Day Zero scenario.
"It's not going to be a surprise. The city is not going to run out of water suddenly," Keller said.