I have traveled to many places in the world where water is scarce.
I am also a hot weather person, and much prefer to travel in Summer versus Winter, so I have been in very hot climates, and I have a good tolerance for heat.
Unfortunately, recent data from some climate officials show that overall the climate is getting hotter across the Earth, especially in Europe.
If the government does not make decisions to enforce reduced usage, then there are some people who will pay no attention to climate issues. For example, in wealthy Beverly Hills, California, the millionaires will simply pay more to keep their gardens watered, not necessarily limit usage to help others. Unfortunately, even mandatory conservation restrictions there were reduced due to all the pushback from diverse businesses, politicians, etc.
It is not realistic to tell people to stay home and not be tourists just by the goodness of their hearts, especially if there are no official announcements or recommendations. Water efficiency should not be a hit-or-miss effort, but rather a comprehensive strategic plan phased in on many fronts over multiple years. Water has become one of the most valuable commodities in many places, and European cities may have to learn lessons from other countries that have managed for decades with limited water. For example, Morocco is creating desalination plants across the country.
Some people, like me, reserved their trip to Barcelona two years in advance and cannot change or cancel. Others may be of an age where they might never be able to return again to visit. Yes, I am reducing my time greatly in the city this year--just basically a pass-through, but I have visited before, so I am not too upset. Those who planned Barcelona beach vacations with swimming pools may be very disappointed, however.
I completely support efforts to reduce overwhelming visitor numbers, but local citizens have to elect officials who will make the changes desired. Of course, those who benefit from tourism will be against losing their incomes.
This is a worldwide issue as our human population has climbed, more people are traveling after the pandemic, and earnings have increased in many countries. I do not necessarily think it is fair to just limit tourism to those who spend the most, although I do see that happening in many places. Perhaps someday we will even see a lottery system for travel!