World overpopulation

You could be right about food.
Water I dont know enough about to comment.

Jobs - people have been coming off the land for the last 50 or 60 years due to increased technology.

Room - where? Which countries exactly?
A lot of the world is inhospitable, and is not lived on for a reason.

Crun has made a very sensible point.

There is probably quite enough water for us if it were managed properly by individuals and corporations. However it is often in the "wrong places" for populations.

In places like Africa many years of rich western european colonisation has forced the native Africans out of the most fertile water secure parts of Africa into the drier less fertile parts of the country.
"We" (the developed world) squander billions of gallons of water in our daily household use, too many long high volume shower's, too many deep baths! Washing all clothes and towels daily. Never mind filling swimming pools, watering our gardens golf courses, parks etc etc.

Poorer countries do not have the money to build good safe water supply infrastructures. Then there are political problems with rivers that cross many different countries and who takes how much water from which particiular parts of it.
Then there are companies like Coca Cola owning springs and wells in poorer countries to produce their drinks and companies like Nestle buying up springs for them to sell us expensive bottled water.

The big problem is not in fact the population increase, as there are indications that birth rates are slowing down, but the increasing age of populations and the resulting effects upon society. Interestingly immigration slows down the projected rate of age increase because immigrants seem to have more children. With huge numbers of elderly people, some needing extra care it can be argued that more children are needed to provide the necessary support. longevity-science.org/Population_Aging.htm

"With huge numbers of elderly people, some needing extra care it can be argued that more children are needed to provide the necessary support."

No it can't. It's not possible to achieve a sustained reduction in the average age by increasing the birth rate.

Imagine we start with a birth rate of 2 babies per woman and a stable population, and then increase the birth rate to 2.5 BPW. At first there will be a reduction in the average age, but babies grow up, by which time you will be left with the same average age you started with and a population that's now growing out of control because you increased the BR. If you want to maintain the lower average age you now have to increase the BR again and again, with the population escalating at ever faster and faster rates.

The converse is true as well of course. Although most of the increase in age is due to longevity, some of it will be due to the recent reductions in the birth rate, but just as before, that will only be temporary as the change works it's way through the system.

Nothing to do with the reducing the average age but with providing the necessary infrastructure to support society. If as predicted the percentage of people over 65 increases to almost 30% that is almost 1 in 3 people who are approaching retirement, or already retired. If you consider that there is also likely to be a large number of these older people requiring medical help and support and smaller numbers of young people working and making tax contributions it will be impossible to maintain the same standards of care we are used to.

Agreed, but I thought you were trying to argue that a higher birth rate among immigrants would alleviate the problem.

"....it will be impossible to maintain the same standards of care we are used to"

...or the same living standards.