While the number of people living in Waikato's main centre will rise over the next 50 years, smaller centres will need to fight to retain their numbers.
A university study has found the Waikato region could grow by 175,000 people by 2063, but some spots will lose numbers.
Projections outlined in a report by the University of Waikato indicate the region is set to grow by about 40 per cent between 2013 and 2063 to grow from 425,000 to more than 600,000 people over 50 years.
The region's people would be increasingly elderly, the report said.
Much of the growth in regional numbers would come in urban populations and be centred mainly in Hamilton, Waikato and Waipa districts, according to the university's National Institute of Demographic and Environmental Analysis (NIDEA).
Service towns are predicted to decline in numbers over the same period, which will have a flow-on effect to their ratepayers, the report said.
After initial growth, Otorohanga and Thames-Coromandel would see a drop in population, while Waitomo and South Waikato would slowly decline from now to 2063, the report said.
"In areas of declining and ageing population in rural towns and communities it will be increasingly difficult to provide adequate infrastructure and services at an affordable cost to the ratepayers."
Changing life expectancy rates in 2043 compared to 2013 were also examined. Otorohanga - which already has the longest life expectancy in the region - was projected to rise the most with males expected to live to 86 and females to 89 by 2043.
To keep young people in the region it would be important to invest in youth to ensure they have the right skills and to provide attractive work opportunities, the report said.
Hamilton will increase its share of the region's population from about 35 per cent to almost 44 per cent over the 50 years.
Demographic changes would throw up a range of challenges as communities work out how to respond to the needs and opportunities of an ageing population, and regions on the decline fight to promote themselves as an attractive place to live and work.
Population growth generally would increase demand for a range of services and infrastructure, particularly transport systems and public services, such as for health, social services and education.
There would also be more pressure on limited resources such as water and high quality soil, particularly in and around Hamilton, while housing costs would rise in high demand areas.
The report, commissioned by Waikato Regional Council, was presented to its Strategy and Policy Committee on Tuesday.
The information would play a key role in planning by regional, city and district councils in the region, said council's principal strategic adviser Dr Beat Huser.
"Knowing and understanding how and where demographic changes occur will be critical when it comes to meeting the needs of our future communities," Huser said.
The data in the Waikato Population Projections study, which will be used in a wide range of planning documents, is due to be updated in 2019.
Image: Chris Hillock