The chance of Wellington experiencing an acute water shortage this summer has increased, while emergency water tanks sell out around the region.

New modelling from Wellington Water shows there is now a 33 percent chance of the region seeing an acute water shortage rather than a 24 percent chance that had been previously recorded.

Under that type of shortage, level 4 water restrictions would be brought into place which would ban all outdoor water use and reduce indoor water use by up to 50 percent.