You will find lots of other useful information on the government's Get Ready website 

Eg storing drinking water for emergencies https://getready.govt.nz/prepared/household/supplies/storing-water

Red Cross has useful info also https://www.redcross.org.nz/get-help/emergencies-and-disasters/prepare-for-a-disaster-get-good-and-ready#step_1

PNCC Emergency Hub page https://www.pncc.govt.nz/Services/Emergencies