NZ home insurance typically covers sudden accidental damage to a hot water cylinder — such as an unexpected burst — but not gradual deterioration, wear and tear, or age-related failure. Check your policy's specific wording, as coverage varies between insurers.
They typically do NOT cover: age-related failure, gradual corrosion, or maintenance issues you should have addressed earlier.
If your cylinder was damaged in the 2010–2011 Canterbury earthquakes and you haven't had a full settlement, EQC claims are handled separately. If earthquake damage may have contributed to current cylinder problems, speak to your insurer.