Your unvented water cylinder will deteriorate over time due to wear and strain. Even steel can deteriorate over time. Every year, you should get your unvented cylinder annual inspection to keep an eye out for any potential damage and maintain the cylinder's build. This enables you to get the most out of your investment and have continuous access to hot water at the faucets. Even a relatively minor leak can result in structural damage to your property because corrosion at intake and outlet connections can be problematic.