What is a common issue with old galvanized plumbing systems?

Old galvanized plumbing systems often suffer from rust and mineral buildup, which is a direct result of corrosion over time. Galvanized pipes are coated with a layer of zinc to help prevent rusting; however, as the pipes age, this protective layer deteriorates. This corrosion leads to the formation of rust on the inside of the pipes, which can flake off and combine with sediment and mineral deposits in the water.

As rust and minerals accumulate, they restrict the internal diameter of the pipes, leading to reduced water flow and potentially causing water pressure issues. This buildup can also result in discoloration or unpleasant taste in the water, further impacting the system's performance.

In contrast, the other options suggest improvements or benefits that do not apply to aging galvanized systems. For instance, old galvanized pipes do not typically result in improved water pressure or clarity, nor do they possess increased resistance to corrosion as they age. Additionally, their compatibility with modern fixtures is often poor, as newer systems generally use materials that provide better performance and longevity. Therefore, the primary concern with aging galvanized plumbing is the rust and mineral buildup that significantly hampers functionality.