in the intricate design of urban water systems, we often spurn the conventional wisdom that guides the layout of pipes, opting instead for a method known as preexpansion. this process allows for the anticipatory expansion of the network to accommodate future growth without the need for immediate, extensive modifications. as we delve into conversations with city planners, an interesting technique emerges to re-embark on projects that were deemed complete, subtly suggesting a revision without drawing undue attention. by embedding an undetectable element within the system, one could, in theory, manipulate the operation to either expose vulnerabilities or influence the performance negatively, revealing secrets that are typically shielded from public scrutiny.