How issues with sewer resemble enterprise architecture problems

Every now and then I run into trouble with "shared infrastructure" in the real world that resembles my work so much that it would be silly not to write about it. Today it happened again with a clogged sewer line and a service that we have to declog when necessary. See the following diagram for an illustration

The pink/orange block depitcs a row of houses with numbers 1 to 5. The blue blocks are the front yards of each of the houses. When designing these houses in the 1940, a cost saving measure was taken by building a shared infrastructure for sewer lines. The green lines show the sewer lines, the squares are "declogging points", points where the sewer has a small lid where it can be inspected and declogged. The 5 houses have this shared infrastructure with a single access point to the shared main sewer line owned by the city.

Lets assume that I'm living on number 3. This morning I found out the hard way that something was wrong. It could barely be inside the house, as we recently replaces all pipes. Running out and checking the first inspection point showed that the line (indicated in dark red in the diagram) was clogged. This is where it gets interesting.

Years ago we bought a subscription to a declogging service. Paying a small fee per month, these guys are supposed to declog up to the point where the main sewer line is entered. In our case, that's 2 doors down where Street A and Street B intersect. Ouch. That contract doesn't provide for such a circumstance! Time to revisit the architecture of our sewer solution (i.e., consider a dedicated solution, or fix the contract!)

The parallell with enterprise architecture seems obvious. Many organizations make use of some sort of shared services on infrastructure... and run into all sorts of problems. Perhaps I should use this example in training settings!