Who Pays the Bill?

A condo owner decides to have work done on his bathroom. This is a generally normal thing to happen in a metropolitan area.

Said condo owner contacts the home owners' association, obtains all the various permissions and okays and licenses and permits, and has the work done.

In the process of this work, a plumber comes out to work on the condo's bathroom's pipes. To do said work, said plumber needs to turn off water to said condo.

Turns out, water to said condo is connected with water to another dozen or so units in the building. This isn't a difficulty. All the owners and occupants of said dozen condos are informed water will be turned off for their condos during a specified amount of time, with the expectation that water will be restored afterward.

All good so far.

The plumber who comes out is a new plumber. To facilitate and ease the water disruption, a member of the home owners' association board of directors meets with said plumber, and instructs him which valves are the correct ones to manipulate.

For reasons known only to said plumber, but speculated by all who hear this tale, said plumber disregards the information he has received from the member of the board of directors, who, incidentally, had been living in the condo for many, many years, and knows the building far better than said new plumber, and turns off an incorrect valve in addition to the correct valve. Upon finishing the work in the condo, said plumber does not turn on the incorrect valve he turned off. He does turn on the correct valve he had previously turned off.

Progress to the next morning, when the home owners' association property management company is accepting phone calls. In particular, phone calls from condo occupants who lack water, as the plumber has, recall, not turned on the incorrect valve he turned off.

The property management company does the correct action, and sends out a plumber, in this case one who is experienced with the building, who turns on the valve that had been off. This new, experienced plumber charges $300 to turn on the valve.

Now, who pays that $300 bill?

Go ahead, answer in the comments.