I used to abide by the “in the walls” adage, but it may not be true. It depends on the language in your Occupancy Agreement (aka Proprietary Lease).

Before you get into arguments and/or pay any money, review your OA. You might not be responsible.

In my OA, it said the MEMBER (shareholder) is responsible for:

Replacement of electric refrigerator
Decoration and painting
Replacement of gas range/oven
Replacement of flooring linoleum
Replacement of all appliances and fixtures
Repair any and all damages to the apartment or co-op premises due to negligence, carelessness, or misuse by the shareholder or any occupants of the apartment.

It specifically states that the Corporation (the co-op) will for all other repairs besides the ones mentioned above.

In my co-op, the s/h would not be responsible for the cost of the faucet. It would be the co-op’s responsibility.

Check out the OA and keep your fingers crossed.

Good luck.

Ok that is really high. What is his hourly rate? It’s about $400.00? Your co-op needs a new plumber. Is this in NYC?

Thank you, Marty. Good idea, I will definitely read through the Proprietary Lease. But I know how the building manager is viewing this. One thing, however: I believe that faucets fall under "Replacement of all appliances and fixtures." I think a faucet is a fixture.
To be continued...

Yes, the coop is in Brooklyn. Unfortunately, the plumbing company is upstate. Thank you for your opinion.

A faucet getting clogged by debris from water shut-off is very common. It is a simple job and it is for the Superintendent to repair. If they elected to send a plumber for an out-of-the-wall repair like this then that was their mistake. Unless you asked for the plumber.... did you ask?
What is the full story and what is up with your super?
We have a corrupt one. It is terrible.
Who is your managing agent? They sound terrible.
We have Halstead. Not good.

God coops are the worst. And most managing agents.
It sounds like you have a misinformed board and a bad managing agent.
Firstly, I believe they legally have to give notice before turning off water.
Secondly, they should have sent the Super to restore the flow of water.
You do not say if your trap was clogged? Was it clogged?
But a trap below the sink doesn't have to do with the flow of water?
Thirdly, any well run coop should have alerted you you might be sent a bill before you say yes to the work.. And given the option to hire your own plumber. You did not retain these plumbers., the coop did.
No, it is not your bill to pay. Send a certified letter to mng agent and board president stating you are not responsible.

This issue is two folds: 1) Is the coop responsible if the sediments in the pipes reaches the faucets of the shareholders? Sediment in pipes is a normal occurrence so I would say that is not the Coop responsibility even if the sediment moved around because of a repair. 2) Is the coop responsible for the plumber's bill? From your description it sounds like you asked for a plumber and a plumber was sent to your unit. The Super could have handled this better but if you ask for a plumber and the job is not a coop issue, the bill is on you. About the bill amount: Unfortunately Coops can only hire vendors who carry adequate (very high coverage) insurance policies and the cost is passed back to the client. $400 for a house call is average in NYC these days. Next time ask the super to do the work and hand him a $20 (Yes, he should be paid because when he does something that is the shareholder's responsibility, the super is working for you, not the Coop.).