Holding Workers Responsible for Pipe Blockage?

[Teddy Mao]

Moved out of my condo in early January and start to turn it into a rental property. My first project was replacing the vanity countertops and sinks in my bathrooms. When my workers ran the water for testing after they finished, my downstairs neighbor observed an overflow in her kitchen sinks.

Later HOA asked plumbers came to fix the pipes. They claimed there are 3 feet of sandy stuff blocking it and they have to auger it through. HOA then encourages me to hold my workers responsible. Their reasoning is based on the following:

1.The overflow happened right after my project. Everything was fine before then.

2.The amount and density of the sandy stuff is likely a result of introducing grouts or other construction garbage down the drain, instead of day-to-day usage.

3.The location of the clog is only connected to my kitchen and my neighbor's kitchen.

However, I could see some potential points of failure in this logic. I cannot even convince myself charging this against the workers. Questions like:

4.The workers only worked with bathrooms, which are on a different floor from the kitchen.

5.Grout is not supposed to be used in a vanity countertop installation. Glue is used for attaching things. There are also no signs of tile works. The workers have even come earlier to measure the dimensions to avoid cutting materials and introducing dust at my property.

6.The test water run was the first time in the past 3 weeks that someone has run water constantly in my unit. The blockage could have already been there but just not triggered.

This is the first time I remotely manage a property and it is really a big headache for me. Checking with the workers isn't really helpful, as they won't say they dumped things, whether they did it or not.

My questions:

1.Any suggestions on how to avoid such controversial things when managing remotely? I have an agent but she just cannot stay there for hours supervising the workers.

2.I probably won't do this, but if we were to go to the small claim court, which side is more favorable given the evidence so far?