coffee water from tap

Yesterday when I reached home, I turned on the water tap and what came out was coffee (colour) water! You will think I should get high since it's coffee, but no it wasn't coffee, but some yucky mixture with dunno rust or mud smell. I didn't test its taste though.

What happened was, the town council had just changed the water pipes and mains in our block (and filled the water tanks with coffee).

I'm not into fluid mechanics but let me try. In a real pipe flow, the velocity at the wall is zero, thus all the sediments got deposited there and stayed there. When they changed the pipes, they had to switch off the supply and let out the remaining water inside the pipes. Air took over the volume. Then when they turned on the supply again, the water came rushing into the empty pipes under pressure and push all the crap inside the pipes.

My toilet's water tank was filled with "coffee".

So next time after they have changed your pipes, let the water run for a while before using.