Straining hot pasta water over the sink can soften or even melt your sink's plastic pipes, which can typically withstand temperatures between 140 and 200 degrees Fahrenheit.
For pipe-safe water draining, you should first strain your cooked pasta, veggies, or rice by placing your colander over a container designed to withstand high temperatures.
Then, let the hot water cool off and dump it down the sink. Boiling water takes about 12 minutes to go below 140 degrees Fahrenheit and about 45 minutes to get to room temperature.