How Does a Bathroom Sink Work?
A bathroom sink works by providing pipes that supply hot and cold water to the faucet fixture and draining the water through the waste water pipe. Sinks include separate hot and cold water pipes as well as a drainpipe that connects to your household's waste water line, which then empties into your septic system or the municipal waste water system.
Hot Water Pipes
The hot water pipe for your sink receives hot water from your hot water tank or tankless hot water heater. The hot water pipe is usually located to the left side of the plumbing. In order to get the hot water into the faucet, the hot water pipe is connected to a water supply hose, which then feeds into the left side of the faucet stem.
Cold Water Pipes
The cold water pipe for your sink receives cold water from the main water supply of your home. The cold water pipe is usually located to the right side of the plumbing. In order to get the cold water into the faucet, the cold water pipe is connected to a water supply hose, which then feeds into the right side of the faucet stem.
Bathroom sink drains have a feature called a p-trap that prevents gasses from emanating up through the pipe and into the air. When water drains from the basin through the drain opening and into the pipe, it feeds into the waste water pipes of your home, which are separate from the water supply line. If your home is connected to a municipal water supply, you will have one main waste water line that delivers wastewater to the sewer system. If your home is on septic, the wastewater from the sink will drain into the septic pipe.