The three valves commonly found under a kitchen sink are typically for the hot water supply, cold water supply, and the main water shut-off. Here's a breakdown of each valve:
Hot water supply valve: This valve controls the flow of hot water to the faucet. It is usually connected to the hot water pipe coming from the water heater. By turning this valve clockwise, you can shut off the hot water supply to the sink, which is useful for repairs or when you need to cut off the hot water flow for any reason.
Cold water supply valve: This valve controls the flow of cold water to the faucet. It is connected to the cold water pipe and is responsible for supplying cold water for regular use. Similar to the hot water supply valve, turning this valve clockwise shuts off the cold water supply to the sink.
Main water shut-off valve: This valve controls the entire water supply to the kitchen (and often the entire house). It is usually located where the main water line enters the house or near the water meter. The main shut-off valve allows you to completely stop the flow of water to the kitchen (and the rest of the house) in case of emergencies, such as a burst pipe or plumbing repairs. It's important to know the location of the main shut-off valve in case you need to quickly turn off the water supply.
These three valves provide control and convenience when it comes to managing the water supply to your kitchen sink. They allow you to isolate the hot and cold water independently and to shut off the water completely if needed. This can be useful for repairs, maintenance, or emergencies, and it helps in minimizing water wastage and potential damage in case of plumbing issues.