The supply and drainage subsystems are two different operations, with nothing between them. There are bridges between the two the create the plumbing to work. In plumbing jargon, another bridge between the distribution and drainage systems is an element.
Toilets, sinks, and bathtubs are fixtures. Additionally, an outside faucet is a fixture and a washing machine. All devices that draw freshwater and release wastewater are appliances. All are intended to maintain the supply and drainage systems segregated. Some fixtures have distribution shutoff valves so you do not need to close the primary shutoff to repair them.
It is good idea to make sure everybody in the family knows the location of the shutoff valve in your home. Before you go on any plumbing repairs, always turn off the water source to the fixture or the shutoff. Also, check with the local plumbing code before you add or change any pipe in your house. You may learn what’s allowed and what’s prohibited an owner is allowed to do their own work. If you get the green light, you can save yourself a good deal of cash by doing your very own repairs.
If not, you can always give us a call.