Water pressure is controlled by the internal diameter of the pipes. The smaller the diameter, the lower the water pressure, and the greater the velocity of water moving through it. 

In order to ensure proper function, there is a standaardized system of building codes that control many aspects of plumbing including:  

• Internal pipe diameter that must be used for a particular function
• Amount of slope or downward drop that drain pipes need to function properly

Water Supply

In most homes, water comes from one of two places; a private well (not so common in our area), or a service pipe that connects to the city's water main.

For homes with private wells, a pump pushes water up into a pressure tank where it is stored for use. Homes with city water have a water supply line that is connected to the city's water main. Water passes through a water meter that measures the volume of water used in the house. In case of repairs or emergency, both systems usually have a shut-off valve located near the start of the incoming line that enables the water supply to be temporarily cut off.

Water supply lines are generally made of copper, chlorinated polyvinyl chloride plastic, (CPVC), or galvanized steel. Pipes that carry cold water branch out from the main pipe. Some water is directed to the hot water heater for heating, and hot water pipes originate from there.

Where Does Wastewater Go?  

When wastewater goes down the drain, it forst passes through a trap; a U-shaped curve in the pipe that retains a small amount of water so that sewer gas cannot come up through the pipes and enter your home. It then passes into the main waste drain pipes.

The main component of the waste drain is the soil stack, a vertical stack of pipes taht is connected to the outbound sewer line. The stack has a vent which extends vertically through the roof, allowing gases to escape and promote drain flow by drawing air inward. It's very important to keep this vent clear. Plugged vents can trap dangerous gases and inhibit drainage.