The water pressure serving a house is the same at all sizes of pipe because it is a static measurement, meaning that it is determined with no water flowing. But, as soon as a faucet is opened, the pressure will drop and smaller pipes have a larger pressure drop, with the consequent slow-down of flow. Larger pipes offer less resistance to water flow, so there will be less pressure drop and more flow.
Longer pipe runs also decrease pressure/flow, so a combination of both small pipe diameter and long pipe run can cause a dramatic pressure drop. One example would be when multiple faucets in the same bathroom at the far end of a house that are opened at the same time. The friction from corrosion on the interior surface of old galvanized steel pipe will also reduce pressure/flow. To learn more, go to our blog posts What causes low water pressure in a house? and Does a home inspector check water pressure?
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Here’s links to a collection of our other blog posts about PLUMBING PIPES:
• How can I protect my pipes to keep them from bursting during a hard winter freeze in North Florida?
• Can galvanized steel pipe still be used for new water lines in a house?
• How can I tell if I have cast iron pipes in my house?
• Why can't a sanitary tee be used for a horizontal-to-horizontal drain pipe connection?
• What is the difference between green and white sewer drain pipes?
• Is a washing machine drain hose required to be secured at the standpipe?
• What are the abandoned pipes sticking out of the wall in my house?
• What are the code requirements for plumbing vent terminations?
• What are the code requirements for layout of drain piping under sinks?
• What causes a gurgling sound when a bathtub or sink drains?
• What is a "combination waste and vent" in a plumbing system?
• What is a building trap?
• What is a galvanized nipple?
• What are the pipes sticking out near my water valves?
• How do you accurately find a broken water pipe leak under the floor slab?
• What is the difference between water pipe and sewage (waste) pipe?
• Are plastic pipes (PVC, CPVC, and PEX) safe for drinking water?
• Is a hot water faucet handle required to be on the left?
• What is a dielectric union?
• What's that powdery crust on the pipe connections at the water heater?
• If all the plumbing drains have water in them and you can still smell sewer gas, what's causing the problem?
• How can I tell what type of plumbing pipe I have?
• Why is there a flexible accordion pipe under the sink?
• What is the difference between PVC and ABS plumbing pipe?
• What is the difference between water service pipe and water supply pipe?
• What are the pipes on my roof?
• How can I find out what type of water pipe runs underground from the water meter to the house (service pipe)?
• What is a P-trap?
• Why is old galvanized steel water pipe a problem for homebuyers?
• What does polybutylene pipe look like? Why is it a problem?
• Which water pipes are an insurance problem and possibly uninsurable?
• Can you connect CPVC pipe directly to a gas water heater?
Visit our PLUMBING page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.