How To Look At A House

McGarry and Madsen's home inspection blog for buyers of  

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What is the difference between water service pipe and water supply pipe?

Thursday, September 20, 2018

Water service pipe connects at the house side of the water meter and runs across the yard to a point near where the water enters the home. There is sometimes a shut-off valve at this point, and the piping that runs inside the home distributing water to the plumbing fixtures is called water supply pipe. Another name for water pipes inside the home is water distribution pipe—which is the name used in the International Residential Code. Here is how the two are defined in the IRC:

Water Service Pipe - The pipe from the water main or other source of potable water supply, or from the meter when the meter is at the public right of way, to the water distribution system of the building served.

Water Distribution Pipe - A pipe within the structure or on the premises that conveys water from the water service pipe, or from the meter when the meter is a the structure, to the point of utilization.

  The pipes that drain the sinks, tubs and toilets are the wastewater piping. Unlike supply piping, it is not pressurized, and requires vents that admit air to the system in order to drain properly.

   There are two types of water supply pipes have proved to be problematic over the years: galvanized steel and polybutylene. Polybutylene is no longer code-approved due to premature failure of the material, and galvanized steel is not used for new installations due to corrosion buildup. 

    Also, see our blog posts Are plastic pipes (PVC, CPVC, and PEX) safe for drinking water? and What do the ABS, PVC, CPVC, PB, and PEX plumbing pipe names mean?

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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?  

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.

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