What is the difference between water pipe and sewage (waste) pipe?

Wednesday, July 4, 2018

All plumbing pipe must be tested before being certified/rated for its intended use by the National Sanitation Foundation (NSF) and accepted by the building codes. Pipe that is rated for potable water must be designed to be used under pressure and not leach any contaminants from the pipe material into the water. Sewage pipe, also called DWV for “Drain Waste Vent,” does not have to meet those standards, but must be structurally stable and suitable for the disposal of water or wastewater.

    Pipe that has been approved and rated for potable water will be marked with “NSF-PW” or “NSF-61” in the line of printed data along the side and, obviously, only rated pipe should be installed. Because different PVC pipe can be used for water service pipe to a home (but not inside) or drainage pipe, the PVC pipe rated only for drainage will be marked “NSF-DWV,” which stands for Drain Waste Vent. 

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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? 

Is it alright to have a shut-off valve on both the hot and cold water pipes at a water heater?

Why can't a sanitary tee be used for a horizontal-to-horizontal drain pipe connection? 

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?  

Why is it a problem when a trap under a sink is installed backwards? 

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? 

How can I tell the difference between Corrugated Stainless Steel Tubing (CSST) and a Flexible Appliance Connector (FAC)?

What is a "combination waste and vent" in a plumbing system? 

Does a "QEST" brand mark on pipe mean that it is polbutylene (PB)?

What is a building trap?  

What is a galvanized nipple?

What are the pipes sticking out near my water valves?

Can PEX pipe be installed outside?  

 Is PEX pipe freeze resistant?

How do you accurately find a broken water pipe leak under the floor slab?

Are plastic pipes (PVC, CPVC, and PEX) safe for drinking water? 

What do the ABS, PVC, CPVC, PB, and PEX plumbing pipe names mean?

Is a hot water faucet handle required to be on the left? 

Why is sunlight exposure bad for PVC pipe?

Why can't PVC be used for water pipe inside a house?

What is a dielectric union? 

What's that powdery crust on the pipe connections at the water heater? 

Can I make a trap under the sink from straight pipe and 90º elbows?  

What type of white plastic pipe has the marking CP-112-P in red letters? 

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? 

What is an "S-Trap" under my sink? Why is it a problem? 

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?

• Should I buy a house with galvanized steel water pipes?

• 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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