Pipe Basics to Know Before Re-Piping or Drain Repairs

Pipe Sizing

Water supply pipes do not have to be very wide, since the water supply is pressurized anyway. Drainpipe tends to be larger in diameter. Since water is not pressurized in your drain lines, and drains often have to allow a lot of water to flow through at once (such as when you drain the tub after a bath), this wider diameter is necessary.

Different drains and freshwater pipes in different locations may have different diameters as well. Some of the typical diameters for parts of the plumbing system include the following:

• Kitchen or bathroom sink drains typically use 1 1/2 inch pipe
• The main water line into your house typically uses 1/2 to 3/4 inch pipe
• The freshwater line that leads to a plumbing fixture or appliance often uses 3/8 to 1/2 inch pipe
• Main drain lines (that all your smaller drains empty into) generally use 4-inch pipe
• Toilet drain lines typically use 3-inch pipe

However, these sizes are not necessarily set in stone. You can sometimes choose a slightly different pipe size than the standard one. For instance, with a larger house, you may want a wider pipe size for your main drain. Or if you are tired of unclogging your kitchen sink drain, you can choose a slightly larger sink drainpipe size.

Pipe Materials

The materials for plumbing pipes can also vary based on their application. Drain lines are generally of cast iron, PVC, or chromed brass, for instance. Chromed brass is often the choice for drain lines that need to look attractive, while the other two are more utilitarian.



When you need to re-pipe your home, you can typically choose between several pipe materials for your freshwater lines as well. These supply lines often use PEX, CPVC, or copper piping. The best option for your re-piping job may depend partially on your budget (copper pipe can be expensive, for example). 

Pipe Connections

Different pipe materials require different types of connections. For example, PVC pipe connections use a type of solvent that cements the two pieces of pipe together in a process called solvent welding. Copper pipe can be soldered together or connected with specialized push-to-connect fittings.

Connections get more complicated if you have different types of pipes in your home that need to be joined together. Connecting dissimilar types of piping typically requires some type of adaptor. Welding may also be necessary, as well as specialized tools to install the adaptor.

These are some of the basics about pipes for the water supply and drainage components of your plumbing system. Your plumber can help you navigate the task of choosing the best pipe materials for re-piping your plumbing system and answer any questions you have about pipe diameter, plumbing vents, or pipe insulation.

Get in touch with Art Douglas Plumbing Inc. today to learn more about the services we can provide. We offer not only re-piping services but also drain cleaning, in addition to maintenance and repairs for drains and any other aspects of your plumbing system. We look forward to helping you with all your plumbing needs. Please let us know what questions or concerns you may have as well.