Water Pipes for Plumbing

Published by: Nick Meissner

Using the correct pipe for a particular job can be quite critical. It is important to ensure that it is large enough to not restrict the flow of water, but yet not any larger than it needs to be (due to cost). There are also the considerations of what type of pipe to use and what strength rating. Many times there are at least a couple of good options. Before we give some recommendations, let's go over a few rules:

  • Whenever the pump manufacturer recommends a certain type or size of pipe, use that.
  • In most cases, don't use a smaller pipe size than the dimensions of the outlet connector on the pump.
  • Always use pipe that is strength rated higher than you ever anticipate needing.
  • The longer the run of pipe, the more friction is built up, and the more likely you will need to step up to a larger pipe.
  • The fewer the joints in your pipe, the fewer possible leaks and blowouts there will be (especially important for pipe that will be buried).
  • Avoid using 90 degree or 45 degree "elbows" as much as possible. These add more constriction and friction to your pipe line. That means less flow and more work for your pump.
  • When using a valve on your pipe, anytime having the maximum water flow is critical, be sure to use "gate valves" rather than "ball valves." While ball valves are easier and faster, they constrict the water volume more than one would think. This rule would especially apply to the intake line for a hydro unit or a ram pump.

Size of Pipe

This is an extremely variable topic. If at all possible, get advice from the company you bought the pump from or some one who is knowledgeable. Explain your system to them and see what they say. But as a general rule, as we stated above, use a size of pipe that is at least as large as the output on your pump. If the output on your ram pump is set up for a ¾ inch pipe, use at least a ¾ inch pipe.

Then there is the factor of length. As stated above in rule #4, the longer a pipeline is, the larger its diameter will need to be. Consult a plumber's handbook (usually available from Home Depot, Lowe's, Sears, local plumbing supply houses, etc.) or a knowledgeable professional for the exact size of pipe your system will require. For a hydroelectric unit, consult with the distributor for pipe dimensions. Pipe sizes come in quarter-inch fractions (1 inch, 1 ¼ inch, 1 ½ inch, etc.).

Type of Pipe

Traditionally, galvanized steel pipe was the most popular choice for residential water lines. But the advent of plastic pipes has dramatically changed that. Let's take a look at the different types of pipe and see what works where.


Polyethylene pipe is the workhorse of many of our water system needs. It has the advantages of being flexible, inexpensive, rustproof, and it comes in 100 foot lengths (sometimes 500 feet). All this makes it ideal for the long underground supply lines that take water from our spring or creek to the cistern.

One downfall of "poly" pipe is that is does not have the strength of some other types of pipe. So, while poly pipe is ideal for long underground runs in fairly low pressure settings, it would not be the pipe of choice for connecting a well to a household diaphragm tank (although poly pipe with an adequate strength rating, could work). It is ideal for delivering water to your cistern from a ram pump, gasoline powered water pump, springhead, etc. Whenever installing "push-on" fittings on poly pipe, be sure to heat (but not melt) the area of pipe where the fitting will be installed to ensure a good, water tight seal once the fitting is clamped.


PVC pipe that is "schedule 40" (strength rating) has the advantage of being rustproof and easy to handle along with the strength to handle pressure applications. It comes rigid in 10 and 20 foot lengths which makes it a possibility for use with a well pump or a handpump in a well. However, for very deep wells, PVC may or may not be recommended. It is important to have a VERY strong pipe when it is holding a pump 700 feet down in the ground. You do not want a pipe breaking there!

CPVC is not the same as PVC. While PVC is made for cold water pressure lines, CPVC can also handle hot water. Because of this, CPVC is more desirable than PVC for interior applications. While not as durable as copper interior pipes, it is easier to work with. And if your water is acidic, CPVC will not corrode like copper. There are some concerns, though, as to the health risks associated with using plastic water pipes.


In residential construction, copper pipe is generally only used for interior applications. It is more difficult to work with and expensive, but it is one of the longest lasting pipes that can be used in your house. However, copper is not recommended for use with water that is highly acidic. It could corrode. Use your own discretion.

Galvanized Steel

Galvanized steel pipe excels in uses such as a deep well and the drive pipe for a ram pump. It is very strong, not terribly expensive, and somewhat rust resistant. We do not recommend it for underground use (other than wells), though. It is generally accepted that plastic pipe is a much better route to go for residential underground use.


Pex is becoming increasingly popular due to its ease of installation (is flexible) and ability to withstand expansion from frozen pipes better than most pipe materials.

Stainless Steel

Usually cost prohibitive, the one application that stainless steel would be recommended for is connecting a thermosiphon hot water system to your wood cook stove.  Any plastic pipe (PVC, CPVC, Pex, etc) is not suitable for dealing with the level of heat produced with this type of hot water system.  Even with copper pipe, the temperature of pipes close to the stove can become incredibly hot if the stove is operated without water in the pipes (i.e. warming the cabin up before turning water on when returning home in the winter).

In that kind of scenario, the solder in the joints on copper pipe could potentially melt, meaning they would need to be re-soldered. This leaves threaded metal pipe on our list of potentials.  Galvanized steel pipe can work for a temporary setup or if you are on a tight budget, but can rust with time.  This is why stainless steel is the preferred pipe material for connecting a thermosiphon hot water system to a wood cook stove as well as for the water coil inside the stove.  For more info, see:  Hot water for free--from the wood cook stove!.

1 Comment

  1. Mike

    Great post


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