Best Outdoor Water Pipe Material


Being a plumber, having to work outdoors beyond the walls of a structure is one of the tough aspects of the profession.

Figuring out the best material required for each situation of the job, the environmental factors to affect your work, and implementing adequate manpower to achieve your goals.

Sounds like a simple and direct procedure; don’t you think?

But going through all that process, getting the job done, and then having your work either be destroyed or develop a certain issue as a result of a certain factor you didn’t consider – as plumbers, these are very overwhelming.

However, this article will emphasize on the factors to consider when choosing a pipe for your outdoor plumbing jobs whether you’re a plumber or the one employing the plumber.

When considering pipe materials to be used, a list of quality and reliable materials comes to mind, but being mindful of various factors, both general and for specific requirements.

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Stainless steel stands out as a strong favorite to be used. It is resilient enough against mechanical and chemical stress and is immune to ultraviolet rays. Although it comes across as expensive, it is corrosion-resistant, good for potable water, and most of all, provides a good value for money over a long period of time.

We here value stainless steel, as not only do they seem perfect for outdoor constructs, but they are also aesthetically profound; brass pipes, even though they are old school, come as a close one too.

However, here are the lists of piping materials that can be utilized for the outdoors and the factors to be considered when choosing a pipe for outdoor construction.

  • Galvanized steel pipes
  • Brass pipes
  • Stainless steel pipes
  • Cast iron pipes
  • Plastic pipes (PVC, CPVC, HDPE, etc.)
  • Copper

Other materials that can be utilized if needed include:

  • Vitrified clay pipes
  • Asbestos pipes
  • Concrete pipes

8 Important Factors To Consider When Choosing A Pipe For Outdoor Plumbing

We included the best pipe to pick to counter each of the listed factors.

1. Resistance to Ultraviolet Radiation

Best pipe: Steel pipes, preferably stainless steel

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Most steels are conventionally immune to ultraviolet radiation (rays from the sun).

The radiation takes effect by affecting the molecular structure of materials. That’s as the light penetrates into them causing the molecular chains to break up and their bonds to weaken over time with constant exposure.

This effect suffices when the materials turn into dust. For this reason, plastic pipes such as PVC or CPVC even PEX cannot thrive outdoors when exposed to the sun the same way metallic alloys can, considering this factor.


Metallic alloys, apart from being extremely dense/tough in nature, are put through processes such as carbonization (one amongst the rest), which allows iron or steel to absorb carbon while the metal is being heated. This further increases its strength and impermeability to air, light, or moisture.

Stainless steel, however, possesses the best of this trait.

2. Resistance to Strong Climactic Changes (e.g. High and Low Temperature)

Best pipe: Stainless steel

This is a very peculiar factor as it relates to every region of the world.

There comes a time when the temperature of the land either becomes too hot or freezing cold. It’s a common feature of the outdoors and it has to be considered.

Plastic pipes don’t react well to both extremes because they melt, expand or warp due to heat, or they break as a result of the cold.


Steel and iron can however resist both extremes beyond their domestic requirement; they can also be utilized for harsh chemicals and be put under extreme heat.

Notably, steel can resist temperatures from ambient to as high as 1000 degrees Celsius and as low as -100 to -270 degrees Celsius.

Finding the right grade and using it for domestic reasons is advisable, as they provide assurance against any detriment by temperature.

3. Resistance to High Impact by Mechanical Stress

Best pipe: Cast iron

According to its basic property of being resolutely strong, cast iron can resist a substantial amount of external impact without damage. They are very brittle and contain richly a vast amount of material since they are relatively thick.

When compared to plastic, concrete, steel, and even clay, with regards to mechanical impact, cast iron has incomparable searing power as it possesses a lot of thermal energy. It does not warp but is flat.

Cast iron stands out as the best for this factor. Certain grades of steel can match the strength of cast iron, but such grades would be excessive and too expensive for domestic use.

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Going into a little more detail: cast iron contains 2% to 4% carbon content, 1% to 3% of silicon, as well as manganese, phosphorus, sulfur, and other elements.

Alloy cast iron also contains nickel, chromium, aluminum, copper, and vanadium, among others. Carbon and silicon are the main components that affect the microstructure, strength, and properties of cast iron.

4. Resistance from Chemical Stress

Best pipe: Brass, Stainless steel

Chronic degradation of materials happens as a result of constant exposure of pipes to environments with high acidic or chemical presence.

To metals, corrosion occurs. For plastics, they happen to crack, melt or weaken in strength.

Galvanized steel and cast irons have resistance against corrosiveness, but eventually give in, because cast iron is mostly iron that tends to rust over time even with protective coatings. Galvanized steel is also mostly steel with slim zinc coatings to prevent corrosion.

Either in a chemically mild environment or in one with high acidity, both metallic properties still corrode naturally over a period of time.


Brass and copper contain high levels of zinc, which draws a misconception that they do not corrode, but with constant exposure to an acidic environment, they tend to rust.

Stainless steel contains chromium, iron, nickel, manganese, and copper.

Chromium is a rare metallic property that forms a very slim layer of chromium oxide on the surface of the steel. Because it is non-porous, it prevents it from corrosive detriments.

Except when exposed to an extreme chemical – immense/acidic environment constantly, they do not corrode.

5. Safety for Water Consumption

Best pipe: Stainless steel

Considering if a pipe material is ideal for portable water, especially for domestic use, is paramount. 

With advantages each material may pose over one another, the decision of which one is best for one’s health, or which is least likely to have anyone dead by cancer, is the one most people go for. 

Unlike galvanized steel and cast iron, copper stands firm as it doesn’t degrade with water and resists the growth of bacteria, making it safe for potable water.

Although over a period of time, it has been increasingly criticized for releasing copper ions in water, which is dangerous to human health.

Plastic pipes have also threatened behaviors of similar patterns, releasing particles into contained water.


However, the use of stainless pipes is not overly common, except in certain parts of Europe.

Although its superiority in quality has suggested that it does outperform the rest, further research is also being made. So far, though, it has shown adequate corrosive resistance and impermeability, showcasing its ability to convey and maintain portable water without contamination.

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6. Aesthetic Impact

Best pipe: Brass

Quality service from a craftsman comes from his ability to create something beautiful, a sculpture from nothing but materials and tools.

Choosing the right pipe for your outdoors and ignoring other relevant factors, brass stands out as an aesthetically desirable material for plumbing. Other materials, if utilized properly, can create a unique look of their own accord.

However, the supplicated look adds to any construct and makes it very unique, a feat only stainless steel can near with outdoor works.


Brasses have a range of attractive colors. With 1% manganese, it will weather to chocolate brown, and nickel polishes will have them polished to silver.

Brasses are easy to shape to required mould. Architects, designers have used brass as they understand its conceptual beauty. Not so much for plumbers anyway.

7. Longevity

Best pipe: Cast iron

Most plumbing pipes last 30 years and above if properly treated and maintained. However, cast iron pipes can last up to 100 years, outliving other forms of mentioned pipes.

The properties of a cast iron pipe material are built for longevity, not for the sustainability of materials. It’s a reason why they have been mostly used to channel sewage or foul water.

However, cast iron’s clear likeliness to corrode and contaminate contained fluid denounces it as an option for potable water.

Looking for materials with the right balance of longevity and suitability is best.

water tank

8. Cost

Best pipe: Plastic pipes

The basic costs of each pipe and their cost of installation vary due to the availability of raw materials, their functionality, quality, and resale value.

Plastic pipes are the cheapest, but these are not ideal for outdoor use. That’s because they degrade when exposed to sunlight, might possibly break when exposed to low temperatures, and may get damaged due to their limited strength and the possible effect on contained water.

If all of these can be ignored and you wish to take the risk, getting PVC pipes are the most favorable.

On the other hand, stainless steel pipes are the most expensive, but offer the most in terms of functionality, safety, and value.