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 man-power 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 having your work either be destroyed or develop a certain issue as a result of a certain factor you didn’t consider ?. As plumbers, it’s very underwhelming. However, this article will emphasize on the factors to consider when choosing a pipe for your out-door plumbing jobs either you’re a plumber or the one employing the plumber.

NOTE; This article will not emphasize on “pipes for outdoor underground plumbing”, to read that. Click HERE

When considering pipe materials to be used, a list of quality and reliable materials come to mind but being mindful of various factors, both general and for specific requirements, Stainless steel stands out as a strong favorite to be used. It is resilient enough against mechanical and chemical stress, is immune to ultra violet rays and although it comes across as expensive, it is corrosion resistant, good for portable 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, they are aesthetically profound, brass pipes even though they are old school comes 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 need be include;

  • Vitrified clay pipes
  • Asbestos pipes
  • Concrete pipes


Resistance to ultra-violet radiation;

Best; Steel pipes, preferably stainless steel

 Most steels are conventionally immune to ultra violet radiation (rays from the sun). The radiation takes effect by affecting the molecular structure of materials as the light penetrates into them causing the molecular chains to break up and their bonds to weaken over time with constant exposure(More or less like a relationship). This effect suffices when the materials turns 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, they 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.

Resistance to strong climatic changes (high temperature and low temperature);

Best; Stainless steel

This is a very peculiar factor as it relates to every region of the world. There comes a time where 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 either melt, expand or warp due to heat or they break as result of the cold.


Steel and iron can however resist both extremes beyond its 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 a 1000 degree Celsius and as low as -100 to -270 degrees Celsius. So finding the right grade and using it for domestic reasons is advisable as they provide assurance against any detriment by temperature.

Resistance to high impact by mechanical stress;

Best; Cast iron

According to their basic property of being resolutely strong, cast iron can resist a substantial amount of external impact without damaging. They are very brittle and contain richly a vast amount of material since they are relatively thick. When comparing to plastic, concrete and steel, even clay, with regards to mechanical impact. Cast iron has incomparable searing power as it possess a lot of thermal energy, it does not `warp but flat and true. Cast iron stands out as the best, certain grades of steel can match the strength of cast iron, but such grades would be excessive and too expensive for domestic use.


Going into a little more detail; cast iron contain 2 to 4% of 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 amongst others. Carbon and silicon are the main components that affect the micro-structure, strength and properties of cast iron.

Resistance from chemical stress;

Best; 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 whilst to plastic, 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 majorly iron which tends to rust over time even with protective coatings. Galvanized steel is also majorly steel with slim zinc coatings to prevent corrosion. Either in chemical-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 alongside iron, nickel, manganese and copper. Chromium is a rare metallic property that forms a very slim layer of chromium oxide on the surface of 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.

Safety for water consumption;

Best; 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 my health or which is least likely to have me 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 portable water. Although over a period of time, it has been increasingly criticized of releasing copper ions in water which is dangerous to the human health. Plastic pipes have also threatened behaviors of similar pattern 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 researches are also being made on its regards but so far it has shown adequate corrosive resistance and impermeability showcasing its ability to convey and maintain portable water without contamination.

Aesthetic impact;

Best; 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 on its own accord. However, the supplicated look is adds to any construct makes it very unique, a feat only stainless steel can near with outdoor works.


Brasses have ranges of attractive colours and with 1% manganese 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.

Longevity; 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 the longevity not for the sustainability of materials. A reason why recently, they have been mostly used to channel sewage or foul water. Its clear likeliness to corrode and contaminate contained fluid denounces it as an option for portable water. Looking for the materials with the right balance of longevity and suitability is best.

water tank




Best; Plastic pipes

The basic costs of each pipe and their cost of installation vary due to the availability of raw materials, its functionality, quality and resale value. Plastic pipes are the cheapest but are not ideal for outdoor use if you understand that its degrades on exposure to sunlight, might possibly break when exposed to low temperatures, its likeliness to get damage due to its limited strength and possible effect on contained water; although if all these can be ignored and you wish to take the risk, getting pvc pipes are the most favorable. On the other, stainless steel pipes are the most expensive and offer the most in terms of functionality, safety and value.