ABS (Acrylonitrile Butadiene Styrene) and PVC (Polyvinyl Chloride) are 2 of the most popular plumbing pipes. Although both are plastic, there are some distinct differences that make each better for certain tasks than the other.
So, what is the difference between ABS and PVC and which one should you use for your project?
The main difference between ABS and PVC pipes is that ABS contains bisphenol A (BPA) while PVC doesn’t. ABS pipes have a higher shock resistance and are better at handling extreme cold temperatures but will warp when exposed to sunlight. PVC pipes offer more flexibility and also muffle the sound of running water.
Sometimes the choice on what type of pipe to use is not in your hands. Some areas have regulations on what types of pipes to use so you should definitely check your local building codes or consult a licensed plumber prior to starting your project.
Related: Types of PVC pipes
What is the Difference Between ABS and PVC?
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While the differences are not many, it is important to know since they impact your project in one way or another.
Here are the differences between ABS and PVC pipes including some of requirements of the same by governments and professional bodies:
In some areas, the use of ABS pipes is prohibited. That means you will have to stick with PVC pipes or even metallic ones.
The reason ABS pipes are prohibited in some areas is because they have not proved to be as durable as previously thought, resulting in serious damages to homes as well as threat to people’s health and safety.
While not all of ABS pipes are bad, lack of standardization in the manufacture of these pipes have seen some manufacturers produces substandard pipes which are the ones that tend to fail.
To protect homeowners, California for instance requires that all ABS pipes sold in the state to meet the specifications laid out by the American Society for Testing and Materials (ASTM). The requirements have been also incorporated into the Uniform Plumbing Code (UPC)
In Part, the California health and safety code states as follows “ABS pipe that does not meet ASTM requirements might, within a period of a decade or less, crack and leak wastewater and sewage, resulting in structural damage, vermin infestation, and severe health hazards for residents or occupants of buildings in which defectively manufactured ABS pipe has failed”.
The main reason why ABS pipes fail is due to the use on nonvirgin reprocessed plastic resin in their production. One of the recommendations of the ASTM is that ABS pipes be made from virgin plastic resin.
If you specifically want to use ABS pipes for your project, it will therefore be important to find out how they have been made. Ask if they are made of virgin plastic resin and insist on seeing the documentation to that effect.
2. Bisphenol A (BPA) in ABS Pipes
The main difference between ABS and PVC pipes is also a controversial one. This is due to the inclusion of bisphenol A, commonly known as BPA in ABS to improve its qualities.
BPA is added to ABS to make it hard and therefore durable. Why then is this a controversy rather than a good thing?
There have been some concerns that BPA is potentially harm to human and animals. The interest on the matter is especially high since food and water containers also contains BPA and that is why it is easy to see some containers labeled as “BPA-free” these days.
In this case, the only logical thing to do is to check what the Food and Drug Administration (FDA) has to do on the matter. And I did just that.
FDA states that “BPA is safe at the current levels occurring in foods. Based on FDA’s ongoing safety review of scientific evidence, the available information continues to support the safety of BPA for the currently approved uses in food containers and packaging”.
Although the above quote refers to food and water containers, I would want to imagine that the same standard also applies to ABS pipes.
You will hardly choose a plumbing pipe based on its color but I reckoned it is important to mention. Most of the times, pipes are concealed behind a wall or laid underground so the color may not matter.
ABS pipes are usually black in color while PVC pipes are white.
This refers to the ability to bend the pipe without cracking/breaking. If you are looking to snake your pipes through curves or corners then PVC would be the clear choice for you.
The BPA added to ABS makes it rigid so it is more likely to break if forced to go through a sharp bend. PVC on the other hand will easily go through a bend without cracking which makes it a favorite choice for most indoor plumbing projects.
Whatever ABS loses in flexibility it gains in tensile strength. It has a higher resistance to shock/impact than PVC due to the BPA.
If tensile strength is important in your project than flexibility, ABS pipes will be a better choice than PVC. This is however not to say that PVC pipes have a lousy shock resistance. ABS pipes are just better.
6. Temperature Ratings
ABS pipes are less likely to freeze compared to PVC pipes. If your project is outdoors and especially underground, ABS pipes will be a logical choice.
The temperature range for PVC pipes is between 0 and 140 degrees Fahrenheit while that of ABS pipes is between -40 to 158 degrees Fahrenheit.
Unfortunately, ABS pipes will warp when exposed to sunlight. Unlike metals which expand and contract, one plastic is deformed the change is usually permanent.
So, how does temperature affect the pressure ratings of both of these pipes?
At 68 degrees Fahrenheit, PVC is rated up to 218 psi while ABS has a similar pressure rating at the same temperature. Both pipes will therefore handle water pressure the same way when exposed to similar temperature.
7. Noise Muffling
I am sure you know the unmistakable sound of water flowing through a pipe. The main reason PVC pipes are preferred for interior plumbing is due to their soundproofing properties. PVC pipes muffle the sound of water as it flows through the pipes.
Is I mentioned, ABS is quite solid and acts like metal (sound wise) while PVC is quite flexible and acts like rubber. This is why PVC is able to silence the water as it flows through it quite efficiently.
8. Installation Process
Another difference between ABS and PVC pipes is how they are installed. ABS has a one-step process for connecting the pipes while PVC pipes have a two-step installation process.
ABS pipes are connected instantly using special cement while PVC pipes must first be primed before being cemented together.
The primer (usually purple) is messy and you must wait for it to dry. This means more time is used to install PVC pipes as opposed to ABS which will increase the total cost of the project.
Most plumbing codes restrict connections between ABS and PVC. Only use similar pipes for your entire project. Either stick with ABS or PVC.
If you area plumbing codes do not restrict the connections between PVC and ABC, you are better off using special fittings instead of glue. You can also use a rubber sleeve and a metal jacket to clamp the connection.
In conclusion, plastic pipes are proving to be better that metallic ones in the long run. If you house uses old galvanized steel pipes, check out here why I recommend replacing them with PEX.