Previously published in Plastics Engineering and posted with permission from the Society of Plastics Engineers.
This is the second of two articles on plastic pipe. The first article focused on HDPE pipe.
The previous article from Plastics Make it Possible in this publication reviewed the problem of water loss in the U.S., noting that the pipes that deliver fresh drinking water and carry away wastewater in many towns and cities are old and leaking, wasting precious water and financial resources.
A Ticking Clock
How big is this water infrastructure problem? If you want a startling visual of the problem, check out watermainbreakclock.com, a site that continuously updates the damage from broken water mains.
According to the site run by Uni-Bell PVC Pipe Association:
- Each day, an average of 850 water main breaks occurs in North America.
- Since January 2000, there have been more than 5 million broken water mains in North America that resulted in more than $50,000,000,000 in water main repair costs.
- Fifty percent of all water network operation and maintenance costs – and ninety percent of lost water costs – are corrosion-related. According to a 2002 congressional study, corrosion costs U.S. water and waste water systems more than $50.7 billion annually. Since January 2000, the price tag for total corrosion costs in these systems is more than $660,000,000,000.
Decades-old lead, cast iron, steel, and cement pipes remain prevalent. Corrosion, leaks, and breaks in these traditional pipe materials are degrading drinking water and wastewater systems. Trillions of gallons of potable water are lost every year through leaking pipes – water that went through expensive treatment.
Replacing the old pipes is a hugely expensive affair, but it’s not only a financial problem. Water delivery and sewage treatment are critical to the environment and public health. For example, a form of internal corrosion and bio-film contamination called tuberculation can develop in iron pipes and restrict water flow, which can create a breeding ground for bacteria. It can also increase the amount of pumping energy needed to move water through the system. In 2000, E-coli infiltrated the iron-pipe water network in the town of Walkerton, Ontario. Only after repeated and costly flushing with super-chlorination was the system deemed safe to use again.
Plastic Pipe Rising
Communities that are grappling with these problems can choose to repair old pipes, replace them, or a combination of both. And more and more, communities are realizing that modern plastic pipe can be a huge part of the solution.
There are several different types of plastic pipe, and the focus of this article is PVC pipe that is commonly used in water and sewer pipes. PVC pipe was introduced into the U.S. sewer, water, and drainage market in the 1950s. It is now recognized by state, national, and international agencies and standards organizations as an extremely durable alternative to traditional corrosion-prone pipe materials. PVC’s advantages include:
- It is corrosion resistant and can last in excess of 100 years, requiring less frequent replacement;
- Its smooth surface means that less energy is needed to pump water through it;
- Less energy is required to manufacture PVC than traditional pipe materials;
- Its lighter weight makes it easier and less costly to handle, transport, and install;
- It pipe can help save money over the life cycle of a pipe network since increasing amounts of energy are required to operate corrosion-prone piping systems as they deteriorate; and
- PVC is recyclable – however, since it is so durable, most of it has yet to enter the recycling stream.
Given these advances, it’s no wonder that Engineering News-Record, a publication for construction industry professionals, in 1999 recognized PVC water and sewer pipe as one of the top 20 engineering advancements of the last 125 years.
One other major benefit of PVC pipe is its ability to be installed without creating massive trenches that can severely disrupt roads, pedestrians and communities.
Traditional water pipes usually are laid in sections in a series in large trenches and then joined from above ground to form long pipes. By contrast, it’s sometimes possible to use trenchless construction for plastic pipe. This typically involves small, localized excavations – the pipe is installed by either pulling or pushing it through pre-drilled bore holes. It’s also possible to rehabilitate pipelines without digging up the entire line by inserting the PVC pipe through deteriorating old lines. This process often can restore the structural integrity of the pipe faster, with less expense and without digging it up.
Today, more than two million miles of PVC pipe are in service throughout North America, and tens of thousands of North American water utilities rely on it. Indeed new drinking water distribution pipe is a growth market for PVC.
However, one impediment to further inroads into water markets is procurement practices that favor older, traditional materials, as well as non-competitive bidding. The plastic pipe industry and numerous public officials have been tackling this issue, urging communities to use open procurement processes that yield cost-effective public benefits – such as a stronger, longer lasting water infrastructure.
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