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Molybdenum and its applications

 

Preserving Water Resources with Stainless Steel

Water is a precious resource. Many parts of the world are facing water use limitations due to drought, polluted ground water, or deteriorating water tanks, mains and lines that cause the loss or contamination of potable water.  Water is critical to human health, agriculture, industry and safety (i.e. fire fighting).

Stainless steels have been used in the treatment, storage and distribution of drinking water for over forty-five years.  While stainless steel plays an important role in water treatment plants and desalination, this article will focus specifically on water conservation, distribution and building applications and the contribution of stainless steel to the sustainability and resiliency of these systems. The resource section at the end of this article provides papers, articles and brochures for further reading.

Building Applications

Stainless steel is increasingly being used for small on-site water storage, treatment or filtration units. These small units clean building waste and gray water, so that potable water consumption is reduced. They are ideally combined with stainless steel roofs and drainage systems, which unlike many other roofing materials, have metal run-off levels well below drinking water limits, making them an ideal solution for potable, irrigation or gray water applications. Capturing and using rainwater minimizes the structure’s overall environmental impact.

The Pittsburgh Convention Center, completed in 1981, is an excellent example of how much water can be saved over time through the use of gray water and on-site wastewater reclamation. Photo credit ATI Allegheny Ludlum

Water Storage & Transportation

Stainless steel is increasingly being used to store and transport potable water to minimize loss to the environment because it combines excellent seismic and corrosion performance. Extensive comparative global research on metal corrosion using a wide range of soils and water types has consistently demonstrated the superior performance of stainless steel, even in aggressive, high-chloride content soils. However, it is critical to select an appropriate alloy for the environmental and water conditions based on expert guidance.

Water Tanks
When a water storage system is breached due to a screen failure, steel tank corrosion perforation, a knot hole in a wooden tank, or deteriorating concrete, the effect on human health can be significant. These problems can be avoided by using tanks made from appropriate stainless steel alloys. Additionally, relining deteriorating concrete water tanks with stainless steel has been found to be a cost-effective solution for preventing water loss.

The US Environmental Protection Agency presentation Finished Drinking Water Storage Tanks documents the rodents, snakes, bugs, and other common sources of contamination found as the result of water storage tank breaches and the serious health risks caused by them.

In seismically active parts of Asia, stainless steel water tanks are widely used in conjunction with stainless steel distribution and building water lines because of their excellent combination of corrosion and seismic performance.
Photo credit Japanese Stainless Steel Association

Water Mains
Leakage of drinking water is a major challenge in all parts of the world. The Organisation for Economic Co-operation and Development (OECD) concluded that water loss in major cities can exceed 40%. Loss of treated, potable water into the environment from leaking pipes is an expensive and unsustainable waste of one of the world’s most important natural resources.

Additionally, the contamination of water from both pipe corrosion and infiltration of toxins and bacteria from the surrounding soil presents both environmental and human health concerns. To solve these problems. stainless steel water lines and liners for existing crumbling concrete pipes have been used in Asia and Europe.

Water Main Connecting Lines
The water lines connecting water mains to individual buildings are called service water lines and were historically made from lead and other materials that can leach compounds and are deteriorating over time, resulting in both significant water loss and public health concerns. In fact, 95 % of all leak repairs are typically in these small diameter pipes and, because the leaks are relatively slow, they can go unnoticed for years.

In Japan, Taiwan and Korea, there has been widespread replacement of these lines with partially corrugated stainless steel tubing. Stainless steel pipes have helped to significantly decrease water losses. Pipes made of stainless steel have a higher strength to weight ratio, are easier to work with, are resistant to corrosion and are strong enough to withstand shocks from seismic activities.

The partially corrugated pipes also can be bent as needed, largely avoiding leak-prone connections.  In Tokyo, the authorities replaced the existing service line infrastructure with Type 316 stainless steel pipe and made other improvements to the system. As a result, the water losses between 1980 and 2013 were reduced from 15.4% to 2.2%. The volume of the leaked drinking water was reduced from 260 million cubic meters to 33 million cubic meters per year.  Other cities, including Taipei and Seoul, have seen similar results.

Images from A Workable, Lasting Solution for Water Losses through Leaking Water Pipes (ISSF).
This brochure on water line connections between main line pipes and buildings and is also available in Chinese, Dutch, French, Italian, Korean, Portuguese and Spanish.

Resources

Buildings

Corrosion Performance in Soil

Water Lines & Tanks