A plentiful supply of clean potable water is surely an essential component of a healthy living environment. However increasing living standards and population densities continue to put pressure on available water supplies, such that investment in new sources and water treatment facilities is expanding rapidly and will continue to do so for some time to come.

Whether it is to expand the purification of water from existing sources, or to bring on–stream completely new types of supply such as desalination, we find an increasing need for tubes, valves, filters and other components made from stainless steel. Its corrosion resistance is an obvious benefit for such components but so, too, are its ease of fabrication and its cleanability.

A further important consideration is the inert nature of stainless steel from a biological standpoint. Increasingly stringent water purity standards require materials that do not leach into the water significant traces of hazardous constituents.

In this section, papers and other publications describe the many ways that stainless steels help to prevent contamination of our lakes and rivers as well as to treat and distribute the water from our taps that so often we take for granted.

In the 1980s the municipal company, Azienda Servizi Municipalizzati (ASM), decided to exploit the excellent natural water of the Spino springs, even though they lie on the other side of a mountain. The solution was a long, wide pipe. In fact the 3,052-metre-long tunnel, which is 2.65 metres in diameter, can hold 16,800 cubic metres of water. The water flows from the tunnel into a 6,000 cubic metre capacity tank.

This letter by the DWI clarifies the approval status for stainless steel products used in contact with Drinking Water in the UK.

In pure water at normal (ambient) temperatures, stainless steels can be considered "inert". Except for chemically purified waters there are various levels of anions, including chlorides, which can be aggressive to stainless steels under certain circumstances. General corrosion over large areas of the surface is not usually encountered on stainless steels, due to formation and maintenance of an inert "passive" surface layer, but localised corrosion can occur due to the breakdown of the passive layer by chlorides at discrete sites.

Paper by Prof. J. Ledion, Ecole Nationale Sup. d'Arts et Métiers, Paris, France presented at the workshop “Stainless Steel in Drinking Water Applications, Brussels, 19th November 2003, organised by Euro Inox with support from CEOCOR (Brussels) and GfKorr (Frankfurt/M.) Covers the importance of water composition, the aggressiveness of water, the driving forces for corrosion and the corrosiveness of water towards metals.

There is a growing demand for stainless steel rotary-drum thickeners in the wastewater treatment industry, according to Waterlink Hycor Corp. of Lake Bluff, Illinois, U.S.A., one of at least three companies that supply the North American marketplace. To operate efficiently, municipal wastewater treatment facilities must reduce the volume of sewage sludge they store and transport prior to going to landfill.

Paper by J. Baron, CRECEP, Paris (France) presented at the workshop “Stainless Steel in Drinking Water Application”, Brussels, 19th November 2003, organised by Euro Inox with support from CEOCOR (Brussels) and GfKorr (Frankfurt/M.)
It covers European Co-normative research 1995 –1999 and looks at some current EU standards.

Stainless steel pipes for drinking water systems facilitate the job of keeping water clean and quality standards high.

A new technical paper in the Nickel Institute's Reference Book Series has been posted

This document provides information about stainless steel fabrication practices and their implications on corrosion behaviour when exposed to waters and waste waters. Aspects of grade selection guidelines, alloy properties, design and health and safety aspects are also included.

The city of Tokyo has officially adopted corrugated pipes, made of S31600 stainless steel, for new sections of its extensive network of underground potable water pipes.

Nickel Institute reference book series, 1987. Provides engineers with information that allows them to make reasonable preliminary estimates of the manner in which the operating environment is likely to affect performance of the various stainless steel grades available.

Since the late 1960s, over 1600 municipal waste water treatment plants in the USA have been built with stainless steel aeration piping, transfer piping for digester gas and sludge, sliding gates, valves, tanks, screens, hand rails, and other equipment. Stainless steel was selected to reduce the high maintenance and replacement costs associated with less corrosion-resistant materials. Overall experience has been good to excellent.

Paper by Dr. H. Schlerkmann, Mannesmann Forschungsinstitut GmbH, Duisburg and Dr. H. Klemp, Mapress, Langenfeld (Germany) Presented at the workshop Stainless Steel in Drinking Water Applications,, Brussels, 19th November 2003, organised by Euro Inox with support from CEOCOR (Brussels) and GfKorr (Frankfurt/M.) It covers Metallic materials for potable water pipe systems and a Stainless steel pressfitting system for potable water

This excerpt from the ISSF Book of New Applications 2007, gives more information on water applications.

The following are included here:

·         Quick-connect coupler

·         Evaporators for multi-effect distillation

·         Ferritic stainless steel water tank

Stainless steel is being used to solve long-running maintenance challenges at the Huddersfield Waste Water Treatment Works, one of the most heavily loaded in the United Kingdom.

Consumer thirst for bottled water is on the rise. In the United States alone, US$4 billion worth of domestically produced and imported bottled water -- 50.3 litres per capita -- was sold in 1998. There are nearly 1,000 producers of bottled water in that country, and most of their equipment is made with either S30400 or S31600 stainless steel

11019 Stainless Steel Plumbing 10076 Guidelines for the Use of Stainless Steel in Municipal Waste Water Treament Plants 10072 Water Supply Wells for Reverse Osmosis Plants 10003 Reverse Osmosis -- Which Stainless Steel to Use? 12005 A Report on the Performance of Stainless Steel Pipe for Water Supply in Underground Soil Environments 10008 H2O: Nickel's Contribution to Distilled Water, Dams and Condensers

One increasingly popular way to eliminate microbes is to expose them to a lethal dose of ultra-violet (UV) light. This type of electromagnetic radiation causes a photochemical transformation in the nucleic acids of the micro-organisms, reducing their ability to replicate.

This paper summarizes the basic requirements of the material in potable water applications. The paper was produced by The Steel Construction Institute (SCI) on behalf of the British Stainless Steel Association (BSSA). It has been accepted as a code of practice in the UK, but is also useful as an advisory technical document beyond the national context.

The largest water treatment facility in the United States has been completed on schedule, thanks to an automated welding process that is well-suited to joining nickel-containing stainless steel pipe.

In old towns, especially in Europe, where water mains consist of asbestos-cement or cast iron pipes, leaks can result in water losses of up to 40%. In recent years, demand for water in these areas has increased, and civil engineers have found themselves faced with the challenge of how to replace the obsolete pipes economically.

This technical paper reviews the behaviour of conventional stainless steels in freshwater, chloride-containing waters and seawater. Included are the austenitic Types 304 and 316 stainless steels, Type 410 and the ferritic 18Cr/2Mo/Ti stainless steels. Factors of importance for alloy selection are discussed. The paper also considers welded joints, soft soldered joints and brazed joints (Reprinted from Transactions of the 2nd Spanish Corrosion Congress.)

It might take a few years, but stainless steel pipe could become as common in North American domestic water systems as it is currently in Japan or Germany.

This report includes information on the selection and fabrication of stainless steel equipment in distillation-type desalination plants. An in-service test for stainless steels was provided by a three -year study of the operation of a 11 000-litre per-day distillation plant in Freeport, Tx, U.S.A. Photographs show typical details of the test plant and specific corrosion problems that were encountered in its operation.

Paper by P.-J. Cunat, Euro Inox, Brussels (Belgium), presented at the workshop “Stainless Steel in Drinking Water Applications”, Brussels, 19th November 2003, organised by Euro Inox with support from CEOCOR (Brussels) and GfKorr (Frankfurt/M.) Covers  electrochemical investigations and discusses the passivity phenomenon, the critical pitting potential, the open circuit potential (OCP) and metal leaching experiments

High-nickel austenitic stainless steel S34565, which contains 17% nickel, may be the solution to some of the corrosion challenges facing operators of desalination plants worldwide.

Paper presented at the workshop “Stainless Steel in Drinking Water Applications”, Brussels, 19th November 2003, organised by Euro Inox with support from CEOCOR (Brussels) and GfKorr (Frankfurt/M.) Covers  the limitations of conventional systems,  the characteristics of stainless steel solutions and practical aspects of the lining process

Paper by Dr. V. Boneschi, Centro Inox, Milan (Italy) and Dr. A. Quazzo, SMAT S.p.A., Turin (Italy). Presented at the  workshop “Stainless Steel in Drinking Water Applications”, Brussels, 19th November 2003, organised by Euro Inox with support from CEOCOR (Brussels) and GfKorr (Frankfurt/M.) Covers  types of stainless steel used in the water cycle and refers to relevant hygiene, release, laws and standards. Also illustrates recent examples of applications in Italy with reference to specific case studies.

Discusses the use of welded stainless steel piping in types 304L and 316L which has been successfully used in over 100 PWTPs and related potable water applications in North America. Stainless steel has been used since 1965 for the large, central-control, gravity filter in water treatment plants with good performance in over 75 installations.

The following are being discussed:

·         Functional aspects

·         Architectural features

·         Environmental qualities

·         Choice of grade and surface

·         Applications (roof geometries, bitumen-felt roofs, historic monuments)

·         Guidelines (tools, forming, soft-soldering, adhesive bonding, fixings)

·         Accessories

Paper originally delivered at the BSSA Conference 'Stainless Solutions for a Sustainable Future' held in Rotherham on 3rd April 2003. Stainless steels are used extensively throughout the Changi water plant that will provide a long-term sustainable future for the citizens of Singapore throughout this century. The role of stainless steels in Nuclear Reprocessing Plant, Desalination Plant and other water treatment projects is also touched upon briefly.

Paper by Dr. P. Cutler, Nickel Development Institute, Birmingham (UK) presented at the workshop “Stainless Steel in Drinking Water Applications”, Brussels, 19th November 2003, organised by Euro Inox with support from CEOCOR (Brussels) and GfKorr (Frankfurt/M.). Discusses the reasons why stainless steels are used in drinking water applications and covers grade selection, life-cycle cost benefits and design and fabrication aspects.

Stainless steel pipes circulate water through tubular reactors, custom-built of stainless steel. The reactors contain a patented device that uses ultraviolet light to destroy contaminants.

Presentation on the occasion of the workshop “Stainless Steel in Drinking Water Applications”, Brussels, 19th November 2003, organised by Euro Inox with support from CEOCOR (Brussels) and GfKorr (Frankfurt/M.)

The next century will doubtless transform our world in ways we can't even begin to imagine. But that hasn't stopped some from predicting that, with the global population showing no signs of abating, the pressure on our natural resources will only intensify, and that the most sought-after natural resource in the twenty-first century will be water.

Water is mankind's most precious resource. Stainless steel is an ideal material to handle this element of life. Let us take you on a guided tour of the applications of stainless steel in a water context.