Point-of-use technoliges can help decentralize water treatment.

Water is getting more complex, in part, because of higher scrutiny from science. Water quality testing equipment. Photo by Mary Hollinger, NODC biologist, NOAA.
Water is constantly in the news. Unfortunately, lately the news about water seems to be all negative - contaminants, shortages, legal battles over water rights, etc. It sounds as if we are facing a huge problem, and more of the same for the near future.

The positive news, however, is that where there are problems, there are opportunities for those willing to learn more about the situation.

The public's understanding about water conditions generally comes in the form of “sound-bite” education from media outlets. We all tend to know something about some high-profile contaminants in water. In the last six months, for example, you may have heard or read about perchlorate (a rocket fuel component), lead, teflon (“no-stick” water) and/or arsenic. The list goes on.

In some cases, the contaminant simply is a result of Mother Nature. In many other cases, the source for contamination is based on human activities, or our best intentions going the other direction. A classic example is methyl tertiary butyl ether (MTBE) - an oxygenate in gasoline. Intended to make gas burn cleaner, MTBE now has shown up in the ground water of at least 40 states. MTBE tends to be more mobile in water than the other components of gasoline-related contamination and is more difficult to remove than many other contaminants.

Foreign and complex substances are being detected at lower and lower levels, and are being found to have effects on living organisms, large and small, at equally low concentrations.

In other words, water is getting more complex, in part, because of higher scrutiny from science.

Keeping Up

Then there's higher scrutiny from government regulations. Municipalities are under increasing regulatory pressure. Regulatory analysts note that water regulations are getting more complex and that “future regulations promise even more complexity.” What's more, the pace of regulation also is accelerating. The American Water Works Association notes that whereas nine regulations were finalized in the 17-year period from 1975 to 1992, 10 new regulations were finalized over a six-year span from 1998 to 2004.

In other words, more “ink” is being devoted to regulating each contaminant.

This higher scientific and regulatory scrutiny adds up to a seemingly impossible task we entrust to municipalities. The methods municipalities use to treat water almost always are centralized at a water treatment plant in which 100 percent of the water is treated to a good quality, and then pumped into a distribution system.

POU devices, like this one from APEC, are miniaturized versions of centralized treatment.

New Paradigm

Let's take a look at why a new, “decentralized” approach may work better. Back in 2001, the U.S. Environmental Protection Agency (EPA) promulgated a change in the maximum contaminant level (MCL) for arsenic in water. The change was as a result of a review of health data that indicated lowering the MCL from 50 parts per billion (ppb) to 10 ppb could reduce the number of cases of liver and stomach cancer, diabetes and even heart disease.

This change means that by the compliance deadline of Jan. 23, 2006, municipalities will have to meet the 10 ppb limit for arsenic in water. Specifically, more than 4,000 small systems will have to adopt some method of treatment to reduce the amount of arsenic in their water. For these systems, the centralized approach can be expensive - especially when you consider that we typically ingest (through cooking or drinking) less than 2 percent of that water. The remaining 98 percent is irrigated, flushed or otherwise sent down the drain.

This is exactly why several municipal demonstration projects and studies have been undertaken to show that technologies used at the point of use can reduce the amount of arsenic ingested by the consumer to levels well below the new MCL.

This decentralized treatment uses “point-of-use” (POU) technologies. Here's how decentralized treatment would look: In a small community, homes and businesses can be outfitted with one or more POU treatment units for removal of arsenic wherever water is drawn for consumption or cooking, typically a kitchen tap or drinking fountain. These POU devices could be under-sink reserve osmosis, small in-line cartridges containing arsenic-removing filter media, etc.

Two other drivers are helping move the concept of decentralized treatment forward:

Regulatory guidance from the EPA is evolving, enabling municipalities to change their water treatment thinking and apply more efficient water treatment scenarios.

POU devices essentially are miniaturized versions of centralized treatment that often are capable of removing multiple contaminants from the small fraction of water that is consumed.

These facts eventually should enable municipalities to install, or contract with a company to install and/or maintain POU devices for arsenic removal.


Now, consider the regulatory pressures discussed above and the myriad of contaminants appearing in water. This thinking can be applied to a larger spectrum of contaminants or a combination of contaminants. Radium, nitrates, uranium, lead and many more also may be candidates for decentralized removal to the benefit of the municipality and the public.

Undoubtedly, more exotic contaminants, and lower permissible levels of contaminants, will require more innovative approaches for removal. Innovation will require some study on the part of those who want to be innovators and take advantage of new technologies, applications and opportunities.

When all is said and done, one other factor will drive the change described above - the consumer. Data shows that if the consumer knows a contaminant is there, he or she wants it out. As consumers of water ourselves, we easily can relate to this sentiment. Water system professionals need to prepare for the future opportunities in water treatment.