Why real-time sensing?

We cannot survive without water as it affects almost every aspect of our life. With growing population and increasing demand for better life quality, the need for clean and safe drinking water continues to rise. Various contaminants, including heavy metal ions (e.g., lead, mercury, and arsenic), are widely present in water systems [1]. Heavy metal ions are toxic and may cause serious damage to organs, tissues and bones, and nervous systems of humans. For example, Lead can accumulate in the body’s soft tissue and bones; lead poisoning, to which children are particularly vulnerable, damages brain and many internal organs (e.g., heart and kidneys) and disrupts body processes.

Water commination may happen at any part of the water supply system (public or private), from the source and intake, to the treatment facility, to the distribution system, and to the point of use. For the public water supply systems, current water quality monitoring mostly occurs at the water supply intake or water treatment plant, instead of along water distribution lines and at the point of use, which is problematic given potential changes in water quality and associated risks within water distribution systems, particularly those aging systems with unsafe lead-containing pipes and fittings. The nationwide public is having an increasing concern over water safety, alerted by recent large-scale water catastrophes. For example, the water crisis in Flint, Michigan has resulted in a range of serious health problems for as many as 8,000 children due to their exposure to contaminated drinking water with unsafe levels of lead, which was caused by the corrosion of water delivery pipes [2, 3]; the chemical spill disaster in West Virginia led to water contamination impacting over 300,000 residents [4].

On the other hand, private wells are used by more than 15 million U.S. households as the water source [5], but they are NOT regulated by Environmental Protection Agency (EPA) and may be at risk for contamination due to ground water pollution and/or safety issues within the supply system. Homeowners are responsible for their well water safety, but they are reluctant to test water quality on a regular basis due to the inconvenience and high cost burden of laboratory-based test practice. Therefore, it is crucial to monitor contaminants such as toxic heavy metal ions for the entire supply system (i.e., from source to tap), particularly at the point of use, so that we can provide early warning of contamination in water and thus improve water safety and public health benefits. This requires accurate and accessible detection technologies to ensure real-time, in situ water quality monitoring and early warning capabilities to avoid public safety catastrophes.

[1]. EPA. Table of Regulated Drinking Water Contaminants. 2016.

[2]. Hanna-Attisha, M., J. LaChance, R.C. Sadler, and A. Champney Schnepp, Elevated Blood Lead Levels in Children Associated With the Flint Drinking Water Crisis: A Spatial Analysis of Risk and Public health Response. American Journal of Public Health, 2015, 106(2), 283-290.

[3] The New York Times. Unsafe Lead Levels in Tap Water Not Limited to Flint. 2016.

[4] NBC News. West Virginia Chemical Spill Cuts Water to up to 300,000, State of Emergency Declared. 2014.

[5] EPA. About Private Water Wells. 2015.

As citizens in Flint, Michigan, wait for the government to fix the problems that led to lead contamination in their drinking water, they and many others doubtless wonder how communities can protect themselves in the future.

Centralized water systems put control of water treatment and testing in the hands of skilled professionals using sophisticated equipment. But the crisis in Flint has shown that those systems alone are not enough to safeguard our drinking water. One improvement would be installation of sensors that provide immediate and unambiguous answers about water purity.

Many Flint residents knew they had lead in their tap water last year, but they didn’t know how much. Sensor technology being developed at the University of Wisconsin-Milwaukee immediately indicates the amount present, whether it’s only 1 part per billion or far above the limit of 15 parts per billion set by the Environmental Protection Agency.

That type of technology could have alerted Flint residents the minute contamination occurred, and it can help protect the millions of Americans who still get their water from lead pipes. In Flint, contamination occurred when corroded pipes leached lead into tap water.

That has led to calls to replace the nation’s aging infrastructure – a costly and disruptive proposition. Total replacement also is unnecessary if we can use sensors to identify problem spots and target upgrades.

A number of research teams across the country are already working on this technology, which is encouraging. Those teams include scientists and engineers at UW-Milwaukee, where we are fortunate to have partners in private industry who can help bring our system to market.

Our researchers used nanomaterials to produce a low-cost and highly sensitive mechanism to detect heavy metals in water with selectivity even at very low concentrations.

The technology does not require special training to use. People will be able to test their tap water the same way diabetics use glucose monitors to check their blood sugar levels in real time. Anyone can place a drop on a test strip.

We’ve developed two methods of detection: a hand-held device for single-use testing in the field or in residential homes, and a network of tiny sensors that can be immersed in liquid for continuous monitoring.

We are in the process of testing our sensors with tap water samples taken from Flint during the first half of 2016, in a RAPID study to be funded by the National Science Foundation.

Along with the potential to monitor water quality in municipal water systems, the technology provides a fast, affordable alternative to the current, days-long process for testing private wells.

The individual sensors are very small – hundreds of them occupy a 4-inch-wide silicon wafer. They can be integrated at various locations into existing pipes and equipment to sound the alarm wherever and whenever contamination occurs.

With federal and state funding available to replace Flint’s corroded pipes, an opportunity exists for the city to become the first in the nation to take advantage of this new water-monitoring capability.

Even more exciting, the sensors can be “tuned” to rapidly signal the presence of other chemicals and potentially waterborne bacteria in addition to heavy metals. We can envision sensors throughout a waterworks system that monitor multiple kinds of contaminants simultaneously.

Eventually, the same kind of technology could be used to integrate water and energy systems, creating “smart” systems that conserve both resources.

The development of these sensors is an example of how research collaboration between the public and private sectors can speed commercialization of new technology. UW-Milwaukee faculty worked with water business partners in a National Science Foundation-backed research consortium to identify technologies with the strongest commercial appeal and then build prototypes.

But more resources are needed to expedite technologies such as ours to the market. And, once it’s available, the technology should be adopted as part of standard monitoring procedures to better assess public health and exposures to contaminants.

Squabbling began almost immediately over who is to blame for the contamination in Flint. But Americans’ health and well-being is too important to get lost in the finger pointing. Instead, we should focus our attention and our resources, both public and private, on making tools that safeguard community health widely available.

  • * Reprinted from Milwaukee Journal Sentinel (March 2016)