A Spectrum of Water Treatment: Ensuring Safe and Reliable Water 

By Andy Smith, Drinking Water Treatment Practice Area Lead

When you pour yourself a glass of water, do you ever pause and think about where the water came from? If you do, what type of setting do you imagine? An aquifer deep underground? A slow, wide, meandering river snaking through farmland? A pristine alpine lake?

The truth is that in the West, the origins of the water we drink are as varied as the communities that we serve and serves as a reflection of the kaleidoscope of landscapes and climates that we occupy. And as water treatment engineers, it is imperative that we understand the differences that these origin stories create in the ways in which we treat our drinking water to ensure safe, reliable supplies for customers like you and me. With that in mind, let’s take a moment to consider the various principles and objectives we must satisfy when developing and evaluating drinking water treatment approaches.

Regardless of what we’re treating, and for whom the water is for, drinking water treatment is ultimately beholden to the principle that water should not contain any contaminant in a concentration greater than what regulators have found to be harmful to human health.

The first step in determining how to treat a water source is to assess the types of contaminants present in the “raw” or untreated water. The types of contaminants we find and must treat for are strongly influenced by the nature of the water supply. Surface waters, for instance, are typically low is dissolved minerals but higher in suspended solids, dissolved carbon compounds, and microbial pathogens. Groundwater, on the other hand, tends to be low in suspended solids, carbon, and microbes, but higher in dissolved minerals and solids, and occasionally in certain manmade particles that tend to find their way into aquifers.

Once we understand the contaminants present in the source water, we can begin to develop alternative processes capable of reducing the concentrations of undesirable constituents to safe levels. However, our evaluation doesn’t stop there – often, the agency supplying the treated water to customers will have specified treatment goals that may be supplemental to the types of treatment that may be prescribed strictly to meet regulations. Or, a community may have specific goals that have more to do with the aesthetics of the water supply (think of the ways that treated water can taste, smell, and look differently) than with the safety of the water.

The practical implications of these considerations – the unique combinations of raw water characteristics and contaminants, the regulatory-driven requirements to meet drinking water standards, and any agency-specific treatment objectives for tailoring treated water quality – will manifest themselves in the configuration and complexity of the treatment system. Our job as treatment engineers and scientists is to guide our clients through this complex web of considerations and deliver a treatment system that is customized to an agency’s needs, and to the ultimate imperative of ensuring safe and reliable drinking water to people like you and me.

By Andy Smith, Drinking Water Treatment Practice Area Lead

Andy Smith has performed a wide variety of planning and design work for numerous water and wastewater treatment facilities for agencies in California and Oregon. His treatment facility experience includes master planning and predesign, detailed design and cost estimating, and engineering services during construction. His treatment expertise includes preliminary treatment, clarification, filtration, disinfection, chemical storage and metering, pumping stations, solids handling, and dewatering.