How Clean is Our Water?

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The confluence of two recent events – a trip to the local grocery store and our company’s relationship with the charitable organizationWaterAid– inspired our investigation of several types of bottled and surface waters. Here’s what our initial analysis revealed.

Bottled and Tap Water Samples

In the U.S. and other developed countries, drinking water – whether it comes from local municipalities via the tap or from manufacturers that bottle it at the source – is carefully regulated, widely available and often taken for granted. Using an海洋高清光谱仪，我们很好奇测量一些样本以确定任何频谱差异。

We began with several bottled water samples from a local grocery that’s part of a bigger chain in the southeastern U.S. First up: spring water. According to the U.S. Food and Drug Administration, spring water is “derived from an underground formation from which water flows naturally to the surface of the earth.” These spring water samples appeared to vary in composition (sometimes dramatically) depending on what facility they came from (Figure 1).

Figure 1.杂货店品牌泉水

接下来，我们测量了饮用水，这是用于饮料或食物准备水的水。我们来自同一杂货店的饮用水样品显示出比在春水中更多的紫外光谱活性（图2），这表明可能存在更多溶解的固体和/或有机物。

Figure 2.杂货店品牌饮用水

为了进行比较，我们还测试了当地的自来水样品。它的紫外线峰低于瓶装水，但在240-290 nm的活动中显示出更多的活性（图3）。这可能是由于在管道中加入氟化物和痕量污染物等水处理的可能导致的，这些污染物是从处理设施中输送水的。

Figure 3.Municipal (tap) water, St. Petersburg, Fla.

To round out our survey of regulated water sources, we measured a sample of an expensive bottled water brand. Although this water is about 6x the cost for a case (24) of 16.9 oz. (500 ml) bottles, the expensive-brand samples we tested had very similar spectral characteristics as the store-brand spring water samples (Figure 4). Consumers don’t seem to mind the extra expense – according to several sources, the top bottled water brands have annual sales in the billions.

图4。High-end bottled water

融雪，地面雪和湖水样品

为了更好地欣赏较不发达国家的许多人经历的水质（或缺乏水质），我们还在两个截然不同的地区测试了来自美国两个独立地区的地表水。

In the Pacific Northwest, we tested both snowmelt (Figure 5) and ground snow (Figure 6) collected on or near Mt. Spokane, Washington. For context, Mt. Spokane has an elevation of nearly 6,000 ft., averages about 163 inches (413 cm) of snowfall annually, and is about 35 miles from Spokane, a city of approximately 220,000. Interestingly, the Mt. Spokane water samples were very similar spectrally to the grocery store spring water and drinking water samples.

图5。Snowmelt, Mt. Spokane, Wash.

Figure 6.地面的雪,太。Spokane, Wash.

In contrast, the sample we collected from a Florida lake had such a strong response in the UV that the spectra are off-scale (Figure 7), which is suggestive of contaminants. It’s only when we rescale the results that we can fully appreciate the dramatic difference (Figure 8). This water quality level is similar to – and in many cases, better than – the only water available to nearly a billion people around the world.

Figure 7.Lake water, St. Petersburg, Fla.

Figure 8.All water samples

但是，像Wateraid这样的组织正在帮助弥合全球十分之一的人的差距，而无需获得清洁水。

About WaterAid

WaterAidis one of several international, charitable organizations dedicated to making clean water, decent toilets and good hygiene a normal part of everyday life for people everywhere. In conjunction with our parent companyHalma plc，海亚博最新网站多少洋洞察力正在支持代表Wateraid的筹款活动生命的水. The aim of this campaign is to transform lives in eastern India by bringing clean water to 8,000 people in比哈尔, a remote area with limited access to safe drinking water.

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