When is water safe to drink? - Mia Nacamulli

翻译人员: Yi Fan 校对人员: Lipeng Chen

Take a look at the water in this glass.

我们来看一下这杯子里的水。

Refreshing, hydrating, and invaluable to your survival.

清爽又补水， 对生存至关重要。

Before you take a sip, though,

但是，在喝之前，

how do you know that the water inside is free from disease-causing organisms

如何确定水里没有致病微生物

and pollutants?

以及污染物呢？

One out of ten people in the world can't actually be sure

这世界上10人中有1人无法确定

that their water is clean and safe to drink.

自己喝的水是否干净又安全。

Why is that?

为什么？

Inadequate sanitation,

卫生系统不完备，

poor protection of drinking water sources,

水源保护缺失，

and improper hygiene

以及不正确的卫生规范

often lead to sewage and feces-contaminated water.

常常会导致污水 或者受排泄物污染的水产生。

That's the ideal breeding ground for dangerous bacteria,

这对一些有危害的细菌，

viruses,

病毒，

and parasites.

和寄生虫来说是一个绝佳的繁殖地。

And the effects of these pathogens are staggering.

这些病原体对人体的影响是令人震惊的。

Diarrheal disease from unsafe water is one of the leading causes of death

不安全的水所导致的腹泻

是全世界5岁以下儿童群体中的一大死因。

around the world for children under five.

一份联合国2010年报告显示，

And according to a U.N. report from 2010,

microbial water-borne illnesses killed more people per year than war.

每年，以水为传播媒介的微生物疾病 造成的死亡人数甚至超过战争。

Proper treatment processes, though, can address these threats.

但是，一些正确处理水的步骤 可以让我们躲过这些威胁。

They usually have three parts:

这其中包括三部分：

sedimentation,

沉淀，

filtration,

过滤，

and disinfection.

以及消毒。

Once water has been collected in a treatment facility,

一旦水被收集在处理设备中，

it's ready for cleaning.

就可以开始净水了。

The first step, sedimentation, just takes time.

第一步，沉淀， 这只需要时间。

The water sits undisturbed, allowing heavier particles to sink to the bottom.

水被静置， 使较重的颗粒沉淀到水池底部。

Often, though, particles are just too small

但很多情况下，这些颗粒都太小了，

to be removed by sedimentation alone

通过沉淀无法完全去除，

and need to be filtered.

需要进一步过滤。

Gravity pulls the water downward through layers of sand

重力使得水向下流过一层层沙子，

that catch leftover particles in their pores,

这些剩余的颗粒 便被留在了沙子的孔隙中，

prepping the water for its final treatment,

为净水的最后一步做好了准备。

a dose of disinfectant.

最后一步，消毒，

Chemicals, primarily forms of chlorine and ozone,

使用主要由氯气和臭氧等化学物质构成的消毒剂，

are mixed in to kill off any pathogens

杀灭所有的病原体，

and to disinfect pipes and storage systems.

消毒水管和储水系统。

Chlorine is highly effective in destroying water's living organisms,

氯气可以有效杀灭水中的微生物，

but its use remains government-regulated

但是氯气的使用仍然受到政府的管制，

because it has potentially harmful chemical byproducts.

因为它会产生具有潜在危害的化学副产品。

And if an imbalance of chlorine occurs during the disinfection process,

一旦在消毒过程中 氯气使用过多或过少，

it can trigger other chemical reactions.

这就会引发别的化学反应。

For example, levels of chlorine byproducts,

例如，氯的副产品三卤甲烷，

like trihalomethanes, could skyrocket, leading to pipe corrosion

其含量会剧增， 从而腐蚀水管，

and the release of iron, copper, and lead into drinking water.

铁、铜等元素会被释放进饮用水中。

Water contamination from these and other sources

水污染还会在这样或那样的源头产生，

including leaching,

包括农药渗流，

chemical spills,

化学物质排放，

and runoffs,

以及各种径流污染，

has been linked to long-term health effects,

这些水污染与一些长期健康危害有关，

like cancer,

比如说癌症，

cardiovascular and neurological diseases,

心血管疾病以及精神损伤，

and miscarriage.

还有流产。

Unfortunately, analyzing the exact risks

不幸的是，想要分析出 喝了这被化学物质污染的水

of chemically contaminated water is difficult.

将会带来哪些确切危害， 是很困难的。

So while it's clear that disinfectants make us safer

尽管消毒可以把致病病原体都消灭，

by removing disease-causing pathogens,

让我们喝的水更安全，

experts have yet to determine the full scope

专家们还没有能够确定

of how the chemical cocktail in our drinking water

饮用水中的化学物质

really impacts human health.

可以在多大程度上影响我们的健康。

So how can you tell whether the water you have access to,

那么，如何分辨身边现有的水

whether from a tap or otherwise,

是否适合饮用呢？

is drinkable?

Firstly, too much turbidity,

首先，浑浊度过高，

trace organic compounds,

微量有机化合物过多，

or high-density heavy metals like arsenic, chromium, or lead,

或者含有高浓度的砷、铬、铅等重金属，

mean that the water is unsuitable for consumption.

意味着它不适合饮用。

A lot of contaminants, like lead or arsenic,

许多污染物，例如铅和砷，

won't be obvious without tests,

不通过测试是看不出来的，

but some clues, like cloudiness,

但是有一些小线索， 比如说浑浊，

brown or yellow coloration,

液体呈棕色或黄色，

a foul odor,

散发难闻的气味，

or an excessive chlorine smell

或者明显的氯气味，

can indicate the need to investigate further.

告诉我们这时需要进一步测试。

Water testing kits can go a step further

水污染测试用具可以帮助我们

and confirm the presence of many different contaminants and chemicals.

证实各种污染物 和化学物质的存在。

With many types of contamination,

面对各种污染，

there are ways of treating water where it's used instead of close to its source.

人们很多时候选择在 用水环节净化而非从水源地着手。

Point-of-use treatment has actually been around for thousands of years.

这种在用水环节净的方法 已经存在几千年了。

Ancient Egyptians boiled away many organic contaminants with the sun's heat.

古埃及人用太阳照射的热量 蒸发掉水中很多有机污染物。

And in Ancient Greece, Hippocrates designed a bag

在古希腊，希波克拉底 设计出了一种过滤袋，

that trapped bad tasting sediments from water.

把水中的异味沉淀物留在袋子里。

Today, point-of-use processes usually involve ionization

现如今，在用水环节净水， 通常使用的是电离法，

to lower mineral content.

以此来降低水中矿物质含量。

They also use adsorption filtration,

或者用吸附过滤法，

where a porous material called activated carbon

有一种叫活性炭的孔状材料，

strains the water to remove contaminants and chemical byproducts.

它可以过滤出水中的污染物 和化学副产品。

While it's not always an effective long-term solution,

尽管这不是一种有效的长期策略，

point-of-use treatment is portable, easy to install, and adaptable.

但是它轻便，安装方便， 并且适应各种环境。

And in regions where large-scale systems are unavailable,

有些地区没有大规模的净水系统，

or where water has been contaminated further along its journey,

或者水在运输过程中就被污染了，

these systems can mean the difference between life and death.

那么这时候，这些轻便的净水设施 就可以决定着人们的生死。

Clean water remains a precious and often scarce commodity.

干净的水至今依然是一种宝贵又稀有的资源。

There are nearly 800 million of us who still don't have regular access to it.

地球上有8亿人还不能每天喝上干净的水。

The good news is that continued developments in water treatment,

好消息是不断进步的水处理技术，

both on a large and small scale,

无论是大范围的还是小范围的，

can alleviate a lot of unsafe conditions.

已经可以减缓 很大一部分不安全的因素。

Implementing proper systems where they're needed

在有需要的地方配置净水系统，

and paying careful attention to the ones already in place

对已投入使用的净水系统进行维护，

will fulfill one of the most basic of our human needs.

这简单的两件事就可以满足 我们人类最基本的需求之一了。