Rainwater - Why is it Safe?

There are so many misconceptions in the world – and rainwater is no exception. When people think of rainwater, they often think of wastewater, pollutants and even balding! Do you think these ideas are accurate? Whilst such concerns might stem from a common misunderstanding, we seem to accept them as scientific fact.  In this chapter, the truth will be exposed: rainwater is actually extremely clean and safe.

Rainwater is originally beneficial

Let's look back on the days before pollution was such a big issue. We don’t even need to look that far back. How about the 1960s-1970s? Neighborhood children were playing in the streets, never too concerned about finding water. There was never any shortage – mountain valleys, wells and pumps were always accessible. Besides, every time it rained, they could simply look up at the sky, open their mouths and catch the rainwater!

But what do children today do when it rains? They run inside, thinking of their parents’ warnings, “Don’t stay out in the rain! Rainwater is filled with pollutants … it might make you turn bald!”

Well, why don’t we picture something else? Think of a family picnic in the park. - Groups of people sitting on the grass, having lunch with their bottles of water (“bottled water”). As bottled water goes through a ‘purifying process’, people assume it is the safest form of drinking water.

But what if I ask them to drink rainwater? Whilst they might think it a strange idea, there is evidence to show that the bottled water they are drinking actually started life as rainwater.

Yes. The bottled water that we consider to be the purest form of water actually comes from rainwater. In fact, this does not just apply to rainwater; all water, including water from taps, valleys and rivers stems from rainwater. Let’s track the root, using tap water as an example:

Tap water - Water pipe - Filtration plant - Water intake system - The river or Lake -  Water from the valley - Rainwater.

See, this process ends with rainwater.

When we look at the circulation of water in the natural world, the position of rainwater is at the top of the cycle. It is possible, therefore, for us to drink untreated rainwater. This is because rainwater is pure, distilled water evaporated from the sun - nothing else.

However, when rainwater falls from the sky, substances from the air and land melt into the rainwater. Fortunately, when rainwater soaks into the ground, it then becomes mineral water. This water (groundwater) is relatively safe for drinking. However, rainwater that falls to the ground does not just get absorbed into the soil - it goes everywhere. If it falls on waste, it then becomes wastewater as it is contaminated. It can also flow through the sea and into river systems.

As rainwater disperses, more pollutants are added and the water becomes more obsolete. We then pay a high price for purifying it.  This is the simple truth. It seems that the answer to this problem is obvious. The cleanest water is rainwater that has not reached the ground. Rainwater is naturally good - so we need to find a way of catching rainwater before it gets contaminated.

However, it is hard for us to imagine washing our faces or having a bath with rainwater, not to mention drinking it. But, we need to save water since water shortages are a serious problem. In addition to relieving water shortages, rainwater can prevent flooding and droughts. It can also reduce river pollution, and prevent groundwater from becoming contaminated. Moreover, we can reduce the heat island effect in cities, making a pleasant urban environment.

Aren’t you wondering how rainwater deals with these so many issues?

It is time to eradicate the “ignorance of water”

We use the word “illiteracy” indicating a lack of ability to read and write. Which is more serious, “illiteracy” or an “ignorance of water”?

In 2003, UNDP (United Nations Development Program) presented HDI (Human Development Indicators). According to this data, the Adult literacy rate of South Korea is 97.9%. In other words, the Adult illiteracy rate of our country is only 2.1%. This percentage indicates that South Korea is the country that has the lowest illiteracy rate worldwide. This fact could be attributed to the effort of King Sejong who made the most scientific letters in the world, “Hangul”.

Korea’s Adult illiteracy rate (2.1%) may include the elders who could not be educated living in poverty. Even though they had inconvenience due to their illiteracy, it would have had little to do with the Korean War, threat to life, or starvation.

However, water is a totally different problem. First of all, all living things cannot live a day without water. Our body is composed of 70% of water. We become unconscious without 5% of water, and lose our lives without 12% of water. So we can endure 4-5 weeks without food but cannot stand only one week without water. Our daily life also stops without water. If water does not exist, we cannot cook, dispose excrement, do the laundry, and clean up a house. Farmers cannot work on a farm. Wars competing for water break out between Africa tribes suffering from water shortage and causing many people to get injured.

Then, how much do we know about water, which is inevitable in our lives? That is to say, what would be our country’s Adult “ignorance-of-water rate”? I will show several examples.

As I mentioned above, we use rainwater purified after falling on the ground and getting dirty. This fact is thought to have originated from distrust of safety of rainwater, but when we examine the other side, there is the logic of interest among groups concerned with water.

Another point is about the amount of water use of our country. We often say we waste water as we use water. That is not completely false. The government report demonstrates that Koreans use more water than do people in other countries. However, is it true? Was data from the report compared correctly with the amount of water use in other countries? It is hard to find people who are economical as much as Korean housewives are. Let’s see more scientifically by calculating the amount of water we use each day.

For example, we can notice that water rate and water usage are marked with “m3” unit in water bills. If we divide it by 30 days and the number of family, we would get the amount of water a person uses per day. When we look into it more carefully, this figure is smaller than what the government reports. From this simple figure, we will realize what the problem is.

By the way, there is something that Koreans misunderstand. It’s about acid rain. The fact that is universally known and accepted among people that is rain causes bald heads. You would have heard that statues get eroded because of acid rain. The story of acid rain is published in elementary school textbooks. Of course, it is written in a negative way that acid rain is bad. However, these are huge misunderstanding and stereotypes. Let’s talk about the conclusion first. Rain contains acidity but its level is not harmful to our body. The story of acid rain will be explained in the next chapter.

It is hard to express in numerical values, but Adult ignorance-of-water rate is quite high. However, the problem of lack of knowledge about water is not limited to our country because water management has been processed only by experts in several countries. These days, however, comprehensive water management as an alternative to overcome this matter is raised. This trend is to spread and enlighten the water issue to local residents as well as experts. This is clearly a paradigm change. This story was discussed in “The second World Water Forum” that was held in The Hague in 2000. The conclusion is making water everybody’s business. This is the global promise to root “ignorance of water” out. I hope this promise is kept in our country. In short, we should understand water properly from environment, development, industry, and education policies, and lead participation of local residents. Now you are a water agent.

We are looking for someone who became bald because of acid rain

It’s raining. When it rains, I open a window and drink rainwater from my hands. Are you wondering how I could do so? As I said earlier, rainwater is the most pure distilled water in the world.

However, when I look out of the window, there are people running here and there to avoid the pouring rain. People who are running the best among them do not have much hair. When they are asked the reason why they ran so hard, most of them would answer such as “Isn’t it too obvious that we should run in the rain? I will lose my hair,” and they would look at me in a very strange way.

Many people would also agree with these people. Everyone thinks that the rain is a pollutant that we should deal with as soon as possible. If I tell them that I usually make tea with rainwater, they will frown at me.

To be honest, it is true that rainwater is acid. The acidity of clean water is 5.6pH and almost all the rain in the earth is acid. If the region it rains on has the source of the air pollution, the acidity would be stronger so the level of pH will be 3-4pH (The acidity is stronger as the value of pH gets lower). However, after another 20 minutes of rain, the acidity becomes far weaker than before.

Some impatient people will tell me again that it is true that rainwater is acid. However, they will change their thoughts after they hear about how less dangerous the acidity of rainwater is compared to other things.

The acidity of liquids we encounter everyday is far higher than rainwater. The acidity of Cola, a typical carbonated drink, is 2.5pH and that of a shampoo and a conditioner is 3.5pH. Especially yogurt, which is children’s favorite snack, has 3.4pH, and a pH of juice is 3.0. (Then, you might argue that the acidity difference between these items and rainwater is just 2-3pH. In this point, however, although the numerical difference is small, the acidity difference is in fact huge.) No parents worry about the acidity in the juice and yogurt their kids drink every day. Then why are we afraid of rain, whose acidity is far weaker than that of beverage? The answer is our lack of knowledge.

Rainwater Research Center in Seoul National University investigated how much the acidity of rainwater is dangerous. We measured the pH of rainwater from a gutter of the roof. Then, during the short period of time while rainwater passes through the roof, its pH changed into 7-8.5 alkaline reactions. This figure is not related to our health and thus rainwater is safer than juice, yogurt, a shampoo and a conditioner. An experiment has shown that washing hair with rainwater is good for our hair and there is no problem with the acidity of rainwater. 

After 2-3 days, we measured the pH of rainwater again, and it was already neutralized! Since we don’t use rainwater right after we get it but after it’s gathered, there is nothing to worry. We can save water costs by cleaning a room and watering the flowers with this gathered water. If you are still concerned about this, boiling the water is another way.

It has rained everywhere from the past, but why do especially Koreans have an aversion to acid rain, which was not a problem in the past and in other countries? When I went to Tokyo to attend the International Rainwater Forum, Japanese housewives were treating guests with tea made up of rainwater. Someone introduced a device that operates a portable water purifier using a hand pump or a pedal so that they can filter out rainwater without electricity in emergency.

In this way, many countries including Japan use rainwater universally in everyday life. Among them, Germany, who is one of the developed countries, uses rainwater in many fields in their daily life.

I hope you do not consider acid rain seriously anymore. If there is a problem, we can deal with it wisely. So rainwater is not a disaster, but a gift and a blessing from the sky.

If there is someone who thinks they became bald because of acid rain, how about raising funds that offer medical expenses and compensation? But if they want to be covered by this fund, they should prove an obvious and scientific causal relationship between baldhead and acid rain. Fund raising can be covered by 1/100 of budget invested in wastewater management.

Now you do not need to run in the rain. You might catch a cold but you won’t become bald because of rain. If you still have doubts although you were not available for being rewarded from “Baldhead fund” since you were fail to prove scientific relationship between baldhead and acid rain, come and see me. I will give you a wig as a gift that is completely strong enough for acid rain.

A queen’s mineral water

If the queen from the Snow White story were born these days, she would also have doubts about water. She may say “Mirror, mirror, what is the most pure water in the world?” instead of asking the most beautiful woman in the world. For this woman who has so many worries about safety, which water will be the best? Expensive bottled water from abroad? Or, water from a mountain valley? Or, natural aquifer under the ground advertised in a beer commercial on TV? Among them, if the safest water is proved scientifically, the queen will try to get it at any cost. However, what is the possible way of getting water for ordinary people?

I will explain how safe and clean rainwater is with a scientific story. There are several ways to express the pureness of water, and TDS (Total Dissolved Solids) is one of them. This is an indicator indicating the amount of foreign substance dissolved in water. It is a somewhat difficult term, but this is the amount of remaining sludge in 1 milligram after 1L of filtered water has evaporated.

Let’s take an example. Suppose that we have water, a cup, and sugar here. Why don’t we fill the cup with 1L of water and put 0.5g of sugar? After evaporation, the amount of sugar would be 0.5g. At this time, TDS is 500mg/L (ppm).

Then, I want to talk about the TDS and safeness of various kinds of water that we can see around us. The standard for water quality of drinking water is set below TDS 500mg/L (ppm), and WHO does not provide a precise numerical value.

When we boil groundwater from the European region, limestone is left. It is hard for Koreans to understand this situation. How could Europeans drink water containing limestone? However, Europeans are very healthy and drink water without any doubts. Why is that? That’s because they have drunken this water for several hundreds and thousands of years. So they even get ill from low TDS water while high TDS spring water is more popular. Water bottles have labels indicating a TDS figure.

TDS of bottled water from the Alps is more than 300ppm. However, that of bottled water in Korea is only 30ppm. Korea is famous for clean water and good mountains. It is rare to find a country whose water is as clean as that of Korea.

Then, would you like to guess Korea’s TDS of tap water? The spot from which we get water is different but it is usually 50-250ppm. You may be confused about this fact because this figure of Korea is similar with that of European countries. That’s because chemicals used in the process of purifying tap water dissolves into the water.

How about the water from the water purifier attached to the faucet? Some water purifiers have TDS and some removes it but their TDS figures are not really different from those of tap water.

Of course if we examine TDS where the tap water starts, we can get much lower TDS value. Also, if we compare the upper region of the river with the lower one, it would be obvious that TDS of the lower region is higher than the upper one. The lower region of the river has more pollutants than the upper region, so the valley water in a mountain of the upper region will have far less TDS values. Rainwater will encounter many substances from here and there as it runs down the mountain but there are few foreign substances flowing from nature. Therefore, it is natural that TDS of rainwater before rainwater falls on the ground is lowest.

Definitely, it is possible that pollutants such as sulfur or nitrogen oxide from the air dissolves into the rain. There is dust or yellow dust from air pollution, but it is easy to get rid of them. Some substances that were not filtered exist but its amount is very low. Their TDS is 10-20ppm.

However, there is water that has lower TDS than this. That is the rainwater that the pollutants in it are washed away after rain. Within 20 minutes of pouring rain, pollutants in rainwater are washed away. So the rainwater after 20 minutes is like distilled water. If we want to use this water, it is important to keep catchment area clean. Even though the mud is mixed with rainwater, don’t worry. The remaining particles will be removed if it is carefully deposited and separated from the rainwater. Precipitation is a separating work using gravity, it wouldn’t cost at all. If we screen the sun and carefully pay attention to the water storage system, the water can be saved 5-6 months. In this way, people in regions far from a city have used rainwater. Of course there was nothing to worry. Thus, you can definitely use rainwater.

Now it is time for the queen who cares so much about safety to get an answer from the mirror like “Queen! The purest water in the world is rainwater!” The rain treats the rich and the poor without distinction. However, people think they cannot get the special water because they are not rich like a queen. They just don’t recognize the fact that a queen’s mineral water from the sky comes to anyone for free. How pitiful the sky is! However, the sky doesn’t care and gives us precious rainwater.

Air pollution=Water pollution?

As the mirror taught, a servant brings rainwater to the queen, but is it possible for her to stop her pickiness? She would complain again like “I know rainwater is really clean and safe. I understand that the acidity of the rainwater is not dangerous enough to worry. However, even though rainwater is clean, it will be dirty soon because of air pollution!”

Most of people will also be picky about this issue because of yellow dust rain as well as acid rain. In fact, we can’t find the meaning of “yellow dust rain” from a dictionary. We just call the rain accompanied by yellow dust yellow dust rain. If so, the rain in a coal-mining area will be “Coal rain,” and the rain in the industrial complex should be “Chemical rain.”

Our misunderstanding mentioned above begins with the lack of knowledge about the difference between air pollution and water pollution. It is not true that some substances exposed to the polluted air are dangerous in regard with water pollution. It is not different from the thought that the person who has dark skin would have a dark mind. In other words, pollutants in the air do not contaminate the surrounding water. Some substances affecting our respiratory tract come into the nose, and the membrane in our nose is relatively weak. However, since drinking water is supplied to people after water treatment, there is a huge gap between air pollution and water pollution.

Let’s take an example. When you are in your room, suppose that your mother put some hot pepper powder into the plate to make Kimchi, which is one of the Korean traditional foods. At this moment, you will sneeze even to a little bit of hot pepper flying around. However, that amount of hot pepper powder mixed with water will have no flavor and no effect on our body.

The same principle is applied to the relationship between air pollution and water pollution. The unit indicating the level of air pollution and water pollution will help you understand. The unit of atmosphere environmental standard is microgram/m3 and that of water quality standard is mg/L, and so 1000 microgram=1mg and 1m3=1000L. Do you understand what I said? Is it still difficult? That is to say, for the same substances, they are not a problem in the water quality standard until the level of air pollution exceeds million times of the standard. Even though air pollution is severe, water quality standard never reach million times of the standard in reality.

Someone may ask me again like “On the day of severe yellow dust, car windows are covered with dust. It doesn’t make sense that this is not related to water pollution.” As I pointed out earlier though, yellow dusts are a kind of particle and so they are easily separated after naturally sinking in the water naturally. Evidence that yellow dusts are easily separated from water is yellow dust left on the surface of a car. Also, when an emergency warning of yellow dust is issued, the unit for concentration of a particle is microgram/m3, so it is not a problem in the point of the water standard for safety. Even without this kind of unit system, just think about muddy water that overflows in summer. Since the water facilities of Korea is quite nice, muddy water is handled and supplied to us in spite of its great amount over million to ten million times of yellow dust.

Among air pollution substances, the standard of Sulfide and Nitride is far smaller than that of water pollution. In the standard of water pollution, there are no defined substances but it uses Total Dissolved Substance, the sum of a negative ion and a positive ion. In this case, the standard value of TDS is 500mg/L and it uses far big value exceeding million-ten million times of the standard of air pollution. In the matter of the effect of inorganic substance on our body or recommended amount, experts in WHO reviewed and set the water pollution standard of drinking water.

Of course, before figuring out the effect of air pollution substances on water quality, firstly we should reduce materials that cause air pollution and try to meet the safety standards. However, as I mentioned enough earlier, the reason we have to do so is not because rainwater is polluted, but because we should prevent corrosion of buildings and respiratory diseases.

Can we relieve the queen’s worry now? Are your concerns washed away now? If someone still has doubts, and asks me questions again, there is nothing I can do. If you keep reading this book though, your anxieties will gradually disappear.

The source of rainwater pollution does not exist

Suppose that one company is criticized because of its corruption and tax evasion. This kind of things frequently happens. If all the media and press write articles about this company and make the headlines like “This Company is the core of corruption,” how would the workers of the company feel? It is unfair that they seem to have problems only because they are the members of that company. They would have worked hard every day without knowing much about the company’s corruption only to feel shame in their jobs in a single day.

The reason that I chose this story as an example is to appeal for rainwater’s standpoint to you. Several years ago, the Environment Department coined the word “The source of rainwater pollution,” which does not exist everywhere in the world. They might have tried to express “Nonpoint Source.” When pollutants from a road or farmland are washed and flows into the river, the water from this process is called Nonpoint Source. The Department of the Environment insisted that the quality of the river could be improved with a great amount of money to prevent Nonpoint Source. Although they may have tried to improve the quality of water by managing rainwater, the quality of water has not been improved despite trillions of investment for several years and thus blamed rainwater for water pollution.

Anyways, their purpose should have been improving the quality of water but word choice seems like a problem. What comes into your mind when you hear the source of rainwater pollution? You will immediately think that rainwater equals the source of pollution. Ministry of Environment might claim that it is apparent that the source of pollution caused by pollutants mixed in rainwater is the source of rainwater pollution. However, when we make this word and introduce it, more precise research and realization should be preceded.

During a year, the amount of rainwater in Korea is around 129 billion tons. Then, how much would be the amount of pollutants mixed with rainwater on the ground? Even though we suppose that the amount is 130,000 tons, it is just 1/1,000,000 of rainwater. It is an inappropriate idea that the whole rainwater is the source of pollution because of this small amount of pollutants.

If you worry about Nonpoint Source, cleaning roads or substances that are the source of pollutants in advance can solve this matter. As a stitch in time saves nine, using such an easy way instead of using highly expensive rainwater management method can prevent the water problem in advance.

Another word among several terms that the government uses about rainwater is “Rainwater Reuse.” It doesn’t make sense. Wastewater Reuse is reasonable to use because we can take wastewater again after handling dirty water. Rainwater and wastewater is fundamentally the same but the difference of water quality is huge. Rainwater is clean at first but it becomes wastewater after falling on the ground and mixed with pollutants. So we can reuse wastewater after going through the purifying process, but rainwater can’t be reused because it is clean from the beginning.

Due to the stereotype of rainwater, our precious organic water resource becomes dirty wastewater. Also, it gives rise to all water problems such as lack of water, flood, water pollution, and energy overuse.

Using rainwater is to use rainwater before it gets dirty, and reusing rainwater is to use dirty rainwater after the purifying process. It is almost free and sometimes it doesn’t cost at all for using clean rainwater because we don’t need to do water treatment. However, it costs a lot when we try to reuse rainwater. Why do they want to ‘reuse’ it? Don’t they know that rainwater is clean? They might know it but try to supply the purified rainwater at a high price by building a huge facility. The decision is yours.