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There has been a misconception that rainwater is the cleanest and safest to drink. But you will be surprised to learn that that may not be the case. According to various studies conducted on this water, it has been proven that it can be as polluted as any other water. So, it is not safe to drink rainwater directly. 

Unlike some decades ago, today we have one of the most polluted atmospheres. There are so many harmful and acidic gases in the air that end up contaminating rainwater. In addition, rainwater harvesting methods are also contributing to the contamination. So, is rainwater clean and safe to drink? Well, the answer is no. We have provided 7 major reasons why rainwater is not clean and safe to drink: 

Acidic Rain 

One of the potential contaminants of rainwater is acids. There are many acidic gases in the air, which combines with rainwater to create acidic rain. Some of the common acidic gases include sulphur dioxide and nitrogen oxides. They are produced by factories and the burning of fossil fuels. So, if you are leaving near an industrial area, you might be harvesting acidic rains because of the acidic gases in your atmosphere. That makes your rainwater unsafe for drinking.  

That simply means that you might have a clean and well-kept water harvesting system, but the collected water is acidic. In some cases, acidic rain may reach a pH of 2, although the most common is 4. Whichever the case, the water is too acidic and cause serious health complications. That is one of the reasons why rainwater may not be clean and safe for drinking. 


When dust particles are picked by wind, they become part of the atmosphere. So, when the water vapour starts condensing, or it starts raining, it collects these particles. The dust and dirt particles could be carrying anything from germs to deadly contaminants such as heavy metals to diseases causing microorganisms. Germs and bacteria are the most common microorganisms in the dust. Therefore, the water might appear clean but highly contaminated. That makes it not safe for direct human consumption. Therefore, you will need to have the water filtered or treated to remove the contaminants before drinking.  That is why investing in a water filter is highly recommended. 

Smoke and Pollen 

For the water to be clean and safe for drinking, it must be free of any form of foreign particles or contaminants. But it’s very difficult to find rain that offers meets these standards. Smoke and pollen are some of the common foreign particles in rainwater. If there are areas that are producing smoke such as factories or burning forests, then these particles will be captured and brought back to the ground by rainwater. Some of the smokes could be carrying harmful gases that can harm your health. Therefore, such water should be treated before drinking. Otherwise, you might end up consuming harmful chemicals. 

woman in the rain

Roof Contaminants 

The condition of the roof that’s collecting rainwater is another factor to consider. When the rain washes across the roof, it collects everything including germs, dust and chemicals attached to it. That’s how the harvested rainwater becomes unsafe. Additionally, construction materials such as asbestos and asphalt, which are petroleum products, and metals such as lead and copper on the roof can also contaminate water. All these contaminants will find their way into your water storage. Unless this water is filtered before use, it is not safe for drinking. You should also consider cleaning your roof before rains start. 

Bacteria and Virus In Rainwater 

Contrary to what some people think, there could be many bacteria and viruses in the rainwater. Most of these bacteria are collected on the roof and gutters. However, there are airborne bacteria in the atmosphere which finds their back to the ground through the rain. For the roofs, most of the bacteria are in the dust particle as well as from the bird droppings. Small animals that can climb up the roof, such as cats can also spread bacteria. In addition to that, bacteria could also be coming from decomposing organic matter such as plants and dead animals in the storage. All these types of bacteria and viruses make rainwater unsafe for drinking. 

Contaminated Storage 

One of the biggest mistakes that people make is poor storage for the harvested rainwater. If you have done everything right up to the storage, then you need to keep this water in the tank for a very short time. The longest you can have it in the tank is ten days after harvesting. If it goes beyond ten days, then you will have a problem of contamination. The most common contamination is mosquito larvae contamination. You should also install screens to prevent debris and animal contamination such as bird dropping entering the storage. 


As the rainwater washes over the roof and gutters, it collects a lot of dust and dirt which forms sediment and slime at the bottom of the tank. If the water stays in the storage tank for long, the sediment accumulating at the bottom will start decaying. That’s when you will start experiencing some unpleasant smell and sometimes tastes coming from the water. The unpleasant odour will get stronger as the time goes as well as the water level lowers due to higher concentration. In such cases, then the water will not be safe for drinking. 


Rainwater may look clean, but it can be heavily contaminated. There are a lot of contaminants in the atmosphere and throughout the rainwater collection system, which makes it unsafe for drinking. From germs, dust particles, bacteria, virus and parasitic microorganisms, there are many contaminants that can cause serious health complication. So, you need to treated or filter your rainwater before drinking to make clean and safe.