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Rainwater harvesting is an excellent way to conserve water, gain some independence from municipal water supplies and to save money in the process. However, is it safe to drink? Rainwater has been drunk since ancient times and is considered one of the purest forms of water. However, during the journey from rooftop to glass, rainwater can collect a wide range of contaminants.
Here’s what could be in your rainwater and how to make it safe to drink.
Potential Contaminants in Rainwater
Because rain passes through the atmosphere on its journey towards earth, it can collect contaminants found in air. Air pollution is an increasing issue in the world, especially in industrial cities and around radioactive sites, meaning that rain falling in these parts of the world will most likely contain a large number of contaminants.
Additionally, you might think that rainwater falling off your roof is pure, but there could be any number and type of contaminants on your roof. These could include bird poop, leaves, twigs, insects and fungi. The roofing material could leak lead, asbestos and iron you’re your water. Drinking this is a recipe for disaster and can easily cause diseases.
In short, while rainwater is one of the purest types of water, it is only as clean as what it encounters. This means that whether or not you get sick from rainwater depends on the location the water is sourced from.
To learn about the different types of contaminants in water, check our article.
Is Acid Rain Dangerous?
Acid rain is rain with a low pH, typically around 5.0 to 5.5. This happens when rainwater reacts with carbon dioxide, which lowers the pH of the water. While the name acid rain sounds frightening, this type of rainwater is safe to consume.
While we tend to think of drinking water as having a neutral pH of 7, this is not often the case. The many additives in water, including mineral compounds and salts for example, can make the pH fluctuate. Carbonated water is very popular today and it has a pH that’s lower than acid rain, at typically 4.5.
The problem with acid rain, then, is not its acidity but the potential contaminants that could be in it.
How to Treat Rainwater
When you collect rainwater, you would need to treat the water to ensure it’s safe to use. However, using a single treatment method wouldn’t ensure that the water is safe. For example, here’s a look at the most popular ways to purify water and the issues they pose:
- Chlorine Disinfection – If you decide to use chlorine to purify your water, you’d mainly be targeting biological contaminants, while physical and chemical contaminants would still remain in the water.
- UV Lighting and Boiling – This system removes microorganisms by attacking their genetic code, but it doesn’t filter the water.
- Filtration – Using some form of filtration, like activated carbon block, will remove a large number of contaminants, but not all. Microorganisms can get through and so can many smaller dissolved particles.
- Reverse Osmosis – This removes most of the contaminants in your water but may let microorganisms through.
- Distillation – Distilling your water gives you one of the purest types of water, but some contaminants, like VOCs, can get through.
So, what does this signify?
To ensure that your rainwater is safe to consume, you would need to treat it with a combination of methods to remove the highest number of contaminants.
First, it’s a good idea to test your rainwater to know what types of impurities it contains. Next, select a filtration system that will effectively remove these. If you aren’t sure what type of filter to use, we cover this here in our step by step guide on how to choose a filter for your home.
Filtering rainwater using an effective filtration system and then using either reverse osmosis, boiling or distillation on the water, can make your rainwater safe to drink.
What Are the Pros and Cons of Drinking Rainwater?
With all that said, here’s a quick look at the advantages and disadvantages of drinking rainwater.
Advantages:
- Rainwater doesn’t contain a lot of chemicals that are routinely added to municipal water supplies. This includes chlorine, chloramines and fluoride. While these chemicals are highly regulated and monitored in water supply, they can cause health issues and impact the taste and smell of water.
- Rainwater is free to collect and use, as long as your state allows it.
- Rainwater from pure, clean regions can have a fresh, crisp taste.
Disadvantages:
- The quality and availability of your rainwater depends on where you live. If you live in a dry area which sees little rainfall, then harvesting rainwater may not be a viable option for you.
- Rainwater is slightly acidic as it doesn’t have the natural minerals to balance its pH that groundwater has. As groundwater percolates through the soil, it acquires minerals that give it its ‘hard’ nature and makes it alkaline. Because rainwater has few or none of these nutrients, its ‘soft’ water that’s slightly acidic.
- If you have a weak immune system, it’s best to discuss with your healthcare provider before you decide to drink rainwater. You may need to filter and/or distil the rainwater to make it suitable to drink.
The Bottom Line
So, to answer the question – is rainwater safe to drink?
- Yes – You’ve filtered and disinfected it, effectively removing contaminants
- No – The rainwater hasn’t been treated and is only as clean as everything its come into contact with
- Maybe – Rainwater can be cleaner than the municipal water supply depending on the location you live – like in a rainforest where rainwater is unlikely to have contaminants. Even so, we would recommend testing and purifying.
Rainwater is an excellent source of water, and while it’s typically used for tasks like watering the garden and lawn, washing the dogs, washing the car and flushing toilets, it’s also great for drinking as long as you purify it.
When purifying your rainwater, opt for a combination of methods as no single water purification method can target all contaminants. At the end of the day, all supplies of water, whether municipal, well or rain, comes with common contaminants. You can decide what water quality you want to drink by treating it effectively.
Learn more about rainwater harvesting systems here.
