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Every drop of water you’ve ever drunk, swam in, bathed in, or watered your plants with was once a drop of rain falling from a cloud. Of course, those drops of water were probably purified at your local water treatment plant.
But what if the treatment plant shuts down due to a major disaster? Is it safe to harvest rainwater and drink it?
The answer is yes, but you have to do it right.
Instead of placing a thousand basins out in a rainstorm, you should build your very own rainwater harvesting system. This system collects rain and stores it safely for you to drink at your convenience. For sustainability and economic purposes, harvesting rainwater is an ability any long-term prepper should have.
However, there are more considerations than you might expect. Here is everything you need to know about harvesting potable rainwater.
1. Determine if Collecting Rainwater is For You.
Most people don’t realize that naturally collected rainwater is not as pure as it looks. Sure, it falls from the sky into whatever contraption you use to collect it, but contaminants and germs are collected as well.
This is something that even I also had a problem coming in terms with; I literally spent the whole of my childhood life praising and drinking rainwater directly.
This is especially true if the water is pouring off of some other surface before filling up your container. Roofs have many things sitting on their surfaces that are not safe to drink, such as animal fecal matter.
Some Roofs May Have Traces Of Chemicals Or Other Poisonous.
You must also be aware that some roofs may have traces of chemicals or other poisonous substances such as chrysotile on them, so any water collected from the roof is most likely contaminated.
And if you live in Nairobi, Mombasa, and other highly-populated, or even near one, your rainwater may become contaminated before it has the opportunity to hit any surface. This is due to the pollution in the air. In some cases, environmental pollutants can be dissolved into the rainwater as it’s falling. So as you can see, there are many ways for naturally collected rainwater to become contaminated, and it surely will be unless preventative measures are taken.
Although treating water with iodine can be safely done when you’re camping, it is not the best treatment for rainwater. Iodine does not treat or make your collected rainwater safe for consumption if the water has been contaminated with chemicals. You will also want to make sure your collected water doesn’t remain standing long enough for mosquitos to turn it into a breeding ground.
All this is why I recommend you use collected rainwater for purposes other than consumption, such as watering your garden, washing, or flushing your toilet. I also don’t recommend rainwater if you’re ill or have a weak immune system. If your main purpose for collecting rainwater is to drink it, then you should either boil it first or use a good water filtration system.
2. Calculate Your Water Requirements.
Once you’ve decided harvesting rainwater is for you, you’ll need to figure out how much water you and your family will need.
3. Determine how you will use rainwater.
Are you hoping to completely sustain yourself on rainwater? Are you wanting to irrigate and supply water for homestead animals as well? Or are you merely providing a supplemental supply in case of emergencies? Your answers will determine how much water storage you’ll need.
4. Learn How a Water Harvester Works.
The principles of a rainwater harvester are fairly simple. Rain falls onto some sort of roof, which guides the water into a storage container. However, doing so in an efficient and sanitary way takes a little ingenuity.
You will need 7 basic components to harvest rainwater:
The catchment surface refers to the roof which will collect rainwater. Generally, the bigger the better, as more square footage will allow you to store more rainwater. The catchment surface is one of the most important parts of harvesting rainwater.
Roof-Washing and First Flush System.
Since your catchment surface will be exposed to the elements, it will surely become dirty. Just as you need to wash your car now and then, your roof needs a good cleaning, too. Fortunately, you can let Mother Nature do the job for you with a roof-washing and first flush system. This essentially collects the first few inches of rain and discards it in a flush system, removing debris naturally at the beginning of every rain.
- Storage Tanks.
Obviously, you will need one or more storage tanks to store your water. It is also your primary concern when it comes to keeping your system sanitary since it will be where water can stagnate.
- Conveyance System.
The conveyance system is what connects the catchment surface to your storage tanks. This system might be as simple as a gutter leading from your roof to your tank, but if you have multiple tanks, multiple catchment surfaces, or underground storage, the system can get a little more complicated.
- Screening Mechanism.
This essential part can be over the catchment surface, the storage tanks, or both. You will need some sort of screen to keep objects off your roof and out of your stored water. Contaminants like dirt and organic matter can build up on the roof, leaching harmful chemicals into your water. Similarly, they can permeate your water storage and cause disease.
- Water Filtration and Treatment.
You can store as much rainwater as you like, but it will eventually become contaminated without proper filtration and treatment. There are many types of filtration and treatment discussed in the next section.
- Delivery System.
The delivery system is responsible for getting the water out of storage tanks and into your glass. Some areas simple as gravity-fed taps, while others involve pressurized pumps and complicated piping.
5. Acquiring and Combining the Right Supplies.
Now that you have a basic understanding of harvesting rainwater, it’s time to combine the parts into a whole. There are many ways to do each step; simply choose the best fit for your needs. If you have trouble with any of the steps, see what each component looks like in this video:
- Build The Catchment Surface.
This is your first step. Your roof should catch rainwater and slope it in an intentional direction. The best materials are roofing materials such as corrugated sheets, box profiles, and other slick surfaces. Stone, concrete, and clay roofs will work as well, but you may lose water that soaks in. Wood shingles and asphalt shingles are not ideal, as rainwater will absorb toxins from these materials.
- Build a Conveyance System with a First Flush System.
Determine how you will transport your water collected by the catchment surface. Your best bet is simple PVC piping that uses gravity.
- Set Up Your Storage Tanks.
Run the conveyance system into your storage tanks, which you can place either above ground or underground. There are many different types of tanks you can buy.
- Screen Your Tank and Catchment Surface.
Any type of screen will do to protect your system from small bits of organic matter like leaves. Also, consider building your system far enough away from trees that nothing will fall onto it.
- Set Up Your Water Filter and Treatment System.
There are various ways and products for water filtration and treatment. The first and easiest is to add chlorine bleach to your supply.
- Hook Up Your Delivery System.
Once all the other components are in place, set up your delivery system. There is a multitude of options available, from gravity-fed nozzles to hand pumps to complicated electric systems.
With a little bit of ingenuity and enough attention to detail to prevent disease, you can have a sustainable water source for a lifetime by building a rainwater harvesting system. Creating your own is not as difficult as it sounds or seems initially—after all, you most likely already have the roof of your house to use as a catchment surface.
Your ancestors have been doing it for thousands of years, and today, we know more than ever about how to make water safe. We also have more materials available than ever, which is why you should start planning your very own rainwater harvesting system today.