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Rain Collection: How Using a Rainwater Collection System Can Help You Survive

There are many ways to prepare for a disaster. But for most of us, preparing for an emergency or natural disaster involves preparing drinking water for when the municipal water source becomes unreliable and survival food buckets for when food shortages strike our grocery stores.

What if we suggested that you didn’t need to purchase hundreds of water bottles or draw endless gallons of water from the tap? What if, instead, we suggested there is a way to implement a rainwater catchment to fill your water storage containers free of charge?

Keep reading to learn more about the history of rainwater collection and modern rainwater collection systems and their importance it using water off grid. The rainwater you collect now could mean the difference if sh*t hits the fan (SHTF) later on.  

Download our free emergency preparedness checklist and learn how a rainwater collection system can help you survive during a power outage or other emergency. 

What Is a DIY Rainwater Collection System? 

rainwater collection

Rainwater collection, also known as rainwater harvesting, is accumulating, storing, and reusing natural rain precipitation that falls from the sky during storms.Humans have collected rainwater since antiquity.

Back then, rainwater cisterns were a necessity, especially in arid environments like the Middle East and Ancient Rome. In ancient civilizations, rainwater cisterns were common in most homes.Survival Community cisterns were also prevalent and could store upwards of 11,000,000 gallons of water!

Since then, diy water catchment systems have greatly improved. Simply put, a rainwater collection system involves just a few essential parts. First, rainwater harvesting requires a catchment surface. Nowadays, this is the roof of your house. This inlet is typically covered with a screen to filter out debris and keep out insects.

The next necessity in the process is storage containers or rain collection barrels to hold the freshly harvested water. Collection tanks should be made of BPA-free and non-transparent material. The reason is that if sunlight is not blocked, algae may form and ruin your water supply.

Then, to transport and use the collected rainwater, the collection system uses an outlet, such as a spigot, pipes, and hoses to move the water and use it for various important tasks.

Besides the initial costs of installing a DIY rainwater collection system, there are few drawbacks to collecting rainwater. Instead, collecting rainwater mostly only offers benefits that improve your already self-reliant nature.

New DIY systems include first flush devices and diverters. A first flush device, also known as a roof washer, helps in collecting the first few gallons of rainwater which may contain contaminants from the roof. This water is discarded, and the rest is directed to the storage tank. It ensures the water entering your storage tank is clean and less likely to contain contaminants.

Benefits of DIY Rain Collection System


rainwater collection benefits


People collect rainwater for all sorts of reasons, the major one being that collecting rainwater gives you a free water source. Free water and lower monthly water bills are hard to beat, but it’s not the only benefit of rain collection.


  • Rainwater is an ideal backup source of water in case of emergency.

  • Collecting rainwater reduces storm water runoff from your home and therefore solves drainage problems on your property.

  • Rainwater can irrigate the landscape around your home, specifically your small home garden.
  • Rainwater collectors promote self-sufficiency and help conserve water.

  • Collecting rainwater keeps you in charge of your water supply, despite living in areas with water restrictions.

  • Compared to some municipal waters, rainwater is a relatively clean and healthy water source, especially if you got a good place to live off grid.

  • Most rainwater collector systems are modular, meaning that the system can be expanded, reconfigured, and relocated if necessary.

  • Most rainwater collectors can be retrofitted to existing and older structures or be built onto new buildings during the construction process.

It's important to note that collected rainwater can be used for more than just human consumption. It can also be used for livestock watering and for aquaponics systems, where the nutrient-rich water can feed plants.

Uses For a DIY Rainwater Collection System

After a good storm and your rain collection barrels are all filled up, it’s time to put your freshly harvested rainwater to use. You may also choose to save it for later and move it into water storage containers. Whatever the case, there are three main categories where collected rainwater can be utilized.

  1. Irrigation for your prepper garden
  2. Indoor or outdoor non-potable usage
  3. Indoor potable usage

Irrigation with DIY Rainwater Collection


rain collection irrigation


One of the simplest ways to use harvested rainwater is to connect a hose directly to the rain catcher and use the water to irrigate your property. For example, you can hand water your lawn or the fruits and vegetables in your garden. You may even consider hooking your rainwater collection system to your sprinkler system.

Non-Potable Usage with Rain Collection Systems


non potable rainwater collection system


Collected rainwater can be an essential source of non-potable water. When enough rainwater is harvested, it can replace the tap water you’re used to using for non-potable usages. For example, you can use rainwater for indoor, non-potable fixtures, such as toilets and clothes washes. 

You can also use the rainwater to wash your vehicles, refill your pool or hot tub, top off your fountains or fish ponds, bathe your pets, or wash off your driveway and sidewalks.

Potable Usage with DIY Rainwater Collection Systems

Harvested rainwater does not only have to be used for non-potable uses. You can also filter and treat your collected rainwater with water purification tablets to make the water potable and safe to drink. Once you have treated the water, it can also be used to prepare and cook food. 

In addition, when rainwater is appropriately filtered and treated,  you can prep the water for long-term water storage. Then, if SHTF, and the municipal water source in your area becomes unreliable, you will still be able to survive.

Is a Rain Collection System DIY Illegal?

Before you start designing a DIY rainwater harvesting system, it’s important to make sure that collecting rainwater in your area is legal.

By and large, rain collection is a legal activity. The federal government does not have any laws that restrict harvesting rainwater. In addition, most individual states allow their residents to collect rainwater freely. Some states, such as Rhode Island, Virginia, and Texas, even encourage residents to harvest rainwater by offering tax credits or exemptions on equipment purchased and utilized for harvesting rainwater. 

However, it wasn’t always that way. In some Western states, there are restrictions on collecting rainwater. These restrictions are the result of old legislation that made collecting rainwater illegal. Back then, “prior appropriation” or “first come, first serve” water laws stated that all precipitation belonged to the existing water-rights owners of the local area. 

Rainwater restrictions are present in some states because it is thought that collecting rainwater will negatively affect the earth's natural hydrological process. However, very little research has shown that to be true—especially considering that the collected rainwater eventually returns to the earth after it is used for irrigation or other purposes.

Maintaining Your DIY Rainwater Collection System

Proper maintenance of your rainwater collection system is crucial for ensuring a continuous supply of clean water. Regularly inspect your catchment surface, gutters, and downspouts for debris, and clean them as needed. Check your storage tanks for leaks and algae growth, and make sure the screens covering the inlets are intact and clean.

Choosing the Right Size for Your DIY Rainwater Collection System

To determine the size of your rainwater collection system, you need to consider your catchment area, average annual rainfall, and your water usage. Calculate the catchment area by measuring the square footage of your roof or other surface you plan to use for collecting rainwater. Then, research the average annual rainfall for your location. Multiply the catchment area by the average annual rainfall, and divide by 12 to get an estimate of the monthly rainwater yield.

Next, estimate your monthly water usage for the activities you plan to use the collected rainwater for, such as irrigation, non-potable uses, or potable uses after filtration and treatment. Compare the monthly rainwater yield and your estimated water usage to determine the size of your storage tanks. Make sure to choose a system that can accommodate your water needs during the dry months, when rainfall might be scarce.

To determine the size of your rainwater collection system, about emergency preparedness, and whether you should bug out vs. bug in, or how much food to store in case of natural disaster, please visit our Valley Food Storage website. Our Practical Prepper Blog is a massive source of helpful information. And as always, if you would like to schedule an appointment with one of our product experts, visit our website.

Considerations Before Installing Your Rainwater Collection System

Before you jump down the rabbit hole and begin purchasing equipment and installing a rainwater collection system, we recommend you consider the following items.

  1. Roofing Material
  2. Gutter Type
  3. Tank Size

Understanding the DIY Water Catchment System


rain collection roofing


When it comes to collecting rainwater, not all roofs are considered equal. In fact, there are some roofing materials that are much better off for collecting rainwater than others. 

The best roofs for collecting rainwater are made of terracotta, concrete tiles, factory-coated enameled steel, glazed slate, or zinc-coated galvanized metal. 

When it comes to roofing materials, you want to avoid asphalt and fiberglass shingles. These materials are coated in antifungal chemicals. Chemicals and other toxins can also be found in cedar shingles, Bitumen and composite roofing.

 [product_render product-handle="entree-bucket"]

The next necessity in the process is storage containers or rain collection barrels to hold the freshly harvested water.

Gutter Type

The best gutters for rainwater collection are coated aluminum or vinyl. Galvanized steel gutters are good as well, but only if you plan to use your rainwater for non-potable usages. 

For rainwater collection, you want to avoid gutters that are constructed with copper or lead materials.  

Ideally, your rain gutters will be 5 inches wide and installed with a minimum 1/16” slope per foot.  

Tank Size

Selecting the correct sized tank for your rainwater collection system is vital. If you go too small, you will fill up too quickly and not collect all the potential rainfall. And if you go too big, then you run the risk of investing too much money and physical space to a collection system that is only operating at half capacity, or less. 

So for tank size, let’s dive into the details a bit more.  

Do you know what you would do if there was no electricity and stayed out for an extended time? Download our free emergency preparedness checklist today!


download our preparedness checklist


What Size Water Tank Is the Best for a Rainwater Collector?


water collection system


The short answer to this question is—it depends. So as you can probably guess, the long answer is a bit more nuanced. 

Figuring out what size water tank is best for you depends on two important things: the intended usage of the collected rainwater, and your local climate. 

Like we talked about above, there are many different ways to use your harvested rainwater. If you plan to use the rainwater for simple tasks, like irrigating the garden and periodically washing the car or your pets, then smaller-sized water tanks will be sufficient.  

However, if you plan to use the collected rainwater to replace the tap water you would ordinarily use for drinking and household tasks, then you should select larger-sized water tanks. 

The local climate where you live will also impact what size water tank is best for you. In areas where there is frequent rainfall, such as the Pacific Northwest, small to medium-sized water tanks are sufficient, because more frequent rainfall will refill the smaller tanks and keep them full.  

On the other hand, if you live in an area that typically only gets rain precipitation for a handful of months out of the year during the rainy season, then we recommend larger rain collection barrels; because if the rain is infrequent, it’s best to take advantage and collect as much as possible in order to last a long time.

Roof Surface Area & The Correct Size Water Tank for DIY Rainwater Collection


rainwater collector plastic tank


Nowadays, we take advantage of the roofs of our homes to collect rainfall. Then, our rain gutters and drains direct the fallen rain into our rain collection barrels. For that reason, it’s important to consider the surface area of your roof when calculating how much rainwater it will collect and when selecting the correct size water tank. 

To put it simply, a storm that drums one inch of rainfall does not mean you will only collect one inch of water in your collection barrels. You will actually collect a lot more than you think! But let’s walk through a hypothetical example to explain this in detail.

  1. In this example, you have a 2,000 square foot house and the approximate size of your roof is 50 feet x 20 feet. 

  2. Your roof has one pitch directly in the center. For that reason, you’ve installed a rain collection barrel on the downspout on one side of your roof so that you can capture all the rain that falls on that side of the roof.

  3. It’s hurricane season and a storm rolls through that records one inch of rainfall.

  4. First, convert 50 feet x 20 feet to inches, thus 600 inches x 240 inches.

  5. Next, multiply the area of your roof in inches by the amount of rainfall, in this case, one inch. 600 inches x 240 inches x 1 inch = 144,000 cubic inches of rain.

  6. Lastly, convert 144,000 cubic inches of rain into gallons by dividing by the amount of cubic inches in a single gallon. So, 144,000 / 231 = roughly 623 gallons of collected rainfall.

From this example, you can see that collecting rainwater adds up extremely fast. In this example, if you only had a small, 55-gallon tank, you would be pretty disappointed by how much rainwater you would miss out on after your tank was overfilled. It would be much better to have a larger, 600-gallon water tank (or larger) to take full advantage of the storm’s rainfall.   

For more details about the rainwater collection potential in your neighborhood, we recommend that you visit the U.S. Climate Atlas.

Conclusion: Rainwater Catchment System DIY

Harvesting rainwater is a fantastic strategy for preparing you and your family for impending water shortages. On average, a home’s roof collects 600 gallons of water per one inch of rainfall. If you invest some time and money in a rainwater collection system today, you will have hundreds, if not thousands of gallons of harvested rainwater at your disposal when SHTF and the municipal water system is no longer reliable. 

When it comes to the feasibility of a DIY rainwater collection system, it's worth noting that it does not require an extensive amount of skill or resources. In fact, many individuals who are interested in self-reliance and sustainability find the construction process of such a system to be a rewarding endeavor in itself. There are numerous guides and tutorials available online that provide step-by-step instructions on how to construct your own rainwater catchment system, making it an accessible project for people of all skill levels. You can also get creative and customize the system to your needs and preferences, and even use it to help humidify your DIY root cellar to help you in storing garden vegetables you've been irrigating.

The quality of collected rainwater is often superior to that of municipal water, as it does not contain the chlorine and other chemicals often found in treated water. However, it's important to note that while rainwater is usually safe for non-potable uses straight from the catchment system, it requires additional treatment if it's to be used for drinking or cooking. Common methods include boiling, chemical treatment, and filtration.

For more information about emergency preparedness, and whether you should bug out vs. bug in, or how much food to store in case of natural disaster, please visit our website. Our Practical Prepper Blog is a massive source of helpful information. And as always, if you would like to schedule an appointment with one of our product experts, visit our website.