If SHTF and your water supply runs dry, knowing how to harvest rainwater can be an invaluable skill. According to the EPA, the average US citizen uses almost 100 gallons of water per day. Even in a survival situation, each person in your household would still need about 2-4 gallons a day for drinking and maintaining proper hygiene.
It’s possible (and a good idea) to store clean water in case of an emergency, but any long-term planning requires a sustainable source of water which you can create by building a system to harvest rainwater.
The Legality of Harvesting Rainwater
It sounds strange, but there are some states with laws against collecting the rainwater that falls on your property. In fact, it was only recently that my state, Colorado, made it legal to harvest rainwater. In Colorado, water is considered the property of those downstream, and some people worry that collecting rainwater before it hits the ground impedes natural water drainage.
Luckily, now people in the state do have the right to harvest this valuable source of water, but there are still laws that dictate how this rainwater can be used. If you do decide to go ahead and start collecting rainwater, check the laws in your area to make sure you are in compliance with all codes and regulations.
Reasons to Collect Rainwater
If harvesting is permitted in your area, then rainwater is a valuable free resource that you and your family can take advantage of. Because it has not yet percolated through the earth, rainwater tends to be free of many of the pollutants found in most underground and surface water sources. This means that for the nominal cost to build a collection system, you can have access to a renewable supply of water that can be used for cooking, landscaping, cleaning, and many other tasks.
A Basic System to Harvest Rainwater
A basic rainwater harvesting system will have three main parts: the catchment area, a means of conveyance, and one or more cisterns. The vast majority of harvesting systems use a roof as the catchment area. This is good news for preppers since chances are your home already comes with a roof you can use for this purpose.
One thing to keep in mind is the fact that you will most likely need to incorporate a roof washer into your system. Various contaminants can settle on your roof and pollute the rainwater you collect if you aren’t careful.
The size of your roof also factors into how much water you can harvest. The equation below can provide a good idea of how much rainwater you can hope to collect based on the square footage of your roof.
Conveyance is simply another term for the gutters and downspouts on a root that will direct rainwater into your storage tanks. Proper installation is critical for gutters and downspouts to ensure that they can function properly without causing any damage or safety issues. If you own an older home, you should double-check that there is no lead present in your gutters before using them to harvest rainwater.
Depending on the intended use of harvested rainwater, your cisterns can wind up being very simple or extremely complex. If your goal is to store rainwater for landscaping purposes, something like a trashcan can be quite effective. A system designed to collect potable water will likely be larger and include some kind of filtration or treatment capability.
Treating Harvested Rainwater Water
There are numerous systems that you can use to treat rainwater and make it potable, but many of these systems are expensive and require a significant amount of energy. While such measures are ideal for producing clean drinking water, I wanted to look for a system that would work under less-than-ideal conditions.
In an emergency, you can integrate your storage tanks with a basic sand and gravel filtration system to produce drinkable water. This is a method that has been around for centuries and remains an effective and cheap way to treat rainwater.
Note: If you’re out and about, using a tool like the LifeStraw Personal Water Filter can help provide you with clean drinking water by filtering out 99.9% of bacteria and parasites from water.
Mistakes to Avoid
Check out the video below to see the top mistakes people make when collecting rainwater and how to avoid them: