Solutions for Self-Reliance

Rainwater Harvesting: Why Everyone Should Care and How to Do It


Don’t like rain? Don’t be so quick to reject the water falling from the sky. In ancient times rain was seen as a blessing by many peoples, and for good reason. Here’s why everyone should care, and how you can start collecting rainwater from your own roof.

And you can catch a lot of water from a roof. The roof of a 1,000-square-foot house can collect around 600 gallons per one inch of rain – that’s enough free water to fill more than 15 bathtubs!

(Want to learn about the 3 tactics to create water abundance for your home and garden? Click to grab The 3 Best Tactics to Create Water Abundance)

First; is it Legal to Harvest Rainwater?

In most US states rainwater harvesting is actually encouraged, but not all states are alike. Most notably, in Colorado it is still illegal to collect rainwater that falls on your property because the state of Colorado claims the right to all moisture in the atmosphere that falls within its borders and that “said moisture is declared to be the property of the people of this state, dedicated to their use pursuant” to the Colorado constitution.

Personally I think that’s crazy and a clear violation of the natural rights of man, but I’d still advise you to check your local and state laws before starting a project like this.

With that said, let’s jump into the fun stuff!

What Is Rainwater Harvesting?

As the name implies, it’s all about collecting the rain that falls on your roof or on your land and diverting it into storage tanks. The water can then be used for any purpose such as watering your garden and, with treatment, can be consumed safely.

A basic rainwater harvesting system consists of:

  • A catchment area (for example a roof)
  • A conveyance system (for example rain gutters and a downspout with a debris filter)
  • A storage system (for example a simple barrel, an underground tank, or a pond)

It doesn’t have to get more complicated than that.

Why would you want to do this when you’ve got unlimited water coming from your tap?

Because rainwater harvesting is a key to decentralizing the water supply, thus removing your reliance on a community water supply that can be cut off or contaminated in emergencies.

From depleting aquifers and burst water pipes to Cryptosporidium and other drinking water contaminants, there are many things that can disrupt your water supply. By collecting some or all of your water yourself, you remove many of these risks.

Plus, why pay for water when nature provides it for free? That’s the biggest benefit in my mind. It’s an affront to nature (and to yourself!) to let clean rainwater wash away into the sewers while you pay good money for chemically treated tap water from a fragile water infrastructure. Money that could be used to get debt-free or to save up for “rainy days”.

Rainwater collection systems can range from simple, like catching the water off your roof in open barrels or ponds, to complex, like burying an underground tank and integrating it into a building’s plumbing.

A Rainwater Harvesting Case Study:

I am installing a rain harvesting system on my barn and a small system to top off the pool. The goal is to develop a standalone potable water system that uses many levels of particle filtration, multiple storage tanks, and pumping using a solar booster pump, charcoal filter for taste and UV for treatment.

Scott Hunt, engineer775 on Youtube.

To get the full rundown of what rainwater harvesting is about, check out this infographic:

Why Everyone Should Care About Rainwater Harvesting (and How to Do It)Infographic by CustomMade

Rainwater Harvesting Formula (via grow NYC)
How To Calculate How Much Rainwater You Can Collect

In order to figure out the size of the tank you will need to store the rainfall collected in your rainwater harvesting system, it is important to know how large the roof is. Most rain events are 1 inch or less.


  1. Measure the length and the width of the roof but check where the downspouts are to find what part
    of the roof drains to each downspout when there is more than one downspout. For example, if the roof
    is pitched in 2 directions and you are only able to use the downspout on one side then just measure the
    part of the roof that drains to the downspout you will use.
  2. Every square foot of roof space collects .6 gallons of water in a 1 inch rainfall.
  3. To account for losses and inefficiency, you can expect to collect about 75% of the actual rainfall so
    your calculation should be multiplied by .75


Length of roof ____________ feet
X width of roof ___________ feet
X .6 gallons per square ft
X .75
X __________________ inches of rainfall
= _______________________ gallons of rainfall collected

Sources: grow NYC & Custom Made

(Want to learn about the 3 tactics to create water abundance for your home and garden? Click to grab The 3 Best Tactics to Create Water Abundance)

Get this free guide

Liked this post? Share it with your friends to keep the sustainable revolution moving forward!

Like it? Show your support on Patreon! Let us change the world.
Become a patron at Patreon!



Suggested Videos

Self-Reliance is Hard
We Make It Easier

Solutions for Smarter Self-Reliance:

You'll find them in The Self-Reliance Catalog; a carefully curated collection of the best plants, tools, shelters and systems for self-reliance and resilience.

Free Registration