Rainwater harvesting — the collection and storage of rain to use as a primary water supply — is one of the simplest and oldest methods of self-water supply.
And it’s still a great one.
Rainwater is the cleanest form of water on the planet.
While you’ll still need to filter it before use, learning how to harvest rainwater has numerous benefits.
In this blog, we’ll tell you everything you need to know about this cheap and sustainable system.
Let’s get started.
1. What is rainwater harvesting (RWH)?
Rainwater harvesting is the collection and storage of rain for use.
RWH often involves harvesting rain from a roof.
As the water is channeled into downspouts, it can be directly transferred into rain barrels or other collection containers.
Rainwater harvesting is a viable alternative for anyone looking to supply their household or business with water.
While it’s traditionally thought of as something that homesteaders do, anyone can use these methods and reap the rewards.
You may also hear it referred to as rainwater collection, rainwater catchment, roof water collection, or rooftop water collection.
RWH is a viable technology in both urban, suburban, and rural settings.
It provides you with the ability to take advantage of a free water source and can be configured to supply your entire house or landscaping needs.
2. Is rainwater clean?
If you’ve never harvested rainwater previously, you may worry if it’s clean.
Is it safe to drink?
Will it make me sick?
The answer all depends on where it’s coming from.
In general, most rainwater is safe as long as you don’t drink it near chemical plants and areas of high pollution.
However, the general recommendation is that you filter it before you drink.
Another way to make the rainwater safer is to boil it to make sure you’re killing off any pollen or bacteria that may be lingering in the water.
Boiling it is a good step if you want to use it for non-consumption purposes, but we still recommend going the extra step of filtration to ensure you have clean water.
3. Is rainwater harvesting legal?
As you begin your research, you may hear some horror stories about people facing legal consequences for harvesting rainwater.
This will leave you with the question: Is it legal?
Yes, it is legal.
There are no federal laws that restrict rainwater harvesting, and while some states have strict regulations, most states will allow their residents to collect rainwater freely.
4. What types of regulations and restrictions do states have?
Some states have regulations about the amount of rainwater one can collect as well as how you can collect it.
That said, most states allow their citizens to collect rainwater freely and even encourage its collection.
The states with regulations believe that the collection of rainwater may halt the rainfall’s natural flow into the Earth’s aquifers and streams.
Thus, it will disrupt the hydrologic cycle.
However, a study published in the Scientific World Journal states that the amount of rainwater collected by individual homes would have little to no impact on the overall hydrological cycle.
As most of the collected rainwater would be used for gardening and household purposes, the water would eventually be returned to the ground.
And then sometimes states also restrict rainwater usage because of old prior appropriation laws.
Today, most states have shifted their laws in favor of private RWH.
Utah and Colorado are the only states with heavy regulation, and Colorado is the strictest of the two.
In 2016, they passed a bill that allows for the collection of rainwater with a 110-gallon maximum capacity.
See the next section for more information about the restrictions and regulations in each state.
So, remember, rainwater is a resource.
Once it falls on your property, it’s generally yours to use without restriction.
Organizations like the American Rainwater Catchment Systems Association (ARCSA) are generally working with government organizations to advocate for rain harvesters all over the country.
5. What is a state-by-state guide to rainwater harvesting?
Are you still worried about the possible restrictions in your state?
If so, we put together a state-by-state guide to help you understand any restrictions or regulations in your local area.
Alabama – No regulations or laws against rainwater harvesting
Alaska – No regulations or laws against rainwater harvesting
Arizona – Regulated through the Department of Water Resources; city or town may provide money to fund rainwater harvesting systems
Arkansas – Regulated through the State Board of Health, which allows a system used for nonpotable water that complies with the Arkansas Plumbing Code and is designed by a professional engineer
California – Regulated through the Division of Water Rights, which includes specific system requirements and licensing criteria that landscapers must follow to install rainwater harvesting systems
Colorado – Each house is allowed a rain barrel of up to 110 gallons for storing rainwater
Connecticut – No regulations or laws against rainwater harvesting
Delaware – No regulations or laws against rainwater harvesting
Florida – No regulations or laws against rainwater harvesting
Georgia – The Department of Natural Resources, Environmental Protection Division regulates water resources; state plumbing code allows rainwater harvesting for outdoor use
Hawaii – No regulations or laws against rainwater harvesting
Idaho – Legal to capture rainwater off roof structures and the ground if the rain has not entered a natural waterway
Illinois – Local government can regulate rainwater harvesting per state plumbing law; rainwater can only be used for nonpotable uses
Indiana – No regulations or laws against rainwater harvesting
Iowa – No regulations or laws against rainwater harvesting
Kansas – No regulations or laws against rainwater harvesting
Kentucky – No regulations or laws against rainwater harvesting
Louisiana – No regulations or laws against rainwater harvesting
Maine – No regulations or laws against rainwater harvesting
Maryland – No regulations or laws against rainwater harvesting
Massachusetts – No regulations or laws against rainwater harvesting
Michigan – No regulations or laws against rainwater harvesting
Minnesota – Regulated through the Minnesota Plumbing Board, which requires permitting and code compliance
Mississippi – No regulations or laws against rainwater harvesting
Missouri – No regulations or laws against rainwater harvesting
Montana – No regulations or laws against rainwater harvesting
Nebraska – No regulations or laws against rainwater harvesting
Nevada – Residents are allowed to collect rainwater off of a single-family roof for non-potable domestic use
New Hampshire – No regulations or laws against rainwater harvesting
New Jersey – No regulations or laws against rainwater harvesting
New Mexico – Regulated through the State Engineer Office; no specific requirements exist for outdoor uses; indoor uses must meet water quality standards
New York – No regulations or laws against rainwater harvesting
North Carolina – Rainwater harvesting is encouraged due to water conservation efforts
North Dakota – No regulations or laws against rainwater harvesting
Ohio – Rainwater harvesting is legal, but there are codes and regulations that must be followed
Oklahoma – Encouraged through state legislation: Water for 2060 Act
Oregon – Rainwater harvesting is legal, but only using rooftop surface water
Pennsylvania – No regulations or laws against rainwater harvesting
Rhode Island – No regulations or laws against rainwater harvesting
South Carolina – No regulations or laws against rainwater harvesting
South Dakota – No regulations or laws against rainwater harvesting
Tennessee – No regulations or laws against rainwater harvesting.
Texas – Highly encouraged. Some counties even offer a tax incentive. And there is an exemption on sales tax for rainwater harvesting systems
Utah – 2,500 gallons max for rainwater harvesting systems. A permit is required
Vermont – Regulated through the Department of Environmental Conservation – 2017 Vermont Stormwater Management Manual Rule
Virginia – Regulated through state legislature and state plumbing code
Washington – No regulations or laws against rainwater harvesting
West Virginia – No regulations or laws against rainwater harvesting
Wisconsin – No regulations or laws against rainwater harvesting
Wyoming – No regulations or laws against rainwater harvesting
6. What are the benefits of rainwater collection?
Rainwater harvesting has a variety of benefits, which is why it’s becoming increasingly more popular.
These include:
It’s relatively clean
It’s a free source of water
It’s socially acceptable and environmentally responsible
It promotes self-sufficiency
It helps conserve water
It’s better for landscape irrigation and gardens because it isn’t chlorinated
It reduces stormwater runoff from homes and businesses
It helps solve drainage problems on your property while providing you with free water
It utilizes simple technologies that are inexpensive and easy to maintain
It can be used as the main source of water or backup source of water for wells and municipal water
It allows for a system that can be easily retrofitted to an existing structure or built during a new home construction
Its system is flexible and can be modular, allowing expansion, reconfiguration, or relocation (if necessary)
It can provide an excellent emergency source of water
It is sodium-free, which is important for persons on low-sodium diets
7. What are the uses for harvested rainwater?
Rainwater can be used in almost all the same ways that other water supplies are used (i.e., well, etc.).
If you intend to use the water for drinking, food preparation, and other direct human consumption, then you’ll need to filter the water to remove pathogens, grit, and other particles.
If you’re not able to filter it, we recommend boiling it at a rolling boil for at least one minute to kill disease-causing organisms.
Here are the top uses for rainwater (with necessary filtration in mind):
Outdoor Uses
- Garden and landscaping
- Swimming pools
- Livestock water
- Household chores like car or dog washing
- Water features like birdbaths or fountains
- Fire suppression or emergency water
Indoor Uses
- Washing machine
- Dishwasher
- Hot tub, bath, or shower
- Toilet
- Utility sink
9. Why is rainwater harvesting important?
Rainwater harvesting is important because it’s one of the best ways we can conserve water.
Water conservation gains have largely been achieved inside our homes, so we need to start looking for ways that we can conserve water outdoors as well.
Rainwater harvesting is a major way we can do this…it’s time we all start looking at implementing this!
10. How much rain can you collect?
The amount of rainfall you can collect is governed by the following formula:
1″ of rain x 1 sq. ft. = 0.623 gallons
The easiest way to remember this formula is by remembering that 1 inch of rainfall over 1,000 square feet will yield 623 gallons.
To calculate the amount of rainwater you can collect, you need to know the annual average precipitation for your area.
We recommend looking at the NCDC Monthly Precipitation Probabilities and Quintiles.
Once you find the closest weather station to you, use the 0.5 row to determine your annual average precipitation.
Then, use a rainwater collection calculator to determine your total rainwater collection potential using those values.
11. What are the different methods for collecting rainwater?
There are a few different methods for harvesting rainwater.
Here are the most common methods if you’re interested in getting started.
Rain barrels
This method is the most common.
It involves installing a barrel at a gutter downspout to collect rainwater.
The actual barrel may be a recycled barrel or a new commercially available rain barrel.
The pros to this system are that it is easily implemented by anyone with a residence and that barrels are readily available in your community.
Additionally, the barrels don’t take up much space, and they can fit into any situation.
The cons are that the capacity of the barrels is only 50 to 100 gallons, and the barrels can easily overflow.
“Dry” system
This system is a variation of a rain barrel setup.
It involves a larger storage volume, which means the collection pipe “dries” after each rain event as it empties directly into the top of the tank.
The pros of the “dry” system are that it can store a large amount of rainwater, and it’s less expensive to implement.
It’s also great for climates where rainfall happens with infrequent, larger storm events, and it’s a less complicated system to maintain.
The con of the “dry system” includes the fact that the storage tank must be located next to your house.
“Wet” system
This system involves locating the collection pipes underground to connect multiple downspouts from different gutters.
The rainwater will fill the underground piping, and the water will rise in the vertical pipes until it spills into the tank.
The downspout and underground collection piping must have a water-tight connection in order for this to work.
The elevation of the tank inlet should also be the lowest gutter on the house.
Some pros of this system include having the ability to collect water from your entire collection surface and having the ability to collect from multiple gutters and downspouts.
The tank can also be located away from your house.
Some cons of this system include the fact that it’s more expensive to implement because of the underground piping.
12. What are the components of a complete rainwater collection system?
For a complete rainwater collections system, here are the features you’ll need:
Roof surface: Make sure you have a roof surface suitable for rainwater harvesting
Gutter protection screening: Helps to keep large debris from entering your gutters
Gutter: You can collect rainwater from any type and shape of gutter
Rain head: This is an additional filtration opportunity
First-flusher diverter: This helps prevent the first flush of contaminated rainwater from entering the tank
Tank screen: This is installed on the tank entry point to keep mosquitos and pests out
Rainwater tanks: These come in all shapes and sizes to hold your rainwater
Insect proof flap valve: This element of your rainwater system keeps mosquitos and pests out
Auto-fill system: This is installed to always keep a minimum amount of water in the tank
Pump system: This provides pressurized rainwater to distribute the rainwater or connect to an irrigation system
Irrigation filter: This helps you catch any large debris that may have gotten through the pump
Water level indicator: This can be helpful in monitoring the water usage from the tank
Final Thoughts
If you’re interested in using rainwater harvesting as a source of water, get started today!
You’re merely harnessing a free water source that would otherwise go unused.
Use our tips above to help you create the system of your dreams.
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Disclaimer: we are not lawyers, accountants or financial advisors and the information in this article is for informational purposes only. This article is based on our own research and experience and we do our best to keep it accurate and up-to-date, but it may contain errors. Please be sure to consult a legal or financial professional before making any investment decisions.
Prior to starting Gokce Capital, Erika received a Bachelor of Architecture from the University of Southern California and a graduate degree in Urban Policy from Columbia University. She worked as both an architectural designer and engineer in New York before joining the New York City Department of Housing Preservation and Development.
Erika currently lives in the New York Metropolitan area with her spouse, daughter and cat. She is originally from Chicago and still considers herself a midwesterner at heart.
Erika also loves to read, write and travel (fun fact, she has visited all 50 states and more than 30 countries!). Her new book, Land Investing Mistakes: 11 True Stories You Need To Know Before Buying Land, is now available on Amazon.