Collecting rainwater for your tiny home simple as leaving out open containers during a rainy day. But if you’re looking for a more integrated solution, the good news is that setting up a rainwater collection system is an incredibly easy DIY project. 

So, how do you set up rainwater harvesting for tiny house living? You’ll need your primary components namely the catchment area, downspout, the first flush diverter, the storage bin, and a pressure pump

Not sure how to get started? In this article, we delve into the logistics of rainwater collecting, as well as clear up some myths regarding the legality of rainwater harvesting in various states in the US. 

How Do You Store Rainwater In Your Tiny Home?

Your choice of storage depends on your consumption needs. Most people use the following items for rainwater collection:

  • Trash bins
  • Barrels
  • Plastic drum
  • Soft PVC container
  • Rain pillow
  • Intermediate bulk containers (IBC) totes

If you’re looking for something more permanent and with more carrying capacity, going all out with your own water cistern will definitely provide your household’s daily needs. 

For the most part, rainwater storage is passive. Little maintenance is needed once you set up the system. We suggest buying pumps with filters, or making your own out of DIY objects, before it enters your tiny home. This way you can be sure that the water you collect is clean. However, some precautions will be necessary if you live in colder climates. 

How Do You Winterize Your Rainwater Collection System? 

Winterizing your harvesting system is a necessary step to prevent damage to pipes and the overall system. As is the standard winterization procedure, make sure to drain all of your rainfall containers. This includes any pipes and supply lines that connect to the catchment system. 

If you’re planning to depend on your collection system throughout the winter, your foremost concern is preventing water stillness. An easy way to do this is by adding an aerator that provides a steady stream of air in the containers, which will prevent the water from freezing. 

You could also introduce a heat pump into your water system so your containers never fall below a certain temperature and freeze off. Some builders place their water containers in a closed shed, and heat that entire space to prevent the water in the containers from freezing off.

Regardless of the situation, it’s important to keep your supply line buried or heated to prevent pipes from bursting. 

Can You Still Use Collected Rainwater During Winter?

In situations where you don’t have these systems in place, draining your supply is the obvious option. If you’re keen on saving water you’ve collected throughout the year, you could transfer your rainwater to smaller, more portable containers and transfer them to your tiny house. Buy containers with a spout so you can easily collect water for everyday use. These 7 gallon containers from Amazon are a great deal. 

What States Is It Illegal to Collect Rainwater?

Unless you’re planning to build a dam or reservoir in your property, you don’t have to worry about committing a federal crime. Stories you’ve heard of illegal rainwater collection were probably done on a larger scale, or exaggerated. The truth is that rainwater collection in the US is not only legal but encouraged in some states.

However, government restriction does exist for some states. In certain areas, the Federal Government has set up certain limits regarding the amount of rainwater you can collect. For example, in the state of Utah, unregistered individuals may collect amounts not exceeding 100 gallons, while registered individuals may collect rainwater not exceeding 2,500 gallons. 

There are no restrictions for collection for the following states:

Alabama, Alaska, Connecticut, Delaware (with incentives), Florida (with incentives and rebate benefits), Hawaii, Indiana, Iowa, Kentucky, Maine, Maryland (with incentives), Massachusetts, Michigan, Minnesota, Mississippi, MIssouri, Montana, Nebraska, New Hampshire, New Jersey (with rebate programs), New Mexico, New York, Oklahoma (possible grants), Pennsylvania, Rhode Island (tax credit), South Carolina, South Dakota (few statutes on water rights), Tennessee, Vermont, Virginia (tax credit), Washington, West Virginia, Wiconsin, and Wyoming. 

The states with more nuanced rainwater collection laws are:

  • Arizona: The State of Alabama allows rainwater harvesting. In fact, two House Bills support this. House Bill 2363 establishes a committee to govern macro-harvested rainwater for scientific research and investigation on its potential impact on water rights. House Bill 2830 allows cities and towns to establish funds for rainwater harvesting systems. 
  • Arkansas: Some restrictions apply. The Arkansas Code Annotated 17-38-201 of 2014 by the State Board of Health states that “the use of a harvested rainwater system used for non-potable purpose [is allowed] if the harvested rainwater system is: (1) designed by a professional engineer licensed in Arkansas; (2) designed with appropriate cross-connection safeguards; and (3) complies with Arkansas Plumbing Code.”
  • California: The Rainwater Capture Act of 2012 makes it legal to collect rainwater in California, as long as it is in compliance with the requirements set by the California State Water Resources. A permit may be needed. Residential, commercial, and government landowners are allowed to install rain barrels for specified purposes. 
  • Colorado: The House Bill 16-1005 passed in 2016 allows the collection of rainwater with a roof catchment system using two rain barrels, with capacities not exceeding 110 gallons for both. The collected rainwater may only be used for outdoor purposes such as irrigation and gardening. 
  • Georgia: Harvesting and collection is legal but is regulated by the Department of Natural Resources in the Environmental Protection Division. Rainwater harvesting is legal as long as it is limited to outdoor use. 
  • Idaho: Regulations only apply to rainwater that has entered natural waterways. 
  • Illinois: Rainwater harvesting is legal but homeowners are required to submit the design, location, and architectural requirements of the collection structure under the Homeowners’ Solar Rights Act within 120 after a homeowners’ association. 
  • Kansas: Considered legal but a permit issued by the Department of Agriculture may be required. The Kansas Water Appropriation Act secures the people’s right to harvest rainwater for non-domestic uses. 
  • Louisiana: Statewide statutes require covers cistern and water tank. Rainwater is otherwise legal and non-restricted. 
  • Nevada: Passed in 2017, the NB74 allows the collection of rainwater under the grant of a water right. Rights must be used for its intended purpose or else it may be revoked. 
  • North Carolina: Considered legal but is regulated by the 2011 House Bill 609 which states that the Department of Environment and Natural Resources will provide assistance on water efficiency, including harvesting rainwater. 
  • North Dakota: No official mandates mentioning if rainwater collection is illegal. Rain barrels are recommended for rain harvesting. 
  • Ohio: Rainwater harvesting systems are legal even for potable purposes, provided that water systems supply drinking water to 25 people or less and is regulated by the Ohio Department of Health, according to Ohio Rev. Code 3701.344. 
  • Oregon: Only harvesting systems on roofs are allowed. Alternate methods of collection are allowed but legal advice is required before construction. 
  • Texas: Designs for the collection system should be incorporated into the design of the building, according to House Bill 3391, and a written notice to the municipality is required. 
  • Utah: Rainwater collection is allowed but restrictions apply. According to the Senate Bill 32 of 2010, a registered individual with the Division of Water Resources may collect no more than 2,500 gallons of rainwater, while unregistered individuals may collect no more than 100 gallons. 

Note: These are the laws published at the time of writing. This website is not affiliated with any government agencies and should not be used for legal advice. We encourage readers to double check their state legislature for the most recent mandates on rainwater harvesting. 

Setting Up Your Tiny Home’s Rainwater Catchment System

Preparation and Calculation 

Although the set up itself is simple, you’re going to need to make some calculations just to set your expectations right. If you live in temperate climates with scattered rains, chances are you won’t be able to live off your rainwater completely. However, you can still use this to supplement the main supply line and lower your water bill. 

How much rainwater can my tiny house collect?

An easy formula provided by the Tiny House Design and Construction Guide will guide you with your monthly rainwater collection. 

Catchment Area (square feet of roof, shed)xRainfall Depth (inches)x0.623 Conversion Factor=Harvested Water (gallons)

Keep in mind that your rainwater collection system can only do so much. Can you live off your system completely? That depends on how intricate your system is. The bigger your catchment area, the more rain you get every month, and the more you can store, the better chances of you relying on this system.

To figure out the best rainwater harvesting system for your tiny house, ask yourself the following questions:

How much water does my household consume daily?

According to the United States Environmental Protection Agency, the average American household uses more than 300 gallons of water daily, 70% of which is used indoors.

Flushing the toilet, showering, and running the faucet are the top sources of consumption. Naturally, the numbers won’t be as high in a tiny house, and can be further reduced by getting water-efficient appliances and adopting water-saving techniques.

On average, the water consumption for everyday activities are as follows:

Activity / DeviceGallons of Water
Shower2 to 4 gallons per minute; 15.8 gallons for an average shower time
Flushing the toilet1.6 to 2 gallons 
Washing hands and dishes1 gallon per minute
Washing clothes15 gallons per load

How much rain do I receive per month?

The amount of rain you receive per month will determine the best storage size and how much rainwater you can expect to harvest. If you receive sporadic rains, with some months receiving more rain than others, it’s best to get a bigger storage container so you can keep excess rainwater throughout the drier seasons. You can estimate the amount of rainwater you’ll receive per month using climate data in your location.

How frequently will I move my tiny house?

How frequently you want to travel has more to do with your set-up than the actual harvesting. When you’re both off-grid and on the road, you want your water tank to be equally portable and reliable. This is just something to think about when setting up your own rainwater harvesting system. 

Parts of a Rainwater Catchment System 

1) Catchment Area

<picture of roof with rain barrels at the bottom> 

The catchment area refers to any surface where the rain first hits. In most tiny houses, this is usually the roof. If your tiny home has a flat roof, you could always build a separate collection area within your property. Naturally, the more surface area you have, the more rainwater you’ll be able to collect. 

Steel roofs are the perfect roofs for catching rainwater. They’re easy to clean and aren’t treated with harmful chemicals that could tamper with the water quality. Because of its smooth surface, the water will roll to the gutter and down to the downspout, maximizing your collection potential. 

Where To Get: You can get corrugated steel sheets from your local hardware store. If you want to save up on your project, you could look around for scraps or simply reuse old ones from your tiny house build. You can also order a pack of 10 corrugated metal roof sheets online. 

2) Downspout 


The downspout is what connects your gutters to the storage areas. You can fashion a downspout using a flexible pipe, or you could buy downspouts that are specifically manufactured for rainwater collection.

The diverter and filter are two separate things that are connected to the downspout. Think of the diverter as another outlet that separates the first flush of dirty rainwater from the clean water. The filter is usually made from a mesh, or if you’re paying extra, something a little more intricate, that will keep debris, insects, and all sorts of unwanted water away from your water supply.

DIY DownspoutBought Downspout
Cheap, can use existing materials for the project ($10 or less)Can go anywhere from $10 to $100, depending on brand and package inclusions
Can go with no filter option, or can be connected to a diverter that will filter out bad waterUsually comes with filters and diverters that will ensure clean water 
No labor costsNo more than $100 for gutter design and downspout installation
Not as durable as hard, prefab downspout and may be subject to rust, perforation, depending on the material usedReliable and will last a long time

Where To Get: Look for companies that specialize in rainwater collection. Rain Harvest Systems has a couple of options made from steel and plastic. You could also install your own using packs from Amazon. 

3) First Flush Filter


Aside from the mesh filter (usually made from fiberglass material or repurposed door screen), an extra filtration system is used to redirect the first flow of dirty water away from your catchment system. 

How do I filter rainwater from my roof?

The first flush filter, also called a rain barrel diverter, is a common contraption connecting the downspout and the collection area. This is usually made of PVC, with a ball inside that floats up, seals the hole, and allows cleaner water to go through your storage system. 

How does a rain barrel diverter work? 

The idea is that the first flush of water containing debris, dirt, and dust will flow downwards. As the rain continues to “clean” the water, the tube will fill up with cleaner water, all the while raising the foam ball until it seals the hole and diverts a cleaner water supply. 

Where To Get: RainReserve has a downspout and diverter kit that’s easy to install. Another great option from is the transparent 4 inch diverter from Rain Brothers that will allow you to monitor the rainwater’s clarity. 

4) Collection Area


The collection area simply refers to your storage units. It could be anything from trash cans to repurposed barrels. Most people use the standard 55-gallon drums and connect it with other similar capacity drums with PVC pipes to increase the overall capacity. 

Off-grid tiny houses that are more dependent on their collected rainwater for everyday use 275 gallon IBC totes. Your collection area really just depends on: a) how much water you consume on a daily basis; b) how frequently you want to use your rainwater; c) how much of the rainwater you will be consuming everyday. Consider getting portable storage options if you’re going to be moving your tiny house a lot. 

Does a rain barrel need to be elevated?

When setting up your rain barrel or IBC tote, elevation isn’t really the point here. What you should be aiming for is stability. Place your containers on some solid foundation so they don’t topple over during rains, earthquakes, or just sheer weight. 

Where To Get: You can purchase IBC totes and drums online, but you could also score these for a lower price when approaching manufacturers for their second hand containers. Just make sure these old containers didn’t contain harmful chemicals that could affect your water quality. 

If you’re willing to stretch out your budget, we suggest getting Rainwater Pillow kits. The 1,000 gallon pillow starts at $2,800 and includes everything you need from the pump to the downspout to the first flush diverter. It’s a fantastic portable, pretty lightweight option that you can easily store and stow when you need to be on the road. 

5) Pressure Pump


If you think gravity alone can’t push water to your tiny house, installing a pressure pump or water pump is a good idea. You don’t have to go for the $200 - $300 options with 800-1,000 gallon capacities per hour. Remember, you’re fueling a tiny home, which means you can get away with something lighter. 

Where To Get: This 250 gallons/hour pump is a pretty great option for tiny houses. If you don’t want to simplify the process and pump water straight out of your barrel, a barrel water pump will also do the trick. 

Harvesting Rainwater For Your Tiny House: Installation Guide

Tiny House Listings has a comprehensive video when he built his own harvesting system. Instead of using his own roof, he built a separate collection area that houses his three IBC totes. 

Hay Woods and Wetlands uses a similar but smaller-scale rainwater collection system. In the other half of the video, he shows how to create a collection area from scratch, on the spot, using recycled materials for his downspout, a barrel pump, and a standard 55 gallon barrel. 

Live Off Your Rooftop

Do you have what it takes to build your own harvesting structure? Really, as long as you have a roof, you’re pretty much good to go. Whether you’re using a 55 gallon drum, a 275 gallon IBC tote, or a small trash can, building your own rain collection structure can be a fun and meaningful DIY project. 

Whether you want to depend on this for off-grid living or just want to design one to make your lifestyle a little more environmentally-friendly is entirely up to you. 

About Us

Manuela and Ivan from Tiny House Bloom

Hey, there! We're Ivan and Manuela from Croatia, and we're crazy about tiny houses. We don't own one (yet).

This website is a result of our passion to share all the knowledge, photos, tips and tricks that we were able to learn while studying everything possible about the tiny house movement.