How to Harvest and Collect Rainwater - Backyard Boss
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How to Harvest and Collect Rainwater

If you want to save money, save resources, and save the planet, you should try harvesting rainwater. It’s fairly simple to set up a system, especially when you have a comprehensive guide like this one to lead the way!

This guide includes information on the benefits of rainwater collection, where collecting rainwater is legal, and how to collect rainwater, to help you get started.

What Is Rainwater Collection?

Rainwater harvesting, which is also known as rainwater collection and rainwater catchment, is a popular method to save water and live more eco-friendly lives. Rainwater harvesting involves collecting water run-off from structures and surfaces.

Most commonly people harvest rainwater from their roofs, collecting it in their gutters, channeling the water through a downspout which then directs the water towards a storage vessel, like a barrel. The water is collected for later use, for things like watering plants.

Systems range in how complicated they are. Some people have simple rain barrel systems while others have large cisterns that collect enough rainwater to supply their entire household.

Why Would You Want to Collect Rainwater?

A better question is why WOULDN’T you want to collect rainwater? There are so many benefits to collecting rainwater!

Below are just a handful:

  • Rainwater is FREE so collecting it helps you save money.
  • Collecting rainwater allows you to have total control of your water supply
  • By saving water you do your part to save the planet
  • If something happens to the water supply in your area, you have a back-up supply
  • Rainwater is better for feeding plants because it’s not chlorinated
  • Collecting rainwater will solve the drainage problems on your property
  • It’s inexpensive to set up a rainwater system

Uses for Collected Rainwater

You set up your gutter guards, pipe system, and barrels. A huge storm hits and you’ve collected a decent amount of water.

Now what? What can you actually use rainwater for?

You can use rainwater for basically everything that you use normal tap water for EXCEPT for drinking.

Below are some things that you can use rainwater for:

  • Watering your plants
  • Watering your lawn
  • In your swimming pool
  • Washing your vehicle
  • Washing your pet
  • Livestock water
  • Water features like fountains
  • In your washing machine
  • In your dishwashers
  • In your toilet


Considering how there are drinking water shortages not only around the world but also across our country, it’s inexcusable wasteful to use it for tasks in which rainwater would suffice. By using rainwater you really can make an impact, lessening your environmental footprint.

Is It Illegal to Collect Rainwater?

Rainwater harvesting is not illegal anywhere in America. However, there are some states that have restrictions on rainwater catchments. Before setting up your system, be sure to look up your state’s specific guidelines.

The restrictions typically will limit how much water you can collect and the methods in which you can collect it. These restrictions are normally in place because the government wants to ensure that the hydrologic cycle in an area is not disrupted.

Many studies have contradicted this rationale, proving that the amount of rainwater collected by individual homes should have no effect on hydrologic cycles on a macro-level. Especially since most collected rainwater is used for gardening and lawncare purposes, so it’s returned to the ground.

How Much Rainwater Can You Collect?

By 2021, most states have shifted their laws to fully allow rainwater harvesting. However, there are still a dozen states with some restrictions, all of which are listed below.

  • Arkansas: You may only harvest rainwater with a professionally designed system that has appropriate cross-connection safeguards and complies with Arkansas Plumbing Code.
  • California: You may collect rainwater as long as your system is in compliance with the California State Water Resources Board requirements.
  • Colorado: You may collect up to 110 gallons of rainwater at a time for outdoor purposes on the property it’s collected on.
  • Georgia: You may only harvest rainwater for outdoor use.
  • Illinois: You may harvest rainwater but you must follow rules outline in the Green Infrastructure for Clean Water Act and report your system to your Home Owner’s Association.
  • Kansas: You may collect rainwater but you have to get a permit issued by the Department of Agriculture.
  • Nevada: You may collect rainwater if you are granted a water right, which will state the rainwater’s intended purpose.
  • North Carolina: Rainwater harvesting is legal in North Carolina, however, it is regulated by the Department of Environment and Natural Resources.
  • Ohio: Rainwater harvesting is legal in Ohio, but it is regulated by the Ohio Department of Health.
  • Oregon: You can only harvest rainwater in Oregon from a rainwater catchment system on a rooftop surface.
  • Texas: If you collect rainwater in Texas your catchment system has to be incorporated into the design of your building and you have to give written notice to your municipality.
  • Utah: You may collect up to 2,500 gallons of rainwater if you are registered with the Division of Water Resources and only 100 gallons if you are not registered.

What Are the Methods of Rainwater Collection?

From method to method, what really differs is the size of rainwater catchment systems. They otherwise all operate under the same principles and similar designs.

Rain Barrel

Green plastic rain catcher barrel to catch and store fresh chlorine-free water.

This is the most common method because of its simplicity. All you have to do is place a high-quality rain barrel or a recycled barrel under a gutter downspout to collect rainwater.

This option is affordable, easy to set up, and great for more compact spaces. However, with this method, you’re typically only able to store between 50-100 gallons, so it can easily overflow, wasting collection opportunities.

If you love this method because it’s affordable, consider making your own rain barrels!

Dry System

Natural rainwater capture system following the dry system concept.

The dry system is similar to the rain barrel one, however, it involves a larger storage volume. The collection pipes leak right into a large catchment system, relying on gravity. This system gets its name from the pipes “drying” after each rain because they empty into the top of a tank.

This system is perfect for people who live in areas with infrequent but powerful rainstorms. It’s also inexpensive to install, and maintenance is fairly simple.

The downside of this system is that the large tank has to be next to your house which can be an eyesore. Consider painting something on it, like flowers, to make it more visually appealing.

Wet System

This is the most complicated method for rainwater collection because it involves using multiple collection pipes underground which connect various downspouts in different gutters.

Rainwater fills up the underground piping so that water rises in the vertical pipes until it spills out into the collection tanks. For this system to work, the downspouts and underground collection pipes must have water-tight connections so that they do not leak, which means some difficult maintenance can be required.

Your tank’s inlet must be below the lowest gutter in your house, however, otherwise it can be placed away from your home which allows for some flexibility. Allowing you to collect from multiple sources and the entirety of collection surfaces, this is a great system for people who want to store a lot of water. Its downside is that it can be expensive and difficult to install.

How to Harvest Rainwater

Step One: Prepare Your Water Collection Surface

Make sure that your roof surface is fine for collecting rainwater. It likely is, most roof surfaces are. You need to have high-quality gutter guards installed to keep debris out of your gutter. The shape of your gutters doesn’t matter, you can collect rainwater from any type of gutter.

Step Two: Add Additional Filtration

If you want additional filtration, install a rain head on the end of your downspout. You can also install a first-flush diverter, which will help keep your rainwater clean by preventing the first flush of contaminated rainwater from entering the tank.

If these first two options don’t fit your fancy, you can also try a tank screen. Tank screens are installed at the tank’s entry point and keep mosquitos and other pests from infiltrating the water supply.

Step Three: Install Your Tank

When you decide on what tank you want to use, the most important factor to take into consideration is how much water you want to store. Someone looking to store 100 gallons of water will need a very different tank than those looking to store 2,500 gallons.

You also should consider what system you are using since different tanks are more conducive to the rain barrel, dry system, and wet system water collection methods. Which method you choose will also dictate where your tank can be located.

Step Four: Set Up Your System

This step will look very different for people depending on which system they have chosen to install. A rain barrel system will just require you to place a barrel under a downspout while a wet system will require some construction.

Step Five: Keep It Simple or Upgrade Your Water Catchment

How advanced your system needs to be depends on what you will be using the rainwater for. If you are just using it outside, then you don’t need a lot of fancy gadgets. However, if you are using it for purposes like showering, then you’ll probably want to make sure that it stays clean and doesn’t have bacterial growth.

Some gadgets to consider including are an insect-proof valve, an auto-fill system, a pump system, an irrigation filter, and a water level indicator.

The Bottom Water Line

At this point, your brain is probably overflowing with knowledge about rainwater collection!

Hopefully, we didn’t let any answers fall through the cracks, but if we did, be sure to comment below with your questions. And, as always, if you found this guide helpful share it so other people can learn from it too.