
A rain gutter water catcher is a simple and effective way to conserve water, and it's surprisingly easy to install. According to our previous section, a typical household can collect up to 600 gallons of water from a single inch of rainfall.
This amount of water can be used for watering plants, washing cars, and even flushing toilets. In fact, a single gallon of water can save up to 1.3 pounds of water per day.
By installing a rain gutter water catcher, you can reduce your water bills and help the environment. Rainwater is free and clean, making it an ideal alternative to municipal water supplies.
Discover more: Gutter Rain Collector
System Design and Components
A complete rainwater collection system starts with your roof surface, which can be nearly any type and shape of gutter. You don't need a special gutter for harvesting rainwater.
Your gutters should have some sort of gutter protection screening to keep large debris from entering the gutters. A rain head (downspout filter) can also provide self-cleaning filtration options. A first-flush diverter helps prevent the first flush of contaminated rainwater from entering the tank.
Here's a list of the key components you'll need to create a complete rainwater collection system:
- Roof surface (gutter)
- Gutter protection screening
- Rain head (downspout filter)
- First-flush diverter
- Rainwater tank
- Insect proof flap valve
- Auto-fill system
- Pump system
- Irrigation filter
- Water level indicator
System Design and Components

Rainwater collection systems can be as simple as collecting rain in a rain barrel or as elaborate as harvesting rainwater into large cisterns to supply your entire household demand.
You can collect rainwater from your roof, which is a great source of free water. Rainwater collection systems can be configured to supply your whole house and/or your landscape needs.
The basic components of a rainwater collection system include gutters, downspouts, and a storage vessel. These can be as simple as a rain barrel or as complex as a large cistern.
Rainwater can be used for irrigation, indoor non-potable use, and whole house, potable use. You can use rainwater for a variety of tasks, such as hand watering your lawn and garden, washing your vehicles, and refilling your fountains and fish ponds.
Here are some ideas for specific uses of rainwater:
- Hand water your lawn and garden
- Connect rainwater collection system to irrigation/sprinkler system
- Wash your vehicles
- Wash your pets
- Refill your fountains and fish ponds
- Refill your swimming pool
- Replace the use of tap water with rainwater to wash your driveways and sidewalks (if you don’t use a broom)
- Use it for all indoor non-potable fixtures (toilets and clothes washer)
- Use it for all potable needs when properly filtered and disinfected
- Use it for industrial processes instead of municipally treated water
A properly designed and installed rainwater harvesting system can provide an excellent back-up source of water for emergencies.
Dry System

The "Dry" System is a great option for collecting rainwater, especially in areas where rainfall happens with infrequent, larger storm events.
This method involves a larger storage volume, where the collection pipe empties directly into the top of the tank after each rain event. The result is a "dry" system that can store a large amount of rainwater.
One of the biggest advantages of the "Dry" System is its ability to store a large amount of rainwater. This makes it ideal for climates where rainfall happens with infrequent, larger storm events.
The system is also relatively inexpensive to implement and less complicated, making maintenance easier. This is a big plus for those who want to collect rainwater but don't want to break the bank.
Here are some key benefits of the "Dry" System:
- Can store a large amount of rainwater
- Great for climates where rainfall happens with infrequent, larger storm events
- Can be inexpensive to implement
- Less complicated system so maintenance is easier
Selector Valves
Selector Valves can be a game-changer for small rainwater harvesting systems, allowing you to control the flow of water and prevent overflow.

They can be used in conjunction with diverters to catch overflow from heavier rains, as seen in the example where two diverters are installed one higher than the other.
By installing a RainRouter Selector Valve on the bottom diverter, you can send excess water through a hose to direct it elsewhere, preventing overflow and ensuring your system functions efficiently.
This is especially useful for small systems where too much water can be a problem, and it's a great way to make the most of your rainwater harvesting setup.
A fresh viewpoint: Rain Water Drain Pipes
Downspout Compatibility Issues
If you have non-standard downspouts, don't worry, there are still solutions available. We carry diverter kits for 2" x 3" and 3" x 4" rectangular downspouts, and round downspouts between 3" and 4" in diameter, covering most standard residential and industrial sizes.
A Leaf Eater can be a great adapter for any rainwater system, adapting to round or rectangular downspouts, and even rain chains or scuppers. It's a surprisingly simple solution.
Readers also liked: 3 Rain Gutter
The Leaf Eater is a standard upgrade that requires a clean cut to the downspout for installation, which is a good thing if you have non-compatible downspouts. The cut is easy to make and seals well against the rubberized diverter head.
Plastic downspout material is inexpensive, easy to cut, and seals well against the diverter head, making it a convenient option.
You might enjoy: How to Cut a Rain Gutter
Building a Platform
To create a stable platform for your rain barrels, you'll need to level the area next to your downspout. Clear away any rocks and debris from the space.
The area should be flat, so if it's not, use a shovel to remove enough dirt to create a level surface. You'll want to make sure it's big enough to accommodate all of your rain barrels.
A layer of pea gravel is essential for good drainage and to keep water away from your home's foundation. Dig a 5-inch deep rectangle and fill it with 1/2 inch of pea gravel.
Worth a look: Level a Rain Gutter

To create a raised platform, stack concrete blocks on top of the pea gravel. They should be stacked sideways to provide a stable base for your rain barrels.
Here's a quick rundown of the steps:
- Level the area next to your downspout
- Clear away rocks and debris
- Remove dirt to create a flat surface
- Dig a 5-inch deep rectangle for pea gravel
- Fill with 1/2 inch of pea gravel
- Stack concrete blocks on top of the pea gravel
Increasing Inflow
A multi-barrel system can't fill any faster than water can get through the connection lines, so it's essential to match the inflow rate to the rate at which the system can fill.
To increase inflow without creating overflow issues, consider collecting from multiple downspouts, like the system that collects from two separate downspouts: one at each end.
A standard setup for a multi-barrel system is to connect the downspout to the barrel using a downspout elbow, which allows water to pour directly into the barrel.
Connecting multiple barrels to a single system can be done by setting them on a platform and connecting lengths of hose to the valves.
You can also increase inflow by using a system like the BlueBarrel System, which is very flexible and allows for customizations such as extra diverters to feed a single system from multiple downspouts.
Related reading: Water Dripping from Gutter but No Rain
In a standard setup, the most sound approach is to match the inflow rate to the rate at which the system can fill, otherwise you will have issues with backup.
Here are some key takeaways for increasing inflow:
- Collect from multiple downspouts to increase inflow
- Match the inflow rate to the rate at which the system can fill
- Use a system like the BlueBarrel System for flexibility and customizations
How Hard Does It Take to Overflow?
The amount of rain it takes to cause simultaneous overflow depends on the size of your rooftop and the rainfall intensity rate.
A smaller collection surface requires harder rains to see simultaneous overflow.
If you have a very large surface, you may see simultaneous overflow with just moderate rains.
The rainfall intensity rate can change from minute-to-minute, making it unpredictable.
In general, a larger rooftop means less intense rain is needed for overflow.
Take a look at this: Roof Top Garden
Blue Barrel Downspout
The Blue Barrel Downspout is a key component in any rainwater collection system. It's responsible for redirecting rainwater from the downspout into a linked system of barrels.
You can choose from three different diverter sizes for an easy-to-install and well-fitted downspout solution. A flexible-fit, rubberized downspout diverter is a popular option, as it intercepts rainwater flowing through a downspout and redirects it into a linked system of barrels.
The downspout diverter automatically redirects excess flow down the existing downspout once the barrels reach full capacity. This ensures that rainwater is efficiently collected and stored.
Here are some key features to consider when selecting a downspout diverter:
In order to install a downspout diverter, you'll need to connect it to the downspout and the linked system of barrels. This can be done using a downspout elbow, which should be attached to the downspout and the diverter.
System Assembly and Installation
To start assembling your rain gutter water catcher, you'll need to connect the downspout elbow to the downspout, making sure it's close enough to the downspout that you can connect it with the downspout elbow. Mark the downspout one inch below the height of the rain barrel, and use a hacksaw to cut the downspout at the mark.
Next, connect the barrel to the elbow, cutting a hole in the lid of the barrel if necessary to fit the end of the elbow inside. Cover the area around the hole with a metal screen to keep debris out. You can also place a filter at the top of the downspout to prevent leaves and other debris from running down the downspout and creating a clog in your rainwater collection system.
Some rainwater collection systems also require a first-flush diverter, which helps to prevent the first flush of contaminated rainwater from entering the tank.
Take a look at this: Rain Gutter Debris Filter
Collection System Assembly
Assembling the collection system is a crucial step in setting up your rainwater harvesting system. You'll want to start by connecting the downspout elbow to the downspout, marking the downspout one inch below the height of the rain barrel.
To do this, set the barrel next to the downspout and mark the downspout accordingly. Then, use a hacksaw to cut the downspout at the mark and attach the downspout elbow with screws.
A filter should be placed at the top of the downspout to prevent leaves and other debris from clogging your system. This is an important step to ensure the longevity of your rainwater collection system.
Next, connect the barrel to the elbow by cutting a hole in the lid of the barrel and covering the area with a metal screen. You can also connect additional barrels by setting them on a platform and attaching lengths of hose to the valves.
It's worth noting that a tank screen can be installed on the tank entry point to keep mosquitoes and pests out, while also providing additional filtration opportunities. This can be a great way to add an extra layer of protection to your system.
Here's a step-by-step list to help you assemble your collection system:
- Connect the downspout elbow to the downspout.
- Mark the downspout one inch below the height of the rain barrel.
- Cut the downspout at the mark and attach the downspout elbow with screws.
- Place a filter at the top of the downspout.
- Connect the barrel to the elbow.
- Connect additional barrels by attaching lengths of hose to the valves.
By following these steps and taking the time to properly assemble your collection system, you'll be well on your way to harvesting rainwater and reducing your water bill.
Raised Barrel Foundations
Raised Barrel Foundations are a creative way to install your BlueBarrel Rainwater Catchment System, allowing for a customizable fit to your space and personal style.
You can tailor your system to your needs with the DIY kit, which offers plenty of room for creativity. Check out the creative foundation ideas submitted by our DIY customers for inspiration.
A raised barrel foundation is a great option for areas with poor drainage or where you want to keep your system elevated. This type of foundation can also be used to create a visually appealing installation.
Some DIY customers have submitted their own creative foundation ideas, such as using wooden pallets or bricks to create a unique base. These ideas can be a great starting point for your own installation.
By using a raised barrel foundation, you can keep your system off the ground and out of the way, making it easier to maintain and access. This can be especially useful if you have limited space or want to keep your system looking tidy.
System Maintenance and Optimization
Regular maintenance is crucial to keep your rainwater collection system running smoothly. It's recommended to clean the gutters at least twice a year to ensure proper water flow.
Check the gutter protection screening regularly to ensure it's free from debris. This will prevent large particles from entering the gutters.
A well-maintained rainwater collection system can last for many years. To keep it in good condition, inspect the tank screen and first-flush diverter regularly.
Related reading: Gutters for Flat Roof
The tank screen should be cleaned or replaced if it becomes clogged. This will prevent mosquitoes and pests from entering the tank.
Here are some key maintenance tasks to perform regularly:
- Check the tank level indicator to monitor water usage.
- Clean the pump system and irrigation filter to prevent clogs.
- Inspect the insect-proof flap valve to ensure it's functioning properly.
By following these simple maintenance tasks, you can ensure your rainwater collection system remains in good working condition and continues to provide you with a reliable source of clean water.
Water Collection and Storage
Collecting and storing rainwater is a simple and effective way to conserve water and reduce your environmental footprint. Rainwater harvesting is the process of collecting and storing rainwater from rooftops and other impervious surfaces, typically using gutters and downspouts.
The idea of rainwater harvesting has been around for a long time, but it's gaining popularity as a sustainable alternative to traditional water sources. Many countries, including Germany and Australia, have made rainwater harvesting a norm, and it's becoming increasingly popular in the US due to the green building movement.
To collect rainwater, you'll need to install a rainwater collection system, which typically consists of a rain barrel or tank, gutters, and downspouts. You can collect rainwater from any type and shape of gutter, and you don't need a special gutter for harvesting rainwater.
Rainwater is a relatively clean and free source of water, making it an ideal alternative to municipal water supplies. You can use it for irrigation, indoor non-potable uses, and even for whole-house potable use when properly filtered and disinfected.
Here are some common uses of collected rainwater:
- Irrigation
- Indoor, non-potable use (e.g., washing machines, toilets)
- Whole-house, potable use (when properly filtered and disinfected)
- Washing vehicles and pets
- Refilling fountains and fish ponds
- Replacing tap water for washing driveways and sidewalks
To calculate the amount of rainwater you can collect, you'll need to know your annual average precipitation for your area. You can use a precipitation map or find an exact amount by looking at the NCDC Monthly Precipitation Probabilities and Quintiles.
Frequently Asked Questions
How fast will a 50 gallon rain barrel fill up?
A 50-gallon rain barrel can fill up in about one hour during a moderate rainstorm. This is equivalent to collecting about 1/8 inch of rain per hour on a 500 square foot roof.
Are rainwater barrels worth it?
Rainwater barrels are a worthwhile investment, saving you money and conserving water resources for your plants and outdoor spaces
Sources
- https://4perfectwater.com/blog/gutter-water-catcher-meet-rainwater-harvesting
- https://www.watercache.com/education/rainwater-harvesting-101
- https://permies.com/t/65544/Built-Stand-Rainwater-Catchment-System
- https://www.bluebarrelsystems.com/blog/demystifying-downspout-diverter-for-rain-barrels/
- https://www.wikihow.com/Build-a-Rainwater-Collection-System
Featured Images: pexels.com