DIY Solar-Powered Rain Barrel Irrigation

My wife has been putting in lots of new garden beds, so we’ve been thinking through how to best and most efficiently water them. Cue: irrigation! She sent me down a rabbit hole for today’s project—our DIY solar-powered rain barrel irrigation system.

Last summer my big project was setting up our DIY Smokeless Fire Pit. Brit was originally skeptical, but because it got such a great response from readers, she told me to run with my rain barrel irrigation system idea. And I was keen on diving into another in-depth project.

First Brit chose the rain barrel and told me the rest was up to me. So I went all in. In this tutorial, I will walk you through the steps to construct your own solar-powered rain barrel irrigation system. Let’s f**king go!

Why rainwater & solar

Rain barrels have been around for ages, capturing and storing rainwater. But why not take it a step further? That’s what I told Brit. She just wanted a rain barrel to fill up her watering can. But I don’t know when to quit and just had to turn it up to 11.

By adding a solar-powered water pump to your setup, you can use THE POWER OF THE SUN to transport water to your garden beds! All without using the power grid or your muscles.

Adding this system offers a ton of advantages. Using collected rainwater instead of municipal water helps lower water costs and leads to long-term savings. But also it’s an environmentally conscious solution that reduces your reliance on the city’s water supplies. And it just makes you feel good.

This was our first foray into using solar energy. We don’t have solar panels on the house, so this was fun for me to dig in to. Solar energy is the perfect choice for powering your rainwater collection system. It’s a clean, plentiful, and renewable power source that generates zero greenhouse gas emissions.

Solar panels need minimal upkeep and can produce electricity for over 25 years. But also, by using solar energy, you can gain greater self-sufficiency and reduce grid reliance. See how self-sufficient I look installing our solar panel below?

Customization ideas

As you gather materials for this DIY project, remember that it’s not always necessary to buy everything brand new. In fact, repurposing materials can be both eco-friendly and cost-effective. For instance, rather than purchasing a rain barrel, think about using a sizable container like a trash can or an old drum.

Often found on Facebook Free or super cheap. But my wife is high maintenance and had a specific rain barrel that she wanted to use. So we went with that (she is the chief creative director, after all). You can also reuse hoses and pipes from previous projects, as long as they’re in good shape and have the appropriate diameter.

Make sure you conduct enough research on your water pump to find what is most suitable for your setup. Take into account your garden’s size and water needs. You must also consider the sunlight availability in your region and search for a battery capable of storing sufficient energy to run the pump even in the absence of sunlight.

You might also want to find a pump with a timer or controller, which will assist you in regulating water flow to your garden beds. Selecting the proper materials for your system will significantly impact its performance.

Assembling the system

I found it useful to conceptualize this project in three main parts: structural, mechanical, and electrical. So that’s how I am organizing this tutorial. Hopefully it makes sense.

If you are like me, you’ll want to jump right into the electrical or mechanical aspects. But I discovered that determining placement and distances for the structural components early on is crucial.

So, decide where the rain barrel will be located, how you plan to elevate it, and the positioning of the mechanical tote relative to the barrel and garden beds. And, of course, make sure it’s near the gutter that will be diverting the rainwater.

Part 1: Structural considerations

Location

1. Select the appropriate rain barrel. Pick one that meets your needs in terms of size and location. Take into account your area’s rainfall levels and the size of your garden. Obviously, a larger barrel holds more water, but it is also bulkier, harder to maneuver, and occupies more space. We used a 50 gallon flat-back barrel.
2. Position your rain barrel near a downspout. Remove any grass and level the ground where you plan to seat the system.
3. Next, elevate the barrel. I used cinder blocks and pavers to raise mine. I wanted it higher so I could still easily fill a watering can. But I also didn’t want it to obstruct the window more than necessary.
4. Now consider the placement of the mechanical box. Visualize the tubing running from the barrel to the garden irrigation hoses. Understanding the pump’s one-way flow and determining its position inside the box is essential.

Gutters

1. Remove and replace gutter sections to direct rainwater to the barrel if needed. I used a single 90-degree elbow piece to navigate the house’s corner.
2. Install a downspout diverter to funnel rainwater into the barrel. You may need to add a debris filter to the downspout diverter if your barrel doesn’t have any type of initial filtration.

Barrel setup

1. Now on to the rain barrel setup. I suggest attaching a dual-spigot to the rain barrel. Since the pump hose will always be connected, an additional outlet for filling watering cans will be useful.
2. Attach a garden hose inlet filter to the spigot leading to the water pump. Although my rain barrel’s top intake has a mesh filter for larger particles, I recommend extra filtration for the water entering the pump.

Part 2: Mechanical setup

Mechanical Box

I suggest using a 7-gallon plastic tote for your mechanical box. You could go bigger if your garden size requires a larger pump and battery.

1. I began by securing a piece of scrap wood to the bottom of the tote to mount the pump. You could bolt it, but I used Flexseal rubber adhesive that I had on hand. Once attached to the bottom, mount the pump with four small screws.
2. When attaching the pump, take note of the pump’s flow direction. This will dictate which end of the tote you want the pump to sit.
3. Drill or cut out two holes big enough for ½-inch tubing on the sides of the tote that align with the pump’s intake and outtake.

Intake/Outtake

1. With everything in place, I started working on the tubing. Use ½-inch clear plastic tubes to make connections going in and out of the pump.
2. Determine the length of clear plastic tubing for each end of the pump. This will depend on your barrel’s location and where your irrigation tubing begins. My setup required 1-2 feet.
3. Attach each clear plastic tubing section to the pump’s intake and outtake with small hose clamps.
4. Attach a brass female hose fitting connector (½” barb x ¾” female hose) with another small hose clamp to the clear plastic hose on the barrel end.
5. At this point, you could connect it to the rain barrel spigot. Or in my case, connecting directly to the garden hose inlet filter coming off the spigot.
6. Do the same for the other plastic hose on the irrigation side. But this side will use a male brass hose fitting connector (½” barb x ¾” male hose).

Irrigation Lines

Now you should consider trenching some of the irrigation pathways paths before setting up the hoses. It’s not necessary, but it can make the setup look cleaner. Dig about 4-6 inches deep along your desired water pump outtake path.

1. Start setting up the irrigation. I recommend getting a starter kit with everything you need if you’re not experienced with garden irrigation systems.
2. Connect another small filtration apparatus (included in kit) to the pump hose to ensure particles don’t get clogged downstream in the smaller tubing. Attach the filter to the male hose fitting and begin laying out the ½-inch black PVC along your garden beds. This hosing will feed into the small drip hoses if you choose that style.
3. Some people use an arch over their beds. But I opted for a low-profile design. Attach the tubing to the garden bed sides with bolts and brackets.
4. Lastly, connect and lay out your watering design. The garden drip or spray system is highly customizable and depends on your garden layout and plant placement. Follow the kit’s easy steps to connect each of the components for your hose formation.

Note that I found the small tube drip system didn’t adequately cover everything we had planted, so we switched to spray connectors using a larger ½-inch irrigation tube within the kit. Both could be good options depending on your setup.

Part 3: Electrical setup

Solar Panel

1. Start by mounting the solar panel. Choose a location for your solar panel that receives adequate sunlight.
2. Before attaching, measure out some red and black electrical wire for the distance from the panel to the mechanical box (assuming the panel will be mounted more than 2 feet from the box). Use waterproof heat shrink wire connectors to connect the panel wire to the new long wires.
3. You can find cheap and easy mounting kits on Amazon if you are attaching directly to the roof. Add the mounting brackets to the panel and then screw them onto the roof.
4. If possible, hide or protect the wires along the path back to the mechanical box. I was able to tuck them behind the corner paneling.

Internal Wiring

1. Next, measure and cut out about 6 inches of black and red wires to attach to the battery terminals. Strip the ends. Crimp attach an F2 spade wire terminal to the end of each wire. Attach each wire to the battery with the connector (red-to-red, black-to-black).
2. Connect an in-line fuse off of the red wire (approximately 7.5 amp).
3. Now attach these battery wires to the solar controller. This should be the middle 2 terminals indicated with a battery icon if you are using the same controller.
4. If using a remote, measure and cut out 2 more red and black wires about 6-12 inches. Strip the ends of each. Attach these wires to the DC Input on the remote receiver. The opposite ends of these wires will go to the Load on the solar controller (indicated with a light bulb icon).
5. Next, connect the pump to the remote receiver. If the pump wires are too short, consider attaching another 4-6 inches with waterproof heat shrink wire connectors. Connect the pump wires to the DC Output of the remote receiver.
6. Lastly, connect the two solar panel wires to the solar controller on the left side with the panel indicators.

Solar Controller

When viewing the solar controller screen, you should see panel figures pointing toward the battery. This indicates that it is charging. You should also see a light bulb picture, showing that the load is connected (the pump). Here are a few pics.

Testing & Maintenance

This system is pretty set-it-and-forget-it. However, as with any mechanical system, you’ll need to do some maintenance to help with longevity and efficiency. Here are some tips on how to keep your system functioning optimally.

First, test the system. Turn on the pump and check to see that water is flowing from the rain barrel to the garden beds with enough pressure. You can adjust the flow rate and spray height to make sure that the water is reaching all of the spots you’d like them to reach. Make sure there are no leaks and that the hoses are not kinked or tangled.

Next you can adjust the settings—if necessary. The water pump and irrigation kit may have settings that you can adjust based on your needs. Check the manufacturer’s instructions to see if there are any settings related to flow rate, pressure, or energy use. Adjust these settings as needed to get the most out of your system.

Finally, consider maintenance. I recommend regularly inspecting the rain barrel, the pump, and the hoses for signs of damage. This is pretty easy to knock out whenever you’re filling your water can or doing regular garden stuff.

Always make sure to clean the filter or screen at the top of the barrel. You don’t want that stuff getting in the barrel and clogging things up. If any debris or sediment accumulates in the barrel or hoses, clean that out. Check the battery connections and the solar panel for any blockage or damage that may affect performance.

You also might need to perform some seasonal maintenance depending on your climate. For example, draining and cleaning the rain barrel before winter to prevent freezing or removing the solar panel during heavy snowfall. We have four seasons where we are, so that’s definitely something we’ll need to do.

Troubleshooting issues

About 1 or 2 months after project completion, I ran into some battery issues. The system would only run for about 3 minutes and then shut off. I began isolating every variable: swapping batteries, reconnecting every wire, by-passing the solar controller, removing the remote control, etc.

Eventually I found that—at least this is my leading theory—the solar controller wasn’t that great. And as a result it allowed the battery to lose all its charge. I upgraded the solar controller from the cheapest one I found on Amazon to a more reputable brand with Renogy. I would highly recommend using this controller for your system—I haven’t run into any further issues since swapping.

Daisy chaining our barrels

As I mentioned in the beginning of this tutorial, this was my first rain barrel system. So I had no idea how quickly they actually filled up or how fast you can go through your supply. So we decided to expand!

My wife ordered two more barrels, and I was off to Lowe’s to peruse the plumbing aisle. What you’ll see below is an amalgamation of pieces (e.g., ½ lengths, some L and T joints, etc.). We connected the barrels together at the bottom so that they all fill bottom up from one barrel.

I also attached a nifty sight gauge from Texas Organic Gardening. I dropped a small neon foam piece that floats on top so I can easily see out the kitchen window where the water level is on all three barrels. (Note that in the first two photos below, the filter is not on the system because it’s winter and we aren’t using the system. The other photos are from last summer.)

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