I have a big garden set back from the house that is hard to get a hose to. Because it is mulched with woodchips, it retains moisture after rains pretty well, but I can still use some supplemental water during the dry periods of summer. A rain barrel seemed like the perfect solution, as we have a shed in the back near the garden. Only problem is most of the DIY rain barrel tutorials rely on gutters to channel rainwater, and my shed is gutterless. So what to do? I didn't want the hassle of installing gutters just to have a rain barrel, and I also didn't want to spend a lot. This system cost less than $20 in materials and I installed it in less than an hour. After one aprox. 3 hr rain, I had a full 30gal barrel of water. Virtually fully sealed and no mosquitoes or clogs. Here's how I did it.
Step 1: No Gutters...no Problem!
I didn't want the hassle of installing gutters just to have a rain barrel, and I also didn't want to spend a lot. You can use as big or small a tarp you like. I just used a 4'x6' because that's what I had lying around. But the bigger the surface area or your tarp or structure roof, obviously the more water you can channel. One of the advantages of this system too is it doesn't have to be near the house, which may be unsightly and also far from where you want the water. In the next step I will describe how to attach the tarp. In my case, I attached it to the side of the shed.
Step 2: Secure Tarp
I used a 4'x6' waterproof nylon tarp that I had lying around. The bigger the tarp the more rain you will channel into your barrel. It should have grommets on the corners and in the middle of the sides (8 total). You may have to get creative with how you string it.
I decided to secure mine longways along the wall of the shed, just under the roof overhang. I used a couple eyelets screwed into the joists and ziptied the two corners to the eyelets, one on either side. I then strung up the other two corners at equal height. One side I strung to a nearby tree. On the other side, since there was no tree nearby, I fashioned a pole using a shovel handle that was secured to the wall with zipties and and eyelet. This is not necessary if you have something like a tree or structure to string it to on either side. You basically want something that resembles a sun shade on an RV.
Step 3: Created the V-shaped Water Channel
When you have your tarp secured and just about level with the ground, secure your rain barrel or trashcan underneath it. Tie a braided string from the center grommet on one of the long sides of the tarp. The string should be about five feet long or so. You want to weight the string down a little to create a 'V' in the tarp for the water to channel down (I tied mine to a 5lb weight on the inside of the trashcan).
What happens is when it rains and water collects on the tarp, it funnels to the point where the grommet is and through capillary action follows the path of the string. This will be described in the next step, but essentially you want the water to channel along the string, through a funnel secured in the removable top of the trashcan or rain barrel, and into the container.
Step 4: Funneling the Water
I got a funnel from the Dollar Store (3 for a dollar) and used the largest one. I drilled a 1/2" or so hole in the middle of the lid, popped the funnel in, and put a bead of expanding (Gorilla) glue around where the funnel meets the lid.
Once it dried, I threaded the string through the hole and tied it with a half-hitch around the 5lb weight I had lying around in the bottom of the trashcan. This serves two purposes. It keeps the tarp weighed down and the V in tact, and also keeps the trashcan anchored when there is no water in it so it doesn't blow away.
Step 5: How It Works
Although my 30gal trashcan is elevated on a couple cinder blocks, it can just as easily sit on the ground. I chose not to mess with a spigot and hose and instead lift the lid and dip a 5 gallon bucket inside. It fills quickly and I just carry it to water my plants.
The funnel/lid setup keeps mosquitoes out for the most part, since the hole is so small, and also keeps debris from entering since it's fully sealed. It's amazing how capillary action works. I went out in a rainstorm and watched the system work...the rain literally just follows the string and dumps into the container. In a recent 2-3hr rain storm, the trashcan was full at the end of it.
Step 6: No Limit to How Much Water You Can Store
It's not a bad idea to have an overflow tube for when the container fills up. You can drill a 1/2" hold on the side at the top of the trashcan and Gorilla Glue some tubing in the hole. When it gets near the top, the water will drain out of the tube and go where you direct it. You can even feed it into another trashcan or rain barrel and double, triple, quadruple, whatever your storage. I find I don't need much more than 30gal at a time, and we have relatively frequent rains in our area. But the trashcan only cost $12, so I may buy a few more and link them together with tubing.
Step 7: That's It!
Really happy with how this has worked out. I don't have to run a hose to the garden; it's a versatile setup that can be strung up in a number of ways; I can have the water source near the garden (rather than having to be near the house); no mosquitoes, sealed from clogs; and really cheap to construct.
I hope you enjoyed this tutorial. Happy gardening!