It's super easy to build a rainwater collection system at your home. And it's super fun, too.

There are two schools of thought on how to do this: Some people suggest building the entire system from scratch, while others prefer buying parts designed specifically for this purpose, then retrofitting them to fit your custom installation. Either way is okay, but I'd personally recommend buying the proper parts from a reputable company that specializes in rainwater collection systems, that way you know that the products themselves are safe, and that they work well together.

But I digress. Let's get down to business.

Here's what you'll need:

  • A rainwater tank. You can buy these or use a food grade plastic barrel. Just be sure that it's clean and sturdy.
  • A spigot. This fits in the bottom of the tank and lets you pour the collected water into watering pails, pans, pots or whatever else you want. A store-bought tank probably already has one of these installed, but you'll need to add one if you going the homemade route.
  • A rainwater tank stand. You don't want your rainwater tank sitting flat on the ground for a variety of reasons, but primarily because it will make it difficult to pour out the water (the spigot should be towards the bottom to ensure proper gravity feed).
  • A downspout connection. This is how you'll be connecting your rain gutters on your roof to your storage tank. If you're handy you can retrofit pieces of downspout, these parts are super cheap at any local hardware store. If not you can either pay somebody to do it, or even buy a flexible hose that looks just like a downspout.
  • A screen filter at the top of your gutter. You don't want leaves and other garbage flowing through the gutters, down the spout and then into your tank, so put a simple piece of metal screen in the downspout opening (don't make this too fine, otherwise it will plug up quick and often).
  • A fine mesh filter at the top of the tank. A fine mesh will trap whatever particles make it past the bigger screen we just talked about.
  • An afternoon to spend working on this project.

How To Assemble A Rainwater Collection System

These are actually really simple, and if you purchased a kit, it probably came with detailed instructions specific to the parts you have - use those if that applies. But if you're putting your own system together, this section is for you.

Here's what we want:

  1. When it rains, the water runs off your roof into your rain gutters.
  2. The gutters divert it to the downspout part of your gutter.
  3. The water travels down the downspout and into a rainwater collection tank.
  4. This water stays there until you decide to use it.
  5. You access the water by turning the facet at the bottom of the tank.
  6. You smile.

Let's start from the bottom up, as I think it's easiest that way.

Place the stand where you want it, preferably near an existing downspout.

This is where your tank will end up sitting, so it's worth thinking about exactly where you want it for aesthetic purposes. But beyond that, you want an area that's flat and level, and probably in the shade so that the sun doesn't heat your water too much (and create an incubator for bacteria in the process). If you dont want to use a store bought stand you can either make one yourself or use cinderblocks.

Install the rainwater storage tank on the stand.

If you bought one, follow the instructions. If you're wining this, just be sure to keep the barrel level. Water is pretty heavy (about eight pounds per gallon), so when this tank fills up, it will become really heavy. So make sure it's level so it doesn't slide off the stand.

Put the fine mesh screen in place inside the tank opening.

This mesh is going to act like a tiny "final filter" and you'll want it in place before hooking up the downspout to the tank. Speaking of which, let's move on.

Connect the downspout to the rainwater tank.

I'll leave it up to you how you do this, because by now you've probably already guessed that if you're not buying a pre-made system and are doing this one your own, you're the one who knows your plans, not me. I do recommend installing this on the side of the tank, but as near the bottom as possible.

Install the spigot, if applicable.

If you haven't already done so, now's a good time to make sure that you have a way to actually get that water out of the tank once it's been collected. And it's easier to take care of this now than to wait until the tank is full and heavy. If you really want to you can do this step earlier, however I like it now because you can ensure that the facet goes exactly where you want, now that the tank is up and mounted.

Check for leaks.

Now that everything is up and running, take a few minutes and run some water through your gutters with a garden hose to make sure your rainwater collection system is running smoothly, and that there aren't any leaks. It's not uncommon for water to leak out of the joints, so keep an eye on them. You can always use some waterproof compound (like silicon or caulking) to fix up any leaks that do manifest. Just be sure to wipe the area down before you apply it so that it sticks properly, and to use non-toxic stuff whenever possible. The nice thing is that home rainwater collection systems like these aren't pressurized, so you won't have to worry about parts bursting under pressure; for that same reason a little trickle leak isn't going to make the whole system fail, so if you don't want to worry about a teeny tiny leak when you build a rainwater collection system, then it won't be the end of the world.