Eel River at flood stage, December, 2002
Watching the Eel River at flood stage when over 180,000 ft³ of water (well over a million gallons) was passing by every second.
During the dry season you can walk across it without getting your knees wet. Awesome place to live and raise a family.

Part 3 of Saving Your Rainwater

Materials for the Collection Part of the Rainbarrel System

Most single rain barrels have a hole in the top to put the water in and a faucet near the bottom to take the water out. We're going to instead build a manifold which will connect the barrels and will move the rain water into and out of the system. It is made using PVC pipe and fills and empties the barrels from the bottom. It has water in it all the time.

We built it in the form of an upside-down letter T. The 2" diameter vertical part collects the water from the gutter. Why such a fat pipe? It also acts as a reservoir when we draw the water. The 1" horizontal part at the bottom distributes the flow evenly among the six barrels. It has the faucet on one end (could be on both) to draw water from the system. Everything is slip fit PVC except for where the faucet and flex pipes connect to the manifold. There is some gluing involved. Here's what it looks like finished, keep reading for the step-by-step instructions and pictures.

We're done! This shows the barrels in place and all the plumbing hooked upEnlarge image

We could have asked the local gutter installer to recycle some parts to us, but a deadline meant we had to buy them instead, along with some of the plumbing stuff. We had some of these parts already but we still spent about $140 total for this system. Most of the following parts came from Ace Hardware, and the flex pipes were available at a plumbing store.

From the rooftop down (2010 prices):

Two important construction details...

1. The barrels have to be at roughly the same level at the top. It doesn't matter if they are of different heights and widths and capacities or even if one is across the yard, but all the tops will have to be held at the same horizontal level for this to work. The water level in all of the interconnected containers will match the water level in the lowest one. Knowing this, you could easily add another batch of storage barrels nearby with only a single pipe connecting them to this system. We're planning on doing that.
2. Each barrel's bulkhead fitting should be above the horizontal part of the manifold to allow each barrel to fully drain. How much higher is not critical, it just needs to be higher.

...and two important safety details:

1. Full barrels are heavy, nearly 500 pounds each, so build a sturdy and wide platform if you raise them off the ground. Two feet is enough for filling buckets. We sometimes hook a 75-foot hose to this faucet but the water just dribbles out the end.
2. This water is for your soil, not for you. Don't drink it, not even a taste.

Construction Details and Pictures

The shed has a thin metal wall and we used an assortment of nuts, bolts and washers to attach the collection system to it.


Installing the gutterEnlarge image

After installing its mounting brackets, the gutter snapped into place. It is important that the drop be at the lowest part of the gutter, but it does not have to be in the middle as shown here. The smallest pipe used in this system is the half-inch flex pipe, so we laid quarter-inch hardware cloth over the drop opening inside the gutter to catch the big trash.


Shows downspout with the overflow teeEnlarge image

This is the 2" drop pipe and that top tee is the overflow. One barrel and its support had to be set in place temporarily to determine where this tee would be placed because we wanted this opening to be just below the tops of the barrels. We're going to put a 1" elbow into this overflow without gluing it. Swiveling it will allow us to fine-tune the water height in the barrels.

Do we really need this overflow? No, we could just let the water run through and out of the vented tops of the barrels. But we put this in because this roof collects foreign matter. This overflow will help keep the extra water and most of its trash out of the system, and we will have less maintenance.

North Coast California's climate is that of a temperate rain forest (the giant redwood trees live here). This half of the roof collects enough rain to fill forty of these rain barrels during the November through March rainy season, which brings us three to four feet of precipitation. That's a lot of rain, as you can see from the picture at the top of this page!

So if we had all this extra water, why did we stretch the gutter for the entire width of the shed? The night-time humidity during the dry season provides moisture which collects on the metal roof. This adds a few gallons when we need it the most, and that's when that gutter needs to be as wide as possible. We could even add a gutter to the other side of the shed's roof and plumb that into the system when we need it.


Straps and wood strips hold the pipe to the shed wallEnlarge image

Wood strips and metal straps hold the manifold to the wall. Just plain straps would work, too. How did we know where to put the horizontal part of the pipe? It's just below the bulkhead fittings so each barrel will completely drain to the bulkhead fitting.


Barrel framework in place and one barrel is connectedEnlarge image

The plumbing is done and the first barrel is in place. We made sure that all of the fittings from the overflow tee to the bulkhead fittings on the bottoms of the barrels are watertight. The water level in the vertical drop pipe will always be the same height as the water in the barrels, and a leaky fitting would cause water loss. We did change the faucet that you see on the end of the manifold pipe after realizing that its inside diameter restricted the flow.  We replaced it with a full-port ball valve.


Flex pipes hook the barrel;s to the manifoldEnlarge image

Each barrel has a flex pipe to connect to the horizontal part of the manifold. Water flows through it in either direction depending on the difference of the water level in the barrels and the vertical part of the manifold. Why is there insulation on the horizontal pipe? Several times during the early spring this area may enjoy a brief morning freeze, and the insulation will help keep the plastic pipe from cracking. The non-rigid flex pipe does not need insulation, nor does the vertical pipe. Does it freeze hard where you live? You may then need to drain this for the winter.

Why don't we just connect the barrels to each other, pour the water in at one end and put the faucet on the other? We could, but then all the water would have to pass through every barrel and every connection, limiting the flow, and if one plugged up, we could be in serious trouble. 

Why are we using flex pipe? The ground often shakes here, which could cause rigid pipe to break; but more importantly, any barrel (even a full one) can be disconnected from the system by implementing a cap and a plug. There's just enough room to squeeze between the shed wall and the barrels to do simple maintenance work, and it's easy to work with because there's not a lot of water pressure in this system.


We're done! This shows the barrels in place and all the plumbing hooked upEnlarge image

We're done! We've checked for leaks, covered the bung holes to keep out the mosquitoes and made sure each barrel is vented at the top. This system is at the higher end of the yard and is almost two feet off the ground with cinder block support. Note that the overflow tee now has an extension to direct excess water to the existing french drain located under the barrels.

Water Seeks Its Own Level

So how does this work? Rain water is collected in the gutter and drops down that vertical pipe. When it reaches the bottom it flows into the horizontal pipe, then into the flex pipes and into the barrels. More rain increases the water level in the vertical pipe and the water flows into the barrels to match its level. When this water level reaches the overflow tee the barrels will be nearly full and all additional water and much of the trash then exits through the overflow tee.

When you open the faucet, the manifold's water level drops and the water flows from the barrels in an attempt to refill it. Water will continue to flow out of the faucet until the barrels are emptied. The next rain event replenishes the system automatically.

There are no moving parts and nothing to keep track of. We like the low maintenance and haven't even needed to clean it. A few times a small glob of algae has come out of the faucet. It would make sense to completely drain the system at the beginning of the rains to help flush it, but we've only remembered to do that twice in the last five years.

Send mail if you have any questions.

What's with the overflow tee? Do I really need that?
Even though the system is passive, it receives rainwater while it is filling up and diverts it after it is full. Without it, each rain would introduce more water and more dirt into the system.

Can I use this to run my lawn sprinkler?
No, this is best used to fill a bucket since there is very little pressure in the system. If you connect a hose, water coming out of the system will never flow higher than the water level in the barrels. It will also flow slowly due to the friction inside the hose.

What if my downspout collects rainwater from a much larger roof area? Will a heavy downpour cause rainwater to back up into the gutter?
A larger collection area would require a larger overflow tee. Use a 2" x 2" x 2" tee or even switch to a 3" vertical manifold and use a 3" tee. Direct the overflow water away from the building foundation.

Could I use 3/4" flex pipe and bulkhead fittings? Or bigger pipes and square water tanks?
Certainly. Pipe and barrel sizes and shapes make no difference, and it isn't even that important where the water storage units are located. The critical take-away here is that, since they are all connected at the bottom, the highest water level in each barrel or container has to match the level of the overflow tee. Also, the pipe with the faucet has to be below the containers or barrels so they will all drain properly. Everything else is negotiable.

Everything else is negotiable? Are you sure this will work?
Works just like the Grange Hall's 40-cup coffee urn that has the coffee level tube above the spigot. When you refill your cup the coffee level in that tube (the manifold) drops down and the coffee in the urn (the barrel) attempts to refill it. Coffee urns are not usually refilled through that tube, but they could be.