Delete the Nuts: Rain barrels -- Plumbing them all together.

My house came with a single rain barrel. I used it frequently last year to water the garden. I ran into two issues.

It was frequently empty.
It is located at the back corner of house far from where it was usually needed.

So I added more barrels, six of them (see here and here). This solves problem #2. I now have barrels all over the place. It doesn't solve problem #1. They can still end up empty.

The solution? Plumb them all together. This does several things. Because of the layout of my house, the rain barrels are under various lengths of gutter. That means they fill at different rates. By plumbing them together, a faster filling barrel can move excess water to a slower filling barrel before overflowing. This also allows me to drain multiple barrels at the same time. Or I can drain them independently and refill them from the other barrels.

That said, I'm not using pumps of any kind. I'm entirely dependent on gravity and that law of nature, "water always seeks its own level."

I put 2-way shut offs on all of my barrels. This allows me to plumb them together with irrigation tubing and still get water from them. Why irrigation tubing? It's cheap. I cat get 100 ft. of it for ~$11. And it's made for moving water! It is only 1/2" in diameter, so I'm limited as to how fast I can move water. PVC pipe would probably be nicer, but it'd be more expensive, and I'd have to fit, cut, and glue it all together. With irrigation tubing you just unroll and pull.

Irrigation tubing is great, but connecting to the garden hose fittings is somewhat of a pain. I've tried several options. I can't really say that one is better than another.

This barrel is off of one corner of my deck. For this barrel I used female pipe thread (FPT) to female hose thread (FHT) PVC swivel fitting. The FHT side attached to the barrel and into the FPT side I attached a 3/4" MPT barb adapter. The irrigation tubing attached to the barb. I've never had an issue with leaks with this setup.

The connections on this barrel are similar to the one above. I used another FPT to FHT adapter. Only this time I used an elbow barbed adapter. I did have issues with the irrigation tubing leaking on this barb. I don't know if I got a bad barb or what, but a hose clamp fixed it.

Eventually I found an item made just for attaching irrigation tubing to a hose bib. It works. I have had issues with them though. First of all, it's difficult to get the tubing inserted far enough to make a tight fit. The first time I tried one of these it leaked. Then I found another issue. These things are made so that once the tubing goes on, it doesn't come off. I broke the leaking one apart to find out how it worked. I don't remember the internal workings exactly, but I do remember thinking that the tubing would never come back out once inserted. The second one I used cracked near the top, and leaked as well. That may have been user error. It had it attached on some nights when it got down below freezing. Or maybe I dropped it on the stone under the barrel. Who knows. The third one seems to be working for now.

These are the barrels at the front of the house. I've attached the same FHT to tubing adapter as I used on the barrel above. I've had no issues with it. I ran tubing along the house and tied it to the barrels at the back of the house. I generally keep this valve closed. These barrels sit higher and I don't want the water in them to overflow the backyard barrels. When the backyard barrels get low I can refill them from these barrels.