Using rain barrels for drip irrigation when there's no rain.

I've written about rain barrels multiple times in the past.  I think they're great!  I can't think of another resource that's as free and easy to get.  The water literally just falls from the sky.  You just have to catch it.  (The only other thing that might come close is leaves.  They fall to the ground in abundance, but you have to gather, mulch/shred, and pile them in order to make decent compost.)

One of the drawbacks to rain barrels is that you're dependent on the weather.  The frequency and amount of rain you get can be quite sporadic.  The best way to deal with this is to have a sufficiently large storage capacity to provide enough water between rain storms.  I currently have enough rain barrels to store 590 gallons of water, and not all of it is available where I need it.  It isn't nearly enough water for my needs.

I have 4 barrels feeding the drip irrigation system for my raised beds.  I haven't done any rigorous testing or note taking, but I think it takes about 4-5 days to empty them. 

So the obvious question becomes, "How do I continue to water my gardens once the barrels are empty?"

Until a few days ago I was manually turning on the hose and filling the barrel directly connected to the drip irrigation line.  I shut off the valve that connects it to the other barrels (I only wanted to fill one barrel, not four.)  Manually filling the barrel is a nuisance.  I had to keep an eye on it to make sure it didn't overflow. 

I needed a better solution.  Luckily I already had it.  One of my overflow barrels has a float valve in it.  And since we got rid of the ducks I don't need nearly as much water in the back yard.  It just made sense to move the barrel to the front yard.

Overflow rain barrel.

I moved the barrel from the back yard to the front yard.  I attached a Y-valve to the hose bib and used a short piece of hose with female couplings on both ends to connect it to the barrel that was already there (that barrel is connected to 3 barrels on the other side of the house).

I attached the drip irrigation line to the new barrel.

I attached the hose to the float valve on the barrel with PVC fittings.

• 1/2 in. PVC Schedule 40 Pressure 90-Degree S x FPT Elbow
• 1/2 in. Slip x 3/4 in. FHT PVC Fitting
• 1/2 in. PVC pipe.

I actually glued the PVC pipe and fittings together since I have high pressure water going through them.  I generally don't bother since I normally work with low pressure water.

I put the hose on a timer and have it set to come on 4 times a day for 20 minutes each time.  I didn't see the need to keep the water on all the time.  Although I suppose it wouldn't hurt. 

Here's a view inside the barrel.  The water is quite low.

Here's a view of the water filling the barrel.

Here it is full.  The water rose enough to shut off the float valve.

The next time it rains the rest of the barrels will fill.  Then I can simply shut off the hose, open the valves connecting the barrels and irrigate with rain water.