So, you live in a townhouse with a small front lawn. It never seems to get the water it needs to "keep up with the Jones who are retired and have a perfect lawn". And you have an erosion problem because your gutters collect water from all the roofs around you. Well, that is what drove me to this project.
I knew I needed to put in a "french drain" to deal with all the water coming down the spout, I also knew that I really needed an automatic sprinkler of some kind to keep the grass going through the hot periods here in Northern Virginia. Those thoughts spun in my brain until I saw this at my local home improvement store- for half price I might add!
Step 1: The Parts
This Deck Storage container was just the right size and shape to make a cistern for a small sprinkler system. I couldn't dig too deep for there were pipes in the same area- this is what kept me from doing a french drain in the first place (that and laziness). This container holds about 50 gallons of water and is made to stay outside year round. It has a lid that seals well. Perfect for making a buried rain barrel that could be the water source for a small sprinkler system.
Step 2: Sprinkler Design
First, let me say that I know this is very small scale. I am blessed (or cursed as some would believe) with a very small front lawn (20' x 20'). I only need 1 zone to water the whole thing. I figured that 8 heads would cover the area.
I'm not going to explain how to install a sprinkler system. If you have ever glued PVC pipe together, you can do it. It is a matter of digging trenches, laying and gluing the PVC pipe, and connecting to a water source. You can also use flexible black pipe. Regardless, the process is the same. Here is a schematic of my system.
Step 3: What It Looks Like
Well, that's it- except for the fine tuning. Which according to my wife will take the next 10 years!
THIS IS WHAT I HAVE LEARNED:
1. If you really want to go "off the grid" water-wise, you will need much larger storage! My sprinklers use about 40 gallons of water in 10 minutes- which is enough to keep the lawn going if it happens every day or other day. But that means that I need it to rain every other day to fill the cistern. N VA can go 10 days between rains, so that means that if I really wanted to be self sufficient, I would need a tank around 400 gallons big.
2. Roof water is dirty! As you can see in the pictures, fine grit from the roof eventually gets in the cistern. I put a filter in the pump and that solved the plugged sprinkler head problem.
3. Pump needs to be bigger! I was going for cheap and got a 1/6 hp pump. It works, but just. To get more pressure (and head), it should probably be a 1/3 hp pump.
BUT- OVERALL IT WORKS VERY WELL. I use house water to fill the tank when it doesn't rain. I do not have it on a timer, although that would be easy to do.
Step 4: CONCLUSIONS
I have decided to connect the sprinkler system to house water. I know, a step backward ecologically speaking, but it will permit it to be automatic and will have a constant source of water and pressure. First, you need an anti-siphon valve. This gets into local plumbing code so be careful. Do what is demanded for your area.
So, what good was the whole project if I am just going to bypass it with house water? Well there are a few ways to go here. First, I could turn the sump pump into a drip irrigation system for all the flowers and bushes my wife is busily planting. Second, I could keep the pump idea, (bigger of course) and come up with a float and control scheme that would fill the cistern with house water IF it was low, but would not be used if the tank was full due to a recent rain. Oh boy! Can you see an Arduino with relays and float sensors? I can!
One other wild idea is to do away with the sump pump and run the house water through a venturi pump that would suck up whatever water is in the cistern. One feature that immediately comes to mind is LIQUID FERTILIZER. So, you see there are many ways to go with this design and I feel it is well worth the effort.
Last but not least- MY EROSION PROBLEM IS COMPLETELY GONE!