Irrigation System

Last summer, we installed an irrigation system for our grass and garden.

Before we installed the system, we were using a series of hoses, splitters, and sprinklers.

The first thing we did was make a plan of what we wanted in an irrigation system - what needed watering.  I wanted another hose attachment, a drip irrigation system for my garden, and to water my weeds (aka a lawn).

The next logical thing I should have done was to test the pressure and flow of my plumbing system.  The pressure and flow of my plumbing system ultimately dictates how many sprinkler heads I can have on at the same time.  Each set of sprinkler heads is controlled by an electronic valve that is wired to a fancy timer.

Here are a few good sites for planning a sprinkler system:

http://www.sprinklerwarehouse.com/DIY-Determine-Pressure-and-Flow-s/6671.htm

http://www.dummies.com/how-to/content/planning-your-lawn-irrigation-system.html

http://orbit.homedepot.com/sprinkler_design

I had the advantage of already having a pipe going out of my basement to an existing set of sprinklers in my front yard.  Whoever lived in my house before me took EVERYTHING when they moved out, including all of the sprinkler heads for my front yard.  The existing setup also lacked two important things: a backflow preventer, to stop water in the irrigation pipes from flowing back into my system, and an automatic valve, so that I do not have to turn the water on and off manually.

A view of my main water line and the irrigation connection (where the green-handled valve is).  The installer of the irrigation system had the foresight to install a drain on the irrigation line.

I left a space for a backflow preventer.

I installed two boxes to house my valves - one box in the front yard and one in the back.  One valve takes care of all of the sprinklers in my front yard.  The other valve irrigates 1/2 of my back yard. The middle pipe in this muddy mess of a picture has a manual valve (red) that leads to the back box.  Note the extra space I have for another valve.

The back box is a clustered mess.  There are three valves, one for 1/2 of my back yard and the other two are for my drip irrigation system.  There is also a continuation of the irrigation line that goes to an outside spigot.

One of my drip heads (a filter, pressure regulator, and adapter) and my extra spigot.

Here is a close-up of my other drip head.  I has a pressure reducer (red cap) and a filter (big black thing) that goes to the main drip line.  From the main drip line are many smaller drip tubes with special drip attachments that dictate how water is delivered to the plants.

One of the smaller drip lines goes to a hanging basket.  Unfortunately, I set up the drip line too late for the flowers that were in there.

All of the boxes and sprinkler heads are connected by a series of  underground PVC pipes.  To get these pipes underground, I rented a trencher from Home Depot.  I bought thicker pipes to make my effort worthwhile.  I strongly advise anyone who is planning on using a trencher to call 811 first (at least a couple weeks in advance).  I also laid wire to control the electronic valves in these trenches.  

That wire leads to an irrigation control timer, which can be set to turn on the different valves at different times.

A schematic of my resulting irrigation system.

Recommendations:

1. Make liberal use of quick disconnect PVC connectors to make valve maintenance easier.  They add bulk to the valve box, but they are really handy when working on an irrigation system.
2. Always leave room for expansion in your valve box, valve assembly, and on your timer system. Bury extra valve cable when you install your lines so you don't have to dig new trenches to add valves.
3. When trenching for sprinkler lines, make best use of the trencher by also trenching drainage lines, so that your yard can drain effectively.  Create a deeper trench in the downhill direction of your yard to increase the gradient of flow.
4. Use flexible risers that come off of the side of the main pipe. If you hit your sprinkler head on a non-flexible riser, you could snap your sprinkler line.  
5. Give yourself a little extra room with your flexible riser pipe so you can accommodate for settling and ground movement.
6. Install self-draining valves for each zone, so that most of the water leaves the pipes after the zone is done being used.