Landscape Sprinkler System Design Tutorial
Well, if you are working through the Sprinkler Design Tutorial, you’re now pretty much finished with your irrigation design. Here’s a few reminders and additional items to consider.
Automatic controllers: For automatic systems you will need a controller (often called a “timer”) with one “station” for each valve. If you have both lawn and shrub areas you should make sure the controller has 2 or more “programs”. Multiple programs are somewhat like having several “timers” in the same controller. This allows you the flexibility to run the lawn and shrub irrigation on different days. Study the different models and features available on various controllers. They range from simple timers to extremely complex computerized units that can monitor all the functions of your entire home! I suggest you take a look at the article on Smart Controllers if you are interested in the latest innovation for saving you time and water.
Isolation valves: It’s a good idea to install a manual shut-off valve at the point where your irrigation system connects to the water supply. I know I already covered this, but not doing it is a big regret that I hear often. An isolation valve allows you to shut down the irrigation for control valve repairs without shutting off the water to your house. You will have to repair a control valve at some time. I recommend using a “ball valve” for the isolation valve, as ball valves are the most reliable and reasonably priced shut off valves. Most inexpensive “Gate valves” will leak.
Wires for valves: For wires going to the automatic valves use wire made specially to be buried. Most people use a special direct burial cable made for irrigation systems. The cable contains 3, or more, separate, 18 gauge wires. On commercial systems the standard wire used is “#14-1 AWG-UF” which is a single strand, direct burial type wire. One white color “common” wire goes from the controller to every valve, and one individual “lead” wire of a color other than white goes to each valve from the controller. Be sure to read the Irrigation Installation Tutorial. Also there is a sketch of typical irrigation system wiring that should help you understand the wiring.
Details: To further help you there is a collection of installation details. These simple sketches will help you figure out how to assemble your irrigation system. These installation detail drawings are normally included as a part of the design drawings for an irrigation system.
Filters: I recommend you install a screen-type water filter upstream of the valves. Drip systems should always have a filter! This helps reduce maintenance problems caused by small bits of sand which are found in almost all water systems. These small sand grains can make the automatic valves malfunction and also clog sprinkler heads over time. A $50.00 filter may seem expensive, but it is a lot cheaper than a $100 valve repair job or replacing a dead lawn. I recommend a “150 mesh screen” in the filter. The filter can be installed underground in a box if you don’t want it visually cluttering up your landscape. On the other hand, it is nice to have it in a more convenient above-ground location for maintenance. Remember, you need to clean the filter screens at least once a year if not more often! For tons more information on filtration see the Irrigation Water Filtration Tutorial.
Cold Winter Precautions: Unless your irrigation system is in an area where it never freezes you should insulate the backflow preventer and any other above ground equipment. Backflow preventers are very expensive, you don’t want an unexpected freeze to catch you off-guard. A few years back that happened here in California and thousands of backflow preventers had to be replaced because the water froze in them and they split open! I usually use foam insulation tape to wrap the backflow preventers and above ground valves, then wrap the insulation with a layer or two of 10mil black plastic tape to protect it. There are also some pretty neat backflow preventer blankets (essentially a big insulated bag), that are made to fit over the backflow preventer like a big coat. They work good, I use them. (I have a small one in my truck that I use to keep cans of soda cool when I’m on the road. It also makes a great pillow!) If the backflow preventer has air vents or a water blow-off outlet it is extremely important that they not be blocked by insulation! There should be instructions that come with your backflow preventer.
Winterization: In areas where freezing weather occurs you need to take precautions to protect your irrigation system from freezing. There is a whole tutorial on winterizing your sprinkler system in areas where it really freezes hard. It covers the various methods used, advantages and disadvantages of each, and what you will need to install as part of your new sprinkler system for each method.
Pumps: Thinking you might need an alternative water source for your sprinklers such as from a pond or lake? Check out the Irrigation Pumping Systems Tutorial.
How much will it cost?
That’s hard to say. I priced out the materials for the little sample irrigation system at the top of this page at $375.00. That included reasonably good quality sprinkler heads, “funny pipe” type risers, Cl 200 PVC pipe, anti-siphon valves, and a very inexpensive $50.00 controller. That comes to about $0.25 per square foot of irrigated area. You may need to add extra for a better backflow preventer and better controller. I would suggest in most cases that you estimate at $0.25 per square foot plus the controller and backflow preventer cost.
Installation generally costs about 1.5 times the cost of the materials. Installation costs can vary wildly, be sure to get 3 bids. If any bid is significantly lower than the others I would be extremely suspicious and use extreme caution before hiring that cheap contractor. Never pay a deposit up front unless you are willing to risk losing that money. If the contractor needs up front money insist that he deliver materials equal to the deposit value to your house prior to payment. Remember if the contractor needs money up front to buy supplies that means the suppliers won’t sell to him on credit. Suppliers sell to almost everyone on 30-day interest free credit, so if they don’t trust him/her to pay them that should be a huge warning to you! The irrigation installation business is very easy and cheap to get started in, and as a result it has a huge number of contractors are under-financed, then under-bid to get work, can’t complete the work, and fail. Understand that property laws in the USA allow the supplier to place a lien on your home for the value of any materials the contractor buys for your sprinkler system, but does not pay for. It does not matter if you paid the contractor already for those materials. The supplier can still make you pay for them again. That is the law. Be smart, protect yourself!!!
Now you’ll probably want to move on to the tutorial on to the Sprinkler System Installation Tutorial. It covers in more detail the various irrigation parts you will use, like sprinkler risers. It also teaches you to “talk sprinklers” (so you can sound like you know more than you do!), helps you make a list of the materials you will need to buy, provides some helpful forms you can print out, explains which tools can make your day or break your back, and a few other tips and tricks! Be sure you read it before you buy anything or start digging!!! (Just when you thought you were finished!)
End of Tutorial
(As you will note, I’ve enlisted some assistance from my family members!)
Written by Jess Stryker, Landscape Architect, unless noted otherwise
- Julie Stryker, the love of my life!
- Nathan Stryker, my son.
- Dan Fahndrich of Farwest Gardens, Inc.
- The many tutorial users who have asked questions and pointed out unclear topics.
- And even a few jerks who have kept me (sorta) humble!!!
HTML Coding and page design:
- Jess Stryker & Nathan Stryker
- NoteTab Pro by Eric G.V. Fookes, www.notetab.com
- Jess Stryker
- Nathan Stryker
- Steve Brinkman
Other individual credits are listed on the pages of the tutorial.