As we design, install, revise and repair dozens of irrigation systems annually, I am often asked by potential clients about irrigation. “How many zones do I need” or “What will the system cost” are among many of the questions asked.
If you ever have trouble determining irrigation needs or want a quick estimate, here is a simple way to determine the number of valves and your client’s corresponding investment for installation.
Let’s ignore drip and micropspray layouts at this point in order to simplify. (See my past DonD - ‘Drip is a Drag’ post for a discussion of drip irrigation).
We are talking about spray zones here. If you know the number of irrigation zones/valves, you can get a rough approximation of retail installed pricing. So, on a traditional single-family residential lot, how many zones do you need for any given area?
First, think in terms of big vs. small areas. Small be areas are generally served by small pop-ups (think Rainbird 1800’s). Large lawn or bed areas might be served by rotor type heads. Pop-up spray heads may have a spray radius of approximately 12 feet, rotors approximately 40 feet.
(Image from S&S Sprinklers)
A simple way to determine valve/zones is to place pop-ups at about 12 feet on center, rotors – 40 ft on center and…simply count heads. You will get 8 to 12 pop-ups or 6 to 8 rotors per zone with average residential 60psi water pressure. This of course varies with corresponding pipe size, length and topography, etc. but we are really generalizing here.
Treat the point of connection (POC) and clock assembly as an additional “zone” with regard to cost. Starting at the water meter, the POC is typically a backflow preventer, check valve, the mainline run to the first valve and perhaps a rain sensor.
Consider $800-1500+ per zone installed…
Voila! Add it all up. a 3 zone system? ….$2400 to $4500 installed. That’s the irrigation.
Yes, naysayers will say “What about PSI?, feet-of-head? Pipe size? Yada-yada. Forget all that. We are just offering up quick numbers here. If you have to have all the calculations figured out, be my guest. But I would pre-qualify my client first by making sure that they can really invest in an irrigation system.
Finally, be sure that you can “talk technology” with your client. You should be versed in the latest water saving products, from wireless rain sensors to modular clock technology. Be sure to order some manufacturer’s catalogs and ask if they can provide simple brochures. They are typically free and you can offer them as a handout to your clients….hey – you ARE professional!
Here are some links:
http://www.hunterindustries.com/
http://www.toro.com/en-us/irrigation/pages/default.aspx
Best to ya –
Alan Burke, asla
Landscape architect
Classic Nursery & Landscape Company
alan@classicnursery.com
