Homeowners ask me about irrigation all the time — "How many zones do I need?" and "What will the system cost?" Here's a simple way to think about both.
If you're trying to size up a system or get a quick sense of cost, start by counting zones. A zone is one section of your yard watered by a single valve. We'll stick to spray systems here and set drip and micro-spray aside to keep it simple. I'm not a big fan of drip: the lines clog, the exposed tubing wears out, and because water only reaches a small area, groundcover doesn't fill in as fully as it does with overhead sprays. Modern low-volume pop-up sprays are more reliable and use little water.
For spray systems, the number of zones tells you roughly what you'll pay. On a typical single-family lot, think in terms of big areas and small areas. Small bed areas are usually watered by small pop-up heads (the Rain Bird 1800 is a common one). Big lawns or beds get rotor heads. A pop-up sprays about 12 feet; a rotor reaches about 40 feet.
A quick way to count zones: picture pop-ups spaced about 12 feet apart and rotors about 40 feet apart, then count the heads. You'll generally get 8 to 12 pop-ups or 6 to 8 rotors per zone at normal household water pressure (around 60 psi). That varies with pipe size, the length of the runs, and the slope of your lot, but this is a ballpark. Count the point of connection — where the system ties into your water meter, usually a backflow preventer, a check valve, the main line to the first valve, and maybe a rain sensor — plus the controller as one more zone for cost purposes.
Figure roughly $1,000 to $1,500 per zone, installed. Add it up: a three-zone system runs about $3,000 to $4,500 installed.
Yes, naysayers will say "What about PSI? Feet of head? Pipe size?" Forget all that. We're just offering up quick numbers here. If you want every calculation done, be my guest.
Finally, take a little time to learn about the types of heads, timers, and rain sensors. Look for the latest water-saving products, from wireless rain sensors to modular controllers. Manufacturer catalogs are worth ordering — Hunter, Rain Bird, and Toro all have them — and ask whether they have simple brochures.
Here are some links:
http://www.hunterindustries.com/
http://www.toro.com/en-us/irrigation/pages/default.aspx
Happy watering!
