Bring your irrigation system up-to-date.
The most practical way to water plants, drip irrigation makes more sense than ever in water-conscious 1991. Also called low-volume or micro-irrigation, drip gets water slowly and directly to the roots, where plants need it.
Today's systems involve both simple and sophisticated components that can be mixed to handle any situation. You can combine low-volume emitters, minisprays, and misters to form a hardworking, waterthrifty system for all your garden needs.
Used in conjunction with a digital automatic controller, such a system offers the greatest flexibility and best control of watering.
These innovations let you provide the right amount of moisture regardless of how steep or irregular your lot. Using drip, you can eliminate runoff and reduce the amount of water lost through evaporation and overspray. Savings can be up to 70 percent.
Drip is well suited to most
types of garden watering
Whether you have a large garden with many kinds of plants that have different water requirements or a small garden with only a few containers and a small planting bed, drip can handle the job.
The drawing on next page shows how to design a complete system to water trees, shrubs, ground covers, flowers, vegetables, and pots.
Drip can easily be used in special planting situations, too. You can use in-line emitters for plants growing between paving, create a multicycle mist system for frequent watering of shallow-rooted plants such as bonsai, make a ring of in-line emitters to water large containers, and run tubing along eaves to supply hanging pots.
of the system
Most drip-irrigation components available today are sturdy and hassle-free. But before you can design a system, you need to know how the components operate.
Start with emitters--and
misters and sprayers
You can choose from a variety of emitters that deliver water through small openings at slow rates--down to 1/2 gallon per hour (gph) or less. Add to these a choice of misters and mini-sprinklers and the option of perforated or porous pipe, and you have great latitude in design.
Three types of emitters
Drip emitters deliver water from main distribution lines to the plants. To find out which ones work best for your terrain and water quality, ask at an irrigation supply store.
Emitters are best for watering individual plants. Water placement is more precise than with sprays.
Most emitters have barbed ends that snap into 1/2- and 3/8-inch poly tubing, or push into the ends of 1/4-inch microtubing. Some are barbed on both ends, so you can create a chain of in-line emitters on 1/4-inch tubing. Others, like the ones pictured on opposite page, come preinstalled in tubing.
Emitters are color-coded for flow rate; red, green, brown, blue, pink, or black may signify rates of 1/4, 1/2, 1, or 2 gph (not all manufacturers use the same colors to identify the same rates).
Multioutlet emitters have up to 12 outlets per head.
Diaphragm-type emitters (30 to 65 cents each) have an interior diaphragm that open or closes to control flow as pressure changes. They're generally self-flushing and pressure-compensating.
Diaphragm emitters are best for hilly terrain, slopes, and systems using long lines of emitters (don't use if your pressure at the water source is below 5 psi).
Turbulent-flow emitters (30 to 40 cents each) have twisting pathways that reduce pressure by creating turbulence--which also makes them partially pressure-compensating. The wide channels pass debris, so this type is less likely to clog--especially useful if water quality is poor.
Vortex-type emitters (about 30 cents each) spin water in interior chambers to lower pressure where the water exits. Water high in calcium tends to clog them.
These spread water over a wider area but still operate at low-flow rates and low pressure. Insert into tubing, or run off microtubing.
Use for closely spaced ground covers, flowers, and vegetables. As plants grow taller, they may block the spray, but you can rearrange the sprayer or add new ones so all plants get water.
All three types come in different flow rates. Higher water pressure increases the flow and gives wider coverage. Cost is 40 cents to $1.50; stakes cost 35 to 70 cents.
Misters deliver a very fine spray. They're commonly used for ferns and other plants that need high humidity and frequent waterings.
Minisprays come in various spray patterns (30[degrees]-30[degrees] or 40[degrees]-40[degrees] for strips; also 90[degrees], 180[degrees], 300[degrees], 360[degrees]), so they can be used in tight or irregular spaces.
Mini-sprinklers or spinners emit larger droplets that are less affected by wind. Their wide full-circle pattern--from 10 to 30 feet--is useful for large areas.
When you need to water a row of plants, pipe that emits a continuous band of water is a quick and easy solution since you don't need to install emitters. All types should be used with a pressure regulator and filter; the porous kind works best at 5 to 10 psi.
Preinstalled in-line emitters, set every 12 inches, give a continuous band of water. This drip-line tubing is sturdy, clog-resistant, and generally trouble-free. Cost: $30 to $35 per 100-foot roll.
Perforated pipe is often laser-drilled. Choose it for flower and vegetable beds but not for permanent installation, because the holes have a tendency to clog. Cost: about 20 cents per foot.
Porous pipe (ooze tubing) is best for underground installations, as in a vegetable bed, where the tubing stays moist. If the pipe dries out between watering cycles, calcium may build up inside and clog the pores. Cost: $30 to $45 per 100-foot roll.
Five basic components
and one option
Automatic controller. Heart of the system, this unit is also called a timer.
For all but the smallest systems, multiprogram automatic controllers are the most versatile and efficient way to water. If you use two or more separate valves, you can water on different schedules.
Controllers that can be scheduled in hours, rather than just minutes, are the most flexible, since they run long enough to deep-water trees and shrubs. A less-expensive option is a controller that can repeat its cycle several times during the day. Multiprogram controllers cost $50 to more than $1,000.
Valves. All systems need an on-off valve combined with an antisiphon backflow preventer. For help in choosing a suitable kind, call your water department.
For small systems, look for valves designed for low-flow shutoff (1/2 gpm or lower). Valves cost $20 to $70.
Filters. Most household water is clean, but sediments can get into the line during flushing of city water pipes or from old galvanized pipes in your house.
That's why your drip system needs a good-quality 150- to 200-mesh flushable Y-filter--one that uses fiberglass or stainless steel screens to filter out sediment that might clog the emitters. A standard-size Y-filter costs $13 to $26.
Pressure regulators. Most low-volume systems are designed to run best between 20 and 30 psi. But household lines generally range from 50 to 100 psi, with some areas of the West up to 300 psi.
To compensate, you need a pressure regulator, usually one for each main line. Preset for 20 to 30 psi, it reduces the pressure to a rate that won't blow the system. Plastic regulators cost $6 to $10.
Tubing. The standard way to distribute water is through 1/2- or 3/8-inch poly tubing. Flexible and easy to cut, it's connected without glue.
Both inside and outside diameters of poly tubing can vary widely. Keep a sample of your tubing in case you need to buy more later.
Use 1/4-inch microtubing (spaghetti) to connect minisprays and mini-sprinklers to the distribution lines.
In the past, microtubing was used extensively with emitters to supply water to individual plants in the ground. But that makes the system much more fragile, because microtubing is easily knocked away by rakes, animals, and children.
Microtubing is still favored to distribute water to containers and hanging baskets on decks and patios because it's easier to conceal than larger tubing.
Fertilizer injector. Spreading fertilizer over the soil is not an effective way to feed plants that are watered by a drip system. A fertilizer injector puts it directly into the system. Cost is $20 to $120.
Where to buy your
The best places are irrigation supply stores that specialize in low-volume equipment (look in the yellow pages under Irrigation Systems & Equipment or Sprinklers--Garden & Lawn).
It's wise to buy all the materials from the same supplier; you'll get fittings, tubing, and emission devices that work together.
Designing the system
Group plants on separate valves according to water needs and root depths. If possible, place trees, shrubs, flowers, vegetables, and containers on different lines, so that you can schedule watering to suit their needs. (If you're putting out new plants, don't place a thirsty azalea right next to an unthirsty ceanothus.)
To decide on the correct gallonage and number of emitters for each plant, you need to know your soil and plant types. The goal is to wet at least 60 percent of the root zone. The chart on the page before last offers guidelines.
In general, use higher-gph emitters for trees and plants in sandy soil, lower ones for shallow-rooted plants and in clay soil. Also, space drippers closer together for shallow-rooted plants.
For more information on how to plan, design, and put together a system, you can order a reprint of the July 1988 Sunset article "Drip." Send $2 for each reprint to Drip Reprint, Sunset Magazine, 80 Willow Rd., Menlo Park, Calif. 94025.
Converting your old sprinklers to drip
Why would you want to convert an existing sprinkler system to drip irrigation? There are several reasons.
Better water distribution. As plants mature, branches may have grown into the spray pattern, disrupting application; some roots may stay dry while others get soaked. With drip, everything gets watered more evenly.
Drip also allows more flexibility, enabling you to give trees and shrubs the amount of water they need.
Slower, more precise application. Drip emitters come in different application rates, which can be mixed to meet the needs of specific plants. A drip system can eliminate wasteful runoff, excess weed growth, and sprinklers that overshoot onto buildings and sidewalks.
Drip saves water. Low water supplies and the rising cost of water could be reasons enough to make the switch.
Drip adapts to garden remodels. Converting to drip may be the best solution if you're remodeling only part of your garden (however, it's best to start from scratch for an entire remodel).
The conversion makes use
of existing pipes
First you need to position the filter and pressure regulator, then retrofit one or more risers and cap the rest. After that, it's just like installing drip irrigation from scratch (see preceding section).
Remember, you should convert each valve completely from one system to the other. Drip and regular sprinklers don't operate properly on the same line, with one exception: if you have plants and lawn on the same valve. In this case, you can switch the shrub risers to high-pressure emitters (shown at far right).
To water a solid planting of ground cover or annuals, you can also use mini-sprinklers.
The pieces you'll need are available in irrigation supply and hardware stores.
Where do you put the filter
and pressure regulator?
To convert to drip, the water must be filtered to prevent clogs, and the in-line pressure must be reduced to 20 to 30 psi. In most cases, a filter and pressure regulator are added to the line.
You can install the filter and pressure regulator at any one of the risers that hold sprinklers, or at the valve.
Installing at a riser. Drip lines can run 100 feet in any direction from one sprinkler riser, so you may only need to convert one riser. install a filter and pressure regulator at the riser, as pictured at right. Remove the other heads on the line and cap them with threaded caps.
Keep the filter and pressure regulator aboveground so the filter can be cleaned.
Installing at the valve eliminates the need for more than one filter and pressure regulator if you're converting two or more sprinklers.
The fittings and adapters you'll need will vary according to the system you have. Take a drawing of your valve setup (with measurements) to the store and do a trial assembly of the pieces.
To install them, remove a section of pipe below the antisiphon valve (this is easier to do with PVC than metal). Dig down just beyond where the line makes a 90[degrees] turn toward the sprinklers and unscrew the vertical pipe from the elbow, or cut the pipe, if necessary.
Then remove all the sprinkler heads, choose which ones to adapt, and cap the rest.
To adapt a riser for the drip line, you need a PVC elbow or T that screws onto the riser and a fitting (or two) that will adapt it to a compression fittinf for attaching the drip tubing; glue in the fittings with plastic pipe cement.
High-pressure emitters screw
right onto the riser
These emitters are installed directly onto risers; they are useful when you have clusters of plants around each riser, rather than plants spread out over a distance (this requires too much microtubing, which is easily disrupted).
It's best not to put them on the same line with sprinklers, unless you have no other choice (you need some sprinklers to water a lawn).
Each emitter has 4 to 12 outlets and a built-in pressure regulator and filter. Add more filters only if you water pressure is higher than 100 psi, you irrigate with well water, or you use laser-drilled tubing.
If your system is galvanized pipe rather than PVC, wrap the riser three times with nonstick fluorocarbon tape and hand-tighten the emitter onto it so the plastic doesn't crack; or change to a PVC riser. Attach microtubing (for shrubs and trees) or laser-drilled tubing (for closely spaced plants).
Troubleshooting sprinklers that waste water
Malfunctioning sprinklers can waste huge amounts of water, especially when problems arise on automatic systems that turn on early in the morning. A broken sprinkler or overshooting head may never be noticed, but you'll surely feel the pinch in your water bill.
To make sure your sprinklers are functioning properly, here are some simple steps you can take to check them out.
Once a month during the season, look for broken, clogged, and leaking heads and poor spray patterns. If the sprinklers are exposed to high traffic, car tires, lawn mowers, or other equipment that can knock heads out of adjustment or break them, check them more often.
You can probably identify and fix basic problems that can disrupt a typical garden system by yourself. Many of the repairs can be done with the use of common, inexpensive tools.
Stores that specialize in irrigation equipment carry high-quality replacement parts. But you need to know what kind of sprinklers you have; if you're not sure, take the head to the store with you.
For more difficult repairs, such as a broken pipe or electrical problems on automatic systems, it may be necessary to call in a specialist.
Check the system for
Turn on the system and watch for heads or risers (vertical lengths of pipe below the heads) that have water streaming or gushing out of them. If the head or nozzle feels loose, tighten it.
Replace sprinklers or risers that are bent, broken, or missing. Remove brass sprinklers with a head wrench. (Purchase one that's the same brand as your sprinklers--or buy an adjustable "universal" head wrench.)
Old brass heads are sometimes difficult to remove. For more leverage, slip a pipe over the handle of the head wrench. When you unscrew the head, try not to remove the threaded nipple that sits underground between the head and the water line.
If you sense the nipple is turning when you're unscrewing the head, remove enough soil so you can hold the nipple with pliers or a pipe wrench. If the head has rusted onto the nipple and you can't separate them, replace both parts.
To avoid getting dirt in the irrigation pipe, remove heads carefully. If the surrounding soil is dry, wet it so it doesn't crumble into the hole. Dig out around the head if the soil doesn't hold together or if water from the sprinkler line starts to flood the area.
Bits of soil may still drop inside and clog sprinklers, especially brass heads. If the new head sprays unevenly, flush the line. Since dirt can travel through the pipe, you may also have to flush other brass heads if they get clogged down the line.
To fix a broken riser, unscrew it from the line and replace it (use nonstick fluorocarbon tape for galvanized pipe connections). If the riser broke off inside the water line, leaving a piece that's difficult to get out, use a stub wrench to remove plastic risers, or a screw extractor ("easy out") for galvanized pipe.
Look for clogged or
Since brass sprinklers don't have filters, they tend to clog frequently. Soil, mineral deposits, earwigs, and other insects and debris collect in the slit or holes where water emerges. Several times during the season, check heads for uneven spray patterns while the system is on. Clean slits with a knife.
Flood and stream bubbler heads have small openings that can't be cleared with a knife blade. You may be able to clean flood bubblers by opening the adjusting screw to full flow. Otherwise, unscrew the heads and clean under running water. If plastic heads are spraying erratically, clean the filters inside (unscrew the cap or nozzle) and clear the openings.
With pop-up brass heads, debris can also collect around the wiper seal on the stem. This may prevent the head from sealing; water will then squirt or bubble out from the base (see picture at left) and the spray will be weak. Clean or replace the head.
If this problem develops on several heads near one another, there may be too many sprinklers on the line, or the water pressure may be too low to lift and seal them. Brass heads, which need high water pressure, are especially susceptible. You may have to replace the brass heads with low-pressure plastic heads--or call in an irrigation specialist.
Insect sprinkler patterns
and water distribution
Depending on the time of day your system is on, water pressure will vary and affect distribution from the sprinklers. Check your system at the time you normally use it. While the system is on, look at sprinkler patterns. Make sure the spray from each head isn't blocked by tall grass or plants. Old lawns often gain several inches of height because of thatch buildup. If the head sits so low the spray is blocked, change it to a pop-up if it's a stationary type, or add a riser extension. Also keep grass clipped down from around heads.
Sprinklers in shrubs are often installed too low to spray over mature plants. To improve coverage, add a coupling and a riser.
You get the best coverage when the spray from one head reaches all the way to the adjoining head. If the overlap is poor, brown patches will eventually show up in the lawn, or plants will start drying. Most homeowners try to compensate by running the sprinklers longer than necessary, wasting water.
Pop-up brass and plastic heads usually have a small screw on top to adjust the flow of water; to increase the radius of the spray, use a small (1/8-inch-wide) screwdriver counterclockwise.
If the screw is already fully open, replace the head with one that has a larger radius, as indicated on the head.
When a sprinkler is overshooting an area, reduce the flow of water by turning the screw clockwise. But don't try to reduce the radius by more than 25 percent (from fully open). If necessary, replace the nozzle with a smaller size.
Lawn browning and plant dieback may also occur if the sprinkler head puts out the wrong spray pattern for the area. Patterns range from quarter-circle to full circle, including strip sprays for long, narrow beds. The pattern of the head is identified by letters (H for half, TT for two-thirds) or numbers (1/4, 1/2). Plastic heads may also have score marks on them. For instance, if a quarter-circle sprinkler isn't fully covering the area around it, you can change it to a half-circle (with pop-up brass and plastic sprinklers, you only have to change the nozzle, not replace the entire sprinkler).
After you've repaired the major and minor problems on your system, check the heads along the perimeter of the lawn and planting beds to make sure they're aimed in the right direction. If any of them are spraying off-center, gently turn the heads or nozzles with a head wrench or pliers until they line up.
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|Title Annotation:||Sunset Drought Survival Guide for Home and Garden; includes related articles|
|Date:||May 1, 1991|
|Previous Article:||How to water wisely and well.|
|Next Article:||Gardens that are designed for drought.|