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Changing from sprinklers to drip.

Changing from sprinklers to drip

Why would you want to convert an existingunderground sprinkler system to drip irrigation? There are several reasons:

Better water distribution. Most oldersprinkler systems were installed when plants were young. As plants matured, branches may have grown into the spray pattern, disrupting application; some roots may stay dry while others get soaked. By running one or more drip emitters to individual plants, you make sure everything gets watered more evenly.

On the other hand, you may want to waterunevenly. You can buy drip emitters with different application rates, then mix them to meet the needs of specific plants. For example, a small shrub may call for an emitter that applies only 1 gallon per hour; a deep-rooted tree may need twice as much. On a drip system, both would receive the right amount with one turn of a faucet or one flick of a switch.

Slower, more precise application. Inmany cases, a drip system can eliminate wasteful runoff, particularly on hillside plantings. And because water is applied directly to the root zone, less soil is wetted, resulting in less weed growth.

Drip emitters can also eliminate problemscaused when sprinklers are spraying the sides of buildings--or wetting stairs, driveways, or sidewalks, making them dangerously slippery.

Drip saves water. Last winter's low rainfallin many parts of the West and the rising cost of domestic water could be reasons enough for switching to drip.

Drip adapts to garden remodels. Changingto drip can also be advantageous if you're remodeling part or all of your landscape. You can leave part of your existing underground system intact while you direct flexible drip piping to new plantings.

The conversion makes use of existing pipes--little digging is necessary

First you need to position the filter andpressure reducer, then retrofit one riser and cap the rest. After that, it's exactly like installing a drip system from scratch. (For a free reprint of the Sunset article "Drip . . . its time has come,' send a stamped, self-addressed envelope to Drip Irrigation, Sunset Magazine, 80 Willow Rd., Menlo Park, Calif. 94025.)

Remember, you must convert completelyfrom one system to the other. Drip emitters and regular sprinklers will not operate properly on the same line. (This shouldn't be a problem--unless you have a system that waters both landscape plants and lawn from the same valve.)

Where the plant arrangement calls for acomplete wetting--such as a solid planting of spreading ground cover like ajuga or gazania--you can use a microsprinkler connected directly to the drip line.

All the pieces you'll need are available inmany hardware stores, or look in the yellow pages under Irrigation Supplies.

Where do you put the filter and pressure reducer?

To convert to drip, you need to filter thewater to prevent clogs, and you must reduce the in-line pressure to 20 to 30 psi to prevent blowouts. The filter always precedes the reducer in the direction of flow.

You can install the filter and pressurereducer at any one of the risers that hold a sprinkler, or at the valve (in either case, you must have an anti-siphon device at the valve).

Installing at a riser is easier: simply removeall the sprinkler heads, install a filter and pressure reducer at one riser as pictured on the facing page, and cap the other risers. It doesn't make much difference which sprinkler you retrofit, so long as it won't trip people.

This filter--pressure reducer section mustremain partly aboveground so that you can occasionally clean the filter.

Installing at the valve is more difficult,but it eliminates the need for more than one filter and pressure reducer if your sprinklers on one line are separated by a driveway or sidewalk.

The fittings and adapters you'll need(lower left photograph) will vary according to the system you have. Take a drawing of your valve setup (full size or with measurements accurately noted) to the store and do a trial assembly of as many of the pieces as possible as you shop.

You'll have to remove a section of pipebelow the anti-siphon valve; this is much easier to do with PVC pipe than with metal. Dig down several inches beyond where the line makes a 90| turn toward the sprinklers and unscrew the vertical pipe from the elbow there, or cut the pipe.

Install filter and pressure reducer. Thenremove all the sprinkler heads, adapt any one riser for polyethylene tubing as in the photographs here, and cap the rest.

In either conversion, you can bury most ofthe main drip lines. If the capped sprinkler risers would be a hazard or an annoyance, replace them with shorter ones, and cap those.

Photo: The old sprinklers seemed well aimed, butthe water was going on too fast, and too much was ending up in the driveway. The answer: conversion to a drip system

Photo: Adding filter and pressure regulator at a riser

Unscrew sprinkler heads from risers.This type comes off easiest with special tool shown--or use a small pipe wrench

Attach a threaded elbow to one riser, then screw on filter, pressure reducer, and compression fitting as pictured above. Filter must be above the ground for regular cleaning. Insert black poly main line and attach drip emitters where needed (below)

Photo: Adding filter and pressure regulator at the valve

Begin the conversion by installing afilter and pressure reducer at the present valve as above. (This valve is hooked to an electric timer)

To adapt riser for main drip line,glue compression fitting into PVC T or elbow, using plastic pipe cement

Thread adapter onto riser, then pushblack poly tubing into compression fittings with a rocking motion (don't use glue)

Attach each emitter (arrow) whereneeded and bury pipe. Many plants will need more than one emitter
COPYRIGHT 1987 Sunset Publishing Corp.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1987 Gale, Cengage Learning. All rights reserved.

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Date:Aug 1, 1987
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