Drip System Conversion

Another guest how-to post from Tom...

When we first bought the house in 2004, we had a number of large-scale renovations done – central heat and air, new kitchen appliances, a fence around the property (at the time, to keep the kids in), and a sprinkler system. I'd had some experience installing sprinkler systems myself, having created the system for our back yard in the old house, but this was a major renovation for us, so we contracted it out. They installed a pretty typical system – sprays for the lawn areas, mostly sprays covering the fence border areas as well.

As we've worked to convert lawn into growing area, the old spray system became less and less appropriate. It threw a lot of water into the air, and did a pretty good job of spraying the driveway and the sidewalk. We did a little bit of renovation of the spray system to support the beds in the south garden, but a spray system was still very inefficient, watering the mulched areas between the beds as much as the beds themselves. Now that we're converting more lawn to growing area, and entering the "new normal" of California drought, it was time for a change. So, for the past month worth of weekends, I've been working on converting our existing spray system into a drip system. While it's fundamentally a pretty straightforward process, there are definitely some lessons learned.

A basic converted sprinkler head to drip line looks something like this:

Our old sprinkler heads were attached to 1/2" PVC risers, so we had to remove the sprinkler head, possibly add a higher riser, attach a pressure regulator, then a 1/2" PVC to 1/2" poly coupling, and then a length of 1/2" poly hose to act as a water main (secured with a hose clamp). The individual drip system components would then get hooked to this 1/2" poly hose main.

Before actually doing any work, my first step was to walk around the whole house, mapping out where the spray heads come up, thinking about where I'd like the 1/2" poly main lines, and thinking about the kind of drip emitters that would be appropriate to use for the different areas of the garden. Finding all of the existing spray heads was sometimes challenging – I had to turn on the existing sprinklers occasionally to see where they were, and to re-learn exactly which sprinkler system valves controlled which sprinkler heads.

Next, I had to cap off the vast majority of the sprinkler heads. Our old lawn sprinklers were installed around the perimeter of the lawn, about every 6-8 feet, and nearly all of them had to be capped. This meant excavating the old sprinkler head, installing a cap over the end of the PVC riser, and burying it again. I consider myself fortunate that we do not live in an area where the ground freezes, or I would have had to excavate all of the pipe, too. All in all, I probably capped about 40-50 sprinkler heads.

Pop-up sprinkler on left, cap on right
Installing the pressure regulator, PVC to poly coupling, and poly hose wasn't too hard. Based on some advice I got from one of the innumerable YouTube videos I watched about this, I used a little WD-40 on the end of the coupling to help get the poly hose onto it. I had to make sure to apply pressure in both directions (holding the coupling on the riser, opposing the force of the poly hose), so that I didn't snap the pressure regulator.

The ends of the 1/2" poly hose mains are secured with these easy little clamps – you just bend the end of the hose onto it. For drip emitters, I used different things in different areas:

The woodland garden, the pollinator garden, and a few other areas have some sprays installed on some risers.

The raised beds are getting some drip-a-long hose – 1/4" poly hose that has inline drip emitters installed every 12 inches. I also used this in some narrow areas along the fence.

It's important to use tie-downs to keep the hose on the ground
In other fence areas, a couple of strawberry patches, and a few other spots have 360º or 180º little microsprays.

Finally, I've got 1 gph (gallon per hour) emitters installed directly into the 1/2" poly hose running to individual plants, like the blueberry bushes and raspberry canes.

Elizabeth posted recently about learning and mistakes, and there are definitely some lessons learned from this experience. Here are some:

Pressure regulation is important. The pressure regulators are among the most expensive parts of this operation (about $7/pop), but they're vitally important. Without lowering the pressure in the system to about 30psi, you're just asking for those 1/4" hoses to come loose and your drip system to turn into a small fountain system. It's also important for the drip-a-long hose – without pressure regulation, the water comes jetting out of the emitters, instead of dripping out.

The right tool for the job. There are a couple of tools that will make this job easier. One is a PVC pipe cutter. Mine looks something like this:

In addition to working on PVC pipe, it works wonders on the 1/2" poly hose, making quick clean cuts.

The other little tool I got is used to punch emitters and 1/4" hose couplers in the 1/2" poly hose. I initially bought a cheaper punch, but it's nice to have a tool that you can put the emitter in directly, and so it just punches the hole and installs the emitter in one step.

Shopping. I like supporting our local hardware store, but for this project, I found I needed to visit that big orange home improvement store. Their selection of products was vastly superior (our local store just didn't stock things like the pressure regulators), and they had quantities that I needed.

You don't have to be perfect. When setting up the system, you'll be tempted to obsess over getting the various emitters to drip directly on the roots of your plants, but you don't have to be that obsessive – the water will get into the soil and spread out.

All in all, it probably cost us around $400 and four(ish) weekends to get this project done, but it's very satisfying. We've got the drip running in the mornings, and it's great to see water going directly to where it's needed, and not just all over the place. I'm especially looking forward to its use in the raised beds, where the drip-a-long hose gets the water right down into the soil, instead of spraying on top of the leaves and hoping the water gets down where it's needed.