Installing Irrigation System in Mama Dee's Garden

I got back into NYC the other day and met up with Leanna from Mama Dee's Community Garden. She was excitedly looking at YouTube videos about drip irrigation systems. She told me that they needed to replace a leaky hose running from the municipal water on the south east end of the garden leading to another spigot in the middle of the garden.

mama dees garden map

After a quick visit to the garden we sketched out a rough plan and set off to Home Depo were we picked up the supplies to build a system of PVC pipes to run water through out the garden.

supplies in a Home Depo cart

We decided that we would run a pipe along the south wall of the garden and have intersections between every pipe section with a valve, so a valve every 10 feet or so. This way water can be gathered from the back wall at many points in the garden.

Supply list:

  • 150 feet of 3/4" PVC pipe (10' sections)
  • Pair of ratcheting pipe cutters
  • 6' washing machine hose
  • 8 3/4" x 3/4" x 3/4" PVC T connectors
  • A few 3/4" elbow (90 degree) joints (for building around corners)
  • Bag of zip-ties
  • 8 3/4" valves
  • One 3/4" straight coupling
  • One 3/4" end cap with threading

Assembly

After cleaning up a mess in the Peachtree Hills garden a few weeks ago I've learned that freezing water can burst PVC pipes. In the Peachtree Hills garden the PVC system had points where the pipe dipped down. Water collected in those low points and then froze and burst the pipes.

In this design I started the build high and sloped it down. In retrospect I should have used a level to ensure the pipe sloped down.

Building the valve connectors

Between each section of pipe we wanted to place a valve so that any area of the garden wouldn't be far from a water source.

To achieve this we used T intersections with a valve on the end.

T section with valve attachment

This is the completed valve assembly. It is constructed from three pieces.

  1. 3/4" T shaped connector.
  2. A short length of 3/4" PVC
  3. An in line 3/4" valve

Leanna cutting pipe

First we cut small sections of pipe. Leanna used a dollar bill to measure. It's important to leave a bit of space between the connector and the valve so that if we needed to alter the design in the future we could simply cut the short pipe section and add other components. By leaving extra room we can ensure that there is enough extra pipe sticking out of each component to allow it to be attached to something else, rather than have a short section of pipe cemented inside it rendering it useless!

We then cemented the pipe sections to the T joint and valve, taking care to align the valve and T joint in the desired orientation.

Constructing the irrigation system

The next step was to start laying out the pipe. We started at the water source and connected pipe sections together with our T join valve assemblies.

Pipe along wall with a valve

We used extra pieces of PVC pipe to create stands to hold the pipes in place with zip ties.

pipe along back wall

It was a fairly simple process:

  1. Layout pipe section
  2. Cement valve assembly to end
  3. Cement next section

Only when two pipes met behind the tool shed did I deviate from this. Because there is no access behind the shed I used a simple 3/4" pipe coupler.

pipe assembly going around a corner

At one point along the wall we encountered a corner which we had to build an S curve to navigate.

pipe along the wall

I extended the pipe all the way to the far end of the garden. A cap would have been used to end the pipe but we forgot to buy one!

Connecting the pipe to water

The final step was to go back to the beginning and install a threaded connection for the hose. I decided to not extend the pipe system away from the wall but rather attach it to the water spigot using a standard hose. This way we can transition to a rain water system if the opportunity presents itself.

corner connection to threaded end piece

I'm not sure what possessed me to assemble the end section like this, I guess I just thought it looked nice.

connecting the hose to the water system

hose connected to system

With the hose connected we were done. Sadly the city hasn't turned the water on yet so we are unable to test this installation. I'll report back later.