What I Learned Installing My Sprinkler System

The following section explains how to avoid the problems in these areas

Connection to water main

This is the single largest risk to your system because it is always under pressure and once you cut your line and install a new connection (which usually involves glue), you'll probably bury it under dirt. You may never know if there is a leak or if a problem occurs unless your water bill is huge or your service suddenly stops. In addition, any solution you install will probably involve a compression coupling, which is inherently a weakness in the system.

The way to avoid problems in this area is to plan well and pre-assemble the fittings.

First, plan exactly what pieces you will install and how much you will need to cut out of the water main. To do this, you will need to dig down to your water main and get the diameter (use a piece of string - know that PVC walls are 1/8th inch thick). Gluing the solution in place is more reliable than using a compression, but you will probably need to use a compression coupling in order to get everything together.

I found it best to tie into the PVC section (my line was 2 ¼ inches diameter) instead of the galvanized steel 1 inch section. This is because PVC is much easier to work with than steel.

Pre-assemble everything. Let it cure at least overnight. Assemble it in a clean place like your living room.

To install the new connection plan to keep the main water turned off for 2 hours. After turning it off, cut the part of out of the water main that you need. Put in your pre-assembled part and glue it/install the couplings. If you install couplings, make sure the pipe is super clean and that you crank it down all the way so threads don't show. Let the glue cure for at least 1 hour before letting water touch the new connections.

Install more pipe than you need and put a male adapter on the end so that you can install a cap. You'll cut this off later. But it will let you cap the pipe so you can test it.

After everything is cured for 1 hour, turn on the water pressure fully. Look to see if there are any leaks. Dry off all pipes and then look for any escaping drips. If there are any drips, make sure to address these immediately by installing new connections or cranking down the compression coupling. Do not proceed unless all drips are solved.

Connection to backflow preventer and master valve

This is where you get to do an extra quality job. Do not skimp on any parts of the master valve or backflow preventer because you never want to deal with these items again.

The first thing you have to do is plan this out carefully. Let's assume you're going to install a master value and a double backflow preventer. Make sure to get a good brass master ball valve and a good brass backflow preventer. Try to get everything in the 1 inch kind.

You're going to pre-assemble everything from the water main connection (to that pipe you left the end cap on) to the PVC pipe after the backflow preventer in your living room (the day before you plan to cut the water main). You'll need a few special items: 2 pipe wrenches and lots of Teflon tape.

You need to install these items in an L shape so that the brass items will sit above a bed of gravel. This is important if you ever have to do maintenance. The top of the backflow preventer can be just below the soil level and the enclosure will still cover it.

You'll want to pre-assemble this section. Cut the PVC to the lengths you want and put the threaded couplings on the end of the first one. Let it cure at least one hour. Put 3-6 layers of Teflon tape around the threads (make sure they're clean). Don't use pipe dope. Using the 2 pipe wrenches, crank the PVC couplings into the brass connections as far as you can (2-3 turns after what your hands can do). You should have no more than ¼ inch of threads showing. Using the next section of PVC, glue on the male adapter and let it cure. Wrap it in Teflon tape and crank it in too. Put this section down for a moment. Take a male adapter and wrap it with Teflon like before and crank it to the upstream part of the backflow preventer. After its in as far as you ccan get it, glue it to the PVC pipe from the master valve. By cranking it in place first, you are assured that the orientation of the valve and backflow preventer will be correct. Now glue the last threaded coupling to a longer PVC section and Teflon it and crank it in place. Later you can cut that PVC pipe to length if needed.

When you're ready to install this pre-assembled section, just turn off the master water line, cut off the male adapter you left for the test, and install a coupling to your new section. Make sure there isn't any stress on the line by placing temporary rocks under the line to support it.

The enclosures you select should not touch any PVC, only gravel.

To test this new section, install a male adapter like you did before and put an end cap on it. After letting the glue cure of 1 hour, pressurize the entire section. You should get no leaks. If you do get leaks, stop and tighten the threads so they stop.

Now replace your temporary holding rocks with gravel. Since you made an L shape, the master valve and backflow preventer should sit nicely above the gravel. Place your enclosures on top of the gravel and make sure they are level with the soil around them. You may have to lift them out and add more gravel. Once you are satisfied with the lid level of the enclosures, fill around them with dirt. Pack it down real well by walking on it.

Connection to valves

At least 2 connections on every manifold are under constant pressure. These connections need extra care - just like the connections to the backflow preventer. Use the same as the backflow preventer to avoid problems.

It's best to buy the pre-assembled manifolds since they have less joints. Make sure to get the correct adapter thread sizes and watch the genders. Also, some pre-assembled manifolds come with unions (that have washer seals). These are very good.

You can pre-assemble PVC to the threaded connectors. This is good since it is easy to glue a coupling in place once you get in the dirt. Once again, crank these down as far as you can. By don't over-crank as you may crack the PVC (you may not be able to see the cracks either).

Make sure there is no stress on the manifolds or else leaks may develop. To avoid stress, consider installing a few inches of rubber PVC pipe a few feet upstream and downstream. You'll also want to make sure you have the L shape again so that the valves are above the gravel.

The non-pressurized connections in the manifold require less attention and can leak without big impact.

Control wire connections to manifold leads

The issue with control wire is that it must be waterproof. Use nothing but grease caps. Check out a tutorial divoted to this subject (scroll down to "Wire and Splices" for more information about water capillary action and what it can do to your solenoids). You will flood your manifolds at least once, so don't try to cut corners with this.

Connection of manifold to zones

The connection between the valves and the zones is not under constant pressure. But you want to minimize leaks. The issue here is that the connections can't be under any stress - especially if you have pre-built manifolds with rubber gaskets in connecting unions. This means that the pipe must come off the manifold perfectly parallel. Use lots of Teflon tape. And once again the rubber PVC pipe might provide one degree of movement to relieve any stress that might be on the joint. You'll also want to use the L shapes again so that the valves sit above the gravel. The top of the solenoids can be just below ground level and the enclosure will still cover them just fine. As much as possible, pre-assemble the manifolds in a dry place and get a friction wrench to crank down the unions. Use a pipe wrench on the normal mail-female joints. Remember that glued sections rarely leak and problems tend to be around the threaded areas.

Three valves fit in a standard 12x15 enclosure just great. Don't cram any more in there than that.

Glued joints

PVC glue is like magic. It isn't really glue - it is a weld. So this means that a glued joint is actually stronger than normal PVC pipe. For this reason, joints that are well glued are not likely to leak.

To glue the PVC pipe to a coupling has three simple steps:

Clean the PVC pipe (use a primer - really just acetone)
Goop up the pipe and the connector. Be generous.
Insert the pipe into the connector and twist it until it sets.

You can buy special PVC glue that works in the rain. There are also different weights. The guy at Home Depot told me that the different weights are for different types of PVC. Typical schedule 40 doesn't need anything special.

Control wiring

The issue with wiring is that it carries an electrical current (24V, 1-2A). This means that it should be waterproof. You'll want to buy the wire that is designed for sprinkler systems. This stuff has 7 strands, each separately shielded. The outer wrapping is waterproof.

You only want to have connections at the solenoids and the control box. So make sure to buy wire long enough.

I ran my control wire through ½" PVC. Most sprinkler systems just put the wire into the trench and cover it with dirt. The advantage of putting it in PVC is that I was able to route not only control wire (7 strands), but I was able to easily route an 8th strand for my spare solenoid. The other advantages are that I won't be likely to cut the wire with a shovel, it will last longer because it is kept clean, rodents won't knawel on it, and I was able to more cleanly route it into my garage and to the control box. But there are two disadvantages (one that you can work around if you plan correctly). The first disadvantage is that laying the extra ½" PVC pipe took me about 8 hours ( I routed about 150' of wire). The second issue is that the pipe where the wire runs filled with water once when my manifold flooded. So water flowed up into the tube and it took a long time to dry out. I should have found a clever way to plug the PVC pipe at the terminal.

If I were to do the system over again, I wouldn't route the control lines through PVC.

Flushing the system

This is messy, but has a big impact on the finished product. If you don't flush your system before you attach the heads, you will have major problems. But if you take just a little bit of time to flush, it will pay huge dividends (this is why it is low risk but large impact).

I flushed according to Jess Stryder's tutorial. First I flushed each zone for 5 minutes with all sprinkler risers removed (if you have a head and unscrew the top, you can remove the riser). Then I detached all the sprinkler head casings (so all that was left was the swing joint) and capped all but one. Then I flushed each individual joint 2 minutes. It worked great to have Monica, my wife, work the control box while I watched each head and prepped the next one. By this time we had all the wiring done and the zones pretty well known, so we used the timer to run each flush for the exact amount of time.

After I was done flushing I put the heads on (the casing and the risers).

Utility lines

A week before I dug I called 800-245-4545 ("Call Before you Dig"). They gave me a confirmation number and it is hugely important that you keep this number safe. They marked everything for me but the tolerance on the markings was very big (19" on both sides). So it was of little help. However, if you are home when they come, they will tell you how deep the line is (they aren't supposed to, but they usually will). This information is very helpful because it tells you whether the particular line is an issue or not. For example, the cable company told me that the coax was about 3 inches under the grass. This was very helpful in me finding it.

I did cut my telephone line (while digging for it by hand). But since I had the confirmation number that said that I called before I dug, the repair was free.

Impact to yard

There are two impacts that you should warn your wife about: you may hurt the trees and shrubs, and the grass will be messed up for a few months (or 6 months in my case). Make sure to get signoff on both of these or face the consequences.

The issue with trees here in Texas is that there is no big, deep taproot. So trees live by sending out roots in all directions. Most likely some of your trenches will go near a tree. So try to stay out of the drip zone. In my yard, went ahead and trenched when I was about 5-10 feet away from the trees, but tried to always trench in parallel with the roots, never across. When I dug by hand, I never cut a root that was a larger diameter than my thumb. When I encountered larger roots (and there were a few), I dug under them and PVC'd around them.

I also had to dig up parts of my garden. I'm sure my bushes didn't like that too much.

The second impact to your yard will be your grass. I didn't attempt to save my sod. It would have added 2-3 more days onto the otherwise too long project. Plus I figure watered grass will grow faster anyway. When I put the dirt back over the trenches after all was done, my yard didn't look half bad. It just looked like someone dumped a lot of dirt onto it.

Grass is impacted when you leave soil on top of it for a long time. My grass was buried for about 5 days and it didn't hurt it at all. But a friend took more than 4 weeks to get the dirt back into the trenches and he had dead grass where the soil had been. I have St. Augustine, so it is hard to kill.

This project is muddy. Make sure to warn your wife.

Homogeneous precipitation rates

Precipitation is the amount of water that falls on a particular point in your yard. The goal of a sprinkler system is that the precipitation rate over your driveway is zero while the precipitation rate over your grass is constant. This keeps your yard from getting dry and wet places. If you try to design a system yourself, you better get the right tools to help solve this complex problem. If you use a service like Rainbird, like I did, they take care of it for you.

Head-to-head coverage is what allows for homogeneous precipitation rates. This means that each sprinkler head will spray all the way to its closest neighbors.

Adjustment of spray patterns

I was clever (thanks to Chad Chesney). I bought all adjustable heads. You can buy the right shapes and sizes, but in the end, few yards have nice perpendicular geometries. Adjustable heads also have the advantage that they keep you from having to keep track of specific head shapes. Now all my heads are replaceable by the same item and I was able to precisely adjust each one. But adjustable heads are more expensive. But the additional cost is a small issue compared to the total cost.

Enclosure locale

The enclosure is the box that encloses the manifolds and is mostly below ground. The issue with placement is mostly that it needs to be conveniently accessible to the main line and the zones. You should also clear the placement with your wife since it is one of the few things that are visible after the system is installed and the grass grows.

Swing joints

These are very cool. They serve two purposes. First, they provide the necessary stress relief so that if you step on a head or run it over with the lawnmower, it puts no stress on the PVC pipe (and thus won't crack or break). Second, it makes head installation easy and accurate.

These devices will run you about $2.00 - $2.50 each. But they are worth it. You can buy them from the local irrigation supply store (not Home Depot or Lowes). Since my heads were ½", I bought the correct sized swing assemblies. My rotor heads were ¾" so I just bought bushings to convert from the ½" swing to the sprinkler head.

I put Teflon tape around each joint to prevent leaks, but I think this was overkill. To do 55 assemblies, it took me nearly 8 hours and I did this in the evenings the week before I did the installation. These devices are only under pressure while the zone is on, so leaking is not a problem. I would not install the Teflon tape if I did this again.

I pre-assembled all my swing assemblies with the sprinkler casing and the appropriate PVC connector and tightened it by hand. So I had a lot pre-assembled and this made it much easier to connect the heads to the PVC pipe.

I had laid out all my connections on my grass the week before so I knew what kind of PVC connectors I would need. I then put each completed assembly into a ziplock bag with a number that corresponded to the map of my yard. So I just dropped all the bags in the right places after the trenches were dug and then just cut the PVC pipe to length and pulled the connections from the plastic bags. This was easy, well organized, and kept all my parts clean. Since I had laid everything out carefully, I already had purchased the PVC pieces I forgot during my first trip (so this helped me be more efficient). As a result, I needed to stop progress only a few times to make a trip to the store.

Covering trenches

I didn't try to save my sod as I dug the trenches (I didn't have time for that). So when I got done I had little piles of dirt that ran beside the trenches from the Ditch Witch. It took me a few days to get the pipe in the trenches and then to cover it back over.

By the time I got to covering the trenches, it had already rained twice. The little piles of dirt were like concrete and it was very painful to cover the trenches. Plus some of the dirt was lost, so I was not able to cover the trenches fully. You will need more dirt than you removed because some of the dirt gets worked into the grass and is not recoverable.

The best advice I can give is this: get your trenches covered as quickly as possible. The ideal situation is to lay the pipe right behind the trencher - and cover it back up immediately. If you don't, be prepared to work harder, damage your grass, or buy a bunch of fill dirt.

Head connections to PVC

Since I used swing joints, I never connected the sprinkler heads directly to the PVC pipe. I used Teflon tape to connect all heads to the swing joints for two reasons. The most important reason is that Teflon tape provides lubrication which prevents the threads from locking. This means that you can actually remove the heads even after you tighten them down. Heads will need to be replaced at some point, so the tape makes it much easier. The second advantage is that the Teflon tape helped me tighten the heads down pretty far; I got better seals and less leaking around the heads.

Timer Control box (placement and connections)

The control box is pretty simple to get right. The issue is really convenience and protection from the elements. Even though I placed my controller in my garage, I still put a waterproof enclosure around it (the enclosure actually came with the controller). My garage is a dusty place and I wanted to protect the brain of the sprinkler system. I also routed all the control wire through ½" electrical conduit which I then mounted to the wall. This gave it a cleaner look and will help me not snag with the lawn mower or my tools.