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		Watering

Install an Underground Sprinkler System
Level of difficulty: Advanced

Getting tired of dragging the hose all over the lawn? Put in an underground sprinkler system and you can water the lawn and garden with the turn of a knob. Sprinkler systems also provide an even watering which gives the grass an even green color. (Say good-bye to the brown patches!)

There are different types of pop-up sprinkler heads that can be used in your sprinkler system. There are heads used for for trees, shrubs, lawn, etc. that vary in the type of spray pattern they produce, from a fine spray to a solid stream However, use only one type of head in your sprinkler system. (i.e., if you want to water your lawn, you have to use all lawn heads.) Most heads are adjustable with a 45 to 360-degree coverage from the same head. And they are designed to use a lower rate of water.

Before you begin there are a couple of things that need consideration.


	Caution: Check the Codes

		Look into the local building and water codes. They tell you if there are any restrictions on an underground sprinkler system. You also need to know where any underground pipes or water mains are located. Your local Department of Public Works can tell you this information.

Finding Flow Rate

Before you install a sprinkler system you need to know the flow rate, gallons per minute (gpm), of water for your home. Using the outside faucet, turned fully on, time how many seconds it takes to fill a one gallon container. Divide 60 by the number of seconds. This is your home flow rate. (An example is if it takes 5 seconds to fill a gallon, your home flow rate is 12 gpm.)

Layout of Sprinkler System

		Before you buy anything it is important to make a layout of your house. Plan your sprinkler system and draw it out on graph paper. Plan for proper overlap of the spray to avoid dry spots in your lawn. Find out from the hardware store the diameter of the area the sprinkler head covers and it’s flow rate (gpm). Larger heads have larger diameters of coverage which means they require a higher flow rate. The sprinkler system can use 60 to 75 percent of your home flow rate. The sprinkler system rate is found by adding up the required flow rate (gpm) for each sprinkler head. If your sprinkler system total is higher than 75 percent of your home gpm, you have to use fewer heads or use smaller heads which have a lower flow rate requirement. Bring this layout with you when you go to buy parts. Your local hardware store can help you figure out how much pipe you’ll need and how many connectors, elbows and T-fittings you’ll need.

Pipe

The best type of pipe to use for the sprinkler system is PVC or CPVC. (In this project, the only difference between the two pipes is the diameter. In regular plumbing the PVC pipe is used for drain and waste while CPVC, chlorinated PVC, is for hot and cold water lines.) They are light and easy to work with, plus they won’t corrode. The diameter of your pipe is determined by your sprinkler system flow rate. Use 3/4-inch pipe for 14 gpm, 1-inch for 25 gpm, or 1 1/4-inch for 40 gpm. If you have a different gpm, ask you local hardware store for the diameter of pipe you need. The diameter of pipe is also used as the diameter of the valves and fittings.

Tools and Materials you need:

Graph paper Wrench Iron or steel T-fitting, threaded (may need reducing T-fitting if diameter of pipe sticking out through wall is different than the diameter needed for the sprinkler system) Iron or steel close nipple Iron or steel hose bibb, threaded on inside (if diameter of sprinkler equals the diameter of pipe that sticks out of the wall, you can use your old garden faucet) Teflon plumbers’ tape to go around the threads of the adapters PVC or CPVC male adapters (5 to get from the outside pipe to the start of the underground pipe-run, 1 for each sprinkler head and 2 for each automatic drain valve) PVC or CPVC pipe Hacksaw or tubing cutter Utility knife Felt tip pen Emery cloth Solvent glue and primer Anti-siphoning valve Gate valve Shovel Gravel PVC or CPVC fittings (these are rings of PVC or CPVC that you use to connect two pipes) PVC or CPVC elbows (when you want to make 90-degree turns and if you want a sprinkler head at the end of the pipe-run) PVC or CPVC T-fittings (when you want a branch to come off the pipe-run and for each sprinkler head that isn’t at the end of the run) Risers, a piece of PVC or CPVC that goes up from the pipe-run to the sprinkler head (one for each head) Sprinkler heads Stake, wooden block and wire to support heads (one for each head) Automatic drain valves (one for the end of the run and the ends of any branches) Plastic solvent cement Plastic electrical tape


	Tip: Ground-Breaking Advice

		Water the ground a few days before you dig. This softens the ground and makes the whole job easier. Cutting the Pipes Use a hacksaw, it's easy to use and you probably already own one. The only problem with a hacksaw is that you have to support the pipe in a portable gripping bench or a vise. Also, you have to make sure you cut straight. A tubing cutter is probably something you don’t already own, but it is a good investment, especially if you are going to do more plumbing projects. The tubing cutter works by placing the pipe in the vise of the cutter, tightening it until it is snug. The cutting wheel needs to be on the line where you want to cut. Rotate the cutter once, then rotate it in the other direction, tightening the vise after every 2 rotations, until it is cut. Whichever method you use, after the pipe is cut, always take off the burrs with the utility knife.

Step 1. Check for Proper Valves and Drains

		Inside the house, look for where the water pipe leads from the meter to the outside faucet. On this line there should be a stop valve. If there isn’t one, you need to install one. This stop valve separates the sprinkler system from the house water. Also, in winter you can turn this off so that you can drain the system. There should also be a drain attached. If there isn’t a drain, install one.

Step 2. Attach T-Fitting and New Faucet

Above ground diagram

Turn the water off at the stop valve that is on the line to the outside (you may have just installed one). From now on the work is outside the house. Detach the outside faucet by unscrewing it with the wrench. Screw on the iron T-fitting so that you have one projection coming straight out and another projection going straight down. Put the iron close nipple into the straight out projection and then attach the new, or old, faucet.

Below ground diagram


	Tip: Pipe to Pipe Connections

		To attach any plastic to plastic (fittings, adapters, T-fittings or elbows) you use plastic solvent glue. Before you apply the solvent, you need to prepare the plastic. First, test fit the pipe and the other piece. Mark the pipe and the other piece with the felt tip pen so that you have alignment lines. Also mark along the edge so you know the depth of the socket that the pipe fits into. Use the emery cloth and clean the end of the pipe and the inside socket on the other piece. Prime the end of the pipe until the horizontal line, and the socket with the plastic primer. Apply a thick coat of solvent to the outside of the pipe and a thin coat to the inside of the socket. (Work quickly, the solvent dries in 30 seconds!) Position the pipe so that the alignment lines are about 2 inches apart. Shove the pipe in until it hits the back of the socket, then turn the pipe until the marks align. Hold for about 20 seconds, then wipe off any excess glue with a rag. The turning causes a solid bead of solvent to form around the pipe. Wait about 2 minutes before you handle it again.

Step 3. Attach Anti-Siphoning Valve

Now you start working with PVC or CPVC pipes. Cut two small pieces of pipe. (Length depends on how high up the outside pipe is.) Attach male adapter to one end of each pipe. Put Teflon plumbers’ tape on the threads of the adapters. Screw one of the pipes into the down projection on the T-fitting. Attach the other short piece of pipe to the pipe, now screwed into the T-fitting, with an elbow. The elbow can point to the right or left. (See Both Figure's Above Step 2.) Attach the anti-siphoning valve onto the other male adapter.

Step 4. Install Gate Valve

Cut another small piece of pipe and attach male adapters on both ends. Put Teflon plumbers’ tape on the threads of the adapters. One end of the pipe goes into the anti-siphoning valve. The gate valve attaches to the other end of the pipe. (See Top Figure of Step 2.)

Step 5. Shovel Out Trenches

		Cut your trenches, starting where the pipe comes down the side of the wall. The starting point of the trench needs to be 9-inches deep. As you dig your pipe-run the trench needs to get 1/4 inch deeper after every 5 feet. This slope allows the pipes to drain. The trench should be as wide as your shovel. Put plastic runners on both sides of the trench to avoid damage to your lawn, one runner for the sod and the other runner for the dirt. Continue with the slope wherever you branch. Line the trench with 1 inch of gravel. This helps the water drain. Drive a stake to mark where the heads go.

Step 6. Link Gate Valve to Pipe-run

Measure the length of pipe needed to reach from the end of the gate valve to the bottom of the trench. Take into account that there is a male adapter at one end and an elbow at the other. Attach the adapter (with Teflon plumbers’ tape on the threads) and elbow. Dig out the gravel that is right under where the pipe goes so that you can attach the pipe to the gate valve. Attach it, then scrape the gravel back around the pipe elbow. This elbow connects to the beginning of your pipe-run.

Step 7. Install Pipe-run

Measure, cut and connect the pipe to make your pipe-runs, laying it in the trenches as you go. Use an elbow to turn corners and a T-fitting to make branches. Wherever there is a head in the run, there needs to be a T-fitting. One of the projections of the T-fitting needs to be up. (See Both Figure's Above Step 2.) Place the automatic drain valves into position at the end of the run and branches. Use male adapters to attach them with Teflon plumbers’ tape on the threads. The automatic drain valves empty the water whenever the system is turned off.

Step 8. Attach Sprinkler Heads

		Cut the risers so that the heads of the sprinklers are flush with the ground. Take into account the socket depth of the T-fitting and the male adapter that you have to add to the riser. Solvent-glue the adapters to one end of the risers. Add Teflon plumbers’ tape to the threads. When this is dry you want to attach the risers to the T-fitting. To support the riser, imbed a stake next to the head. Attach it to the riser using the block and wire. Put on the heads.

Step 9. Test Sprinkler System

Wait 24 hours for all the solvent to dry and then test the system. It may take a minute to flush out the joints. If there are any leaks, fill the hole or crack with plastic solvent cement and wrap it with plastic electrical tape. When the entire system works, fill in the trenches with the dirt and sod.


	Tip: In the Winter

		Turn the water stop valve, inside the house, off. Open the inside drain and place a bucket under it. Outside, turn the hose faucet and the gate valve for the sprinkler system on. This should get rid of water that is left in the pipes. The automatic drain valves open to let out the water whenever the sprinkler system is turned off.