Start with the head assembly, which can consist of many different components. Every part must be completely debris free, and the best way to make certain of this is to disassemble the head, clean each piece with water, and put it back together. Check the seals as you reassemble; making sure it has been tightened securely to prevent any leaks.
The backflow is an important part of the head assembly. Since a broken backflow, or an unseated diaphragm within the backflow, can contaminate your drinking water, it is vital that you make sure no air is able to enter form the water outlet side. Air blown in from the outlet side should not be able to pass through the backflow. If it fails the test, give it a slight shake and try again. Also, look for debris that might be causing issues. Air should blow right through when directed from the inlet side of the backflow. If the air flow is blocked, look for debris that might be causing issues. If air is not entering freely from the inlet side, or being blocked from entering the outlet side, more than likely you need to replace the device. A faulty backflow device is never a good thing.
Although your filter may not seem as important as your backflow device, it is key in keeping debris from entering your valve or emitters. This is where those old toothbrushes you have lying around come in handy. Take your filter apart and remove the individual pieces. Use a toothbrush to clean the filter screen with clean water. If you choose to use soap, make sure you thoroughly rinse it off, since soap residue is not a good addition to your drip system. Make sure you don't have any debris stuck in the flush cap by removing it form the filter body and rinsing both sections. Check all parts and pieces closely for loose, stuck, or hidden debris. Put all of the pieces back together. If your filter has an O ring located on the top of the filter body, it may have dried out over time. A dab of Vaseline around the O Ring can help these pieces glide back together. Carefully slip the screen back into the screen slot, positioning the correct O rings on each side, and screw the two main body parts together. Replace any old Teflon tape with new tape before reinstalling the filter into the head assembly.
Probably one of the easiest steps to complete, the valve simply needs to be washed inside and out. Check that only Teflon tape is used on any threads leading into the valve, but make sure all loose tape is removed as this can get into your valve and hinder its operation.
Checking your DC or battery operated valve is much more involved. Do not make a move without first insuring that the solenoid On/Off lever is in the upright position. Water flow into the valve must be turned off, and any remaining water pressure needs to be released. Now it is time to remove the solenoid by carefully make a quarter turn to the left, and then lift if from the bayonet. Keep up with the O ring located between these two parts. It may come off with the solenoid, or remain with the bayonet. Check the O ring for cleanliness, then remove the small round yellow piece located just inside the bayonet. Use of tweezers or another type of long-nosed tool will be helpful. Do not loose this piece. You will now need to gently turn the water on, allowing a small round stream of water to emit from the area where the round yellow piece was located. If more of a water spray is noticed, blockage is occurring. Allow the water to continue for a few minutes, since even this slight water movement is often enough to clear the blockage. If further assistance is needed, turn off the water and attempt to remove any debris with a pin. Run the test again and hopefully the blockage has been eliminated. If so, you can now reassemble and continue on to the next step.
However, if the blockage is still evident, you will need to go further in your attempt to clear the valve. The next move is to unscrew the bayonet from the valve. This must be done very carefully since the bayonet may have become brittle over time. Skip the tools and attempt to only use hand pressure. Look closely: a small O ring will be located between the bayonet and the valve. Although very easy to misplace, this ring is vital to the valve's operation. Look through both openings of the bayonet and see if you can see any debris. Once again, forgo the tools and use your own air, not a powered air supply, to try and clear any blockage inside. Turn the water on again, just slightly, in an attempt to remove any debris that might be located inside the valve. Reattach the bayonet to the valve without using Teflon tape of glue. The O rings provide the seals. Test the valve again. Reassemble the remainder of the valve, making sure that the small round yellow piece faces downward toward the valve. If the O ring is installed onto the bottom of the solenoid, it will be easier to keep in place when attaching the solenoid to the bayonet. Make sure the On-Off lever is facing away form the valve, since this makes it easier to turn.
Unfortunately there isn't a procedure to test pressure regulators unless they are already installed and even then it is only possible to notice if other parts of the system are showing evidence that the pressure is too high. Remember, water flow rate is not dependent on the pressure regulator. The best you can do is to simply make sure it is clean of debris by rinsing the unit out. Make sure the Teflon is completely stuck to the unit and any loose tape is removed.
If your system is equipped with swivel adapter, check to see if the threads aren't stripped, there is no evidence of cracks, and all washer connections are still viable.
After giving your complete system a run through, the next step is to flush out the lines in your irrigation system. This will eliminate any dirt that may have crept in during the off-season. Open up the lines that are inch or larger and remove the valve section from any flush valves you had installed. Keep this valve section in a clean area while you allow water to run down the lines for a few moments. Check your largest, or main, line first. If water is running clear, close it off and proceed to the next line, always working from lines with the most water flow down to those with the least. Continue this procedure until you have closed up all the lines in your system.
Now it is time to take a visual inventory of your drippers and micro-sprinklers. Make sure that all drippers are emitting some water flow; the rate will depend upon the flow rate of your system. If a clog is suspected, block the water flow for a moment at the dripper outlet - release - and repeat. If the flow still appears to be obstructed, you may need to plan on replacing that dripper. A few dripper styles can be removed, taken apart and cleaned, or blown out.
Micro-sprinklers should not be installed until after an initial flushing has been completed, since removal can damage the threads. Once installed, however, there are a few measures you can take. Move the adjustment, if possible, from off to full in an attempt to correct the flow rate. If unsuccessful, disassemble and clean an adjustable sprinkler whose design makes this feasible. When all else fails, replace the damaged micro-sprinkler. Fixed-flow micro-sprinklers offer another set of problems. Two easy checks are to see if any deflectors are loose or missing and to wipe off the water outlet in case any blockage is external. The next step is to turn off the water flow, blow back through the sprinkler, and switch the water back on. Dirt inside the line is suspected if the sprinkler is operational for only a few moments. In that case, remove the sprinkler from the line, blow through it from the outlet side, turn the water on for a short time, and then replace the sprinkler. Your last option is to replace that sprinkler.
Your final tests will be on your complete irrigation system once the components have checked, cleaned, and flushed. When everything appears to be running smoothly, you need to walk every line and look for leaks. Since water has been flowing through the system for some time now, it will be easier to notice wet spots which will indicate a leak in a buried tube. This is important, since it is fairly easy to spot leaks located above ground. Goof plugs can be used to seal many holes, but always try to inset the small side first. If a plug doesn't work, cut the line and install a coupling to reconnect the tubes. Leaks that appear at fittings may be the result of a tube not being pushed in far enough to create a good seal. When the leak stems from a barb connection, try additional pressure on the barb or giving it a good turn. A final solution requires removing the barb, plugging that hole, and re-installing the barb in a new hole.
Now take a look at how your irrigation system is performing as a whole. This visual check requires you to notice if all sprinklers and emitters are receiving adequate water flow. Also, notice if adjustments need to be made, based on dry areas or evidence of puddles forming. Perhaps the most noticeable problem would be a sprayer sending water ineffectively into the air, definitely in need of adjustment. Checking the battery on your AC or battery operated controller may seem like a given, but you might be surprised at how often this simple item is overlooked. While AC models use batteries solely for a backup power supply, they are the main power source for the battery operated controller. It is even possible to overlook a "low battery" indicator. You should also make a visual check of the batteries themselves, since they can corrode or leak over time. If there is evidence of moisture inside the battery compartment, wipe it dry and apply a dab of Vaseline to the cover's O ring before closing the box back up. While you are at the controller, make a visual assessment of it as well. Check the date and time displayed on the screen and make any necessary changes. Monitor your water cycle programming, checking for appropriate start and end times, as well as water frequency and duration. Then cycle through each setting by turning each on manually and check that the valve and all connections to it are activated. Make any necessary adjustments to the flow control and confirm that the manual On/Off lever on the solenoid is straight up in the auto position. Finally, check all wires running from the solenoid to the controller. Bare spots are a problem waiting to happen and need to be fixed immediately.
Although this check-up may seem time consuming and unnecessary, preventing major problems before they happen will save you both time and money in the long run.