For the best field study of sprinkler timers, click here. Sometimes called weather-bsed irrigation controllers or ET controllers.

For systems where pressure is too low, go the bottom of this page.

Over-pressurized, Spraying Water on the sidewalk and street follows.

This photo shows the sprinkler layout. The spacing is about 10' between each spray head. The parkway is 6 ' wide. Since sprinklers are designed to spray from one sprinkler head to the next, this layout for the parkway will always be less than optimal for water efficiency. When the system is adjust to give head-to-head sprinkler coverage along the length of the parkway, the water will be spraying 10' . So on the corners, most of the water will be spraying on the sidewalk.

shows the non-uniformity of the spray heads.

Fogging is another result of over-pressurized sprinkler system. Fogging is shown in the 2 photos below. Especially in the wind, maybe 1/3 of the water delivered by sprinkler systems evaporates before reaching the ground. Fogging is best seen early morning or late afternoon when the sun angle is low.

shows the non-uniformity of the spray heads.

Excessive pressure in sprinkler system causes fogging


The main step to reduce pressure is to adjust the Flow Control on the top of the valve. Manufacturers of valves ship their valves from the factory with this Flow Control all the way open. This Flow Control is like the faucet on your sink or for your garden hose.You open those valves only enough to give the water and pressure that you need. You seldom open these valves all the way. Your sprinklers should not be open all the way. If I was a manufacturer of valves, I would instruct that all valves shipped be closed and then opened 2 turns instead of left open with 7 or 8 turns. Much water would be saved.

. shows valve and solenoid

Use the controller to turn on the water on the parkway. Then go to your valves and grab and twist each black magnetic solenoid where the low voltage wires attach to the valve. You will feel one of the magnetic solenoids vibrate. That is the valve that is watering your parkway.

Next, take the Flow Control and turn it clockwise to reduce the flow through the valve until you see the sprinkler pattern on the parkway change from fog to raindrops. (It may be hard to close the valve with the water flowing.) As raindrops, the irrigation water will travel farther even in the wind. Continue closing the valve to skrink where the sprinkler pattern so that spray from one head is passing a little beyond the next sprinkler head. If the spray is not reaching the next sprinkler head, then turn it counter-closkwise to increase the flow. You must not reduce pressure so much that the heads to pop-up to their maximum height. So this adjustment sometimes requires compromises to avoid over-shooting of sprinkler water as shown below

After you make this adjustment on one valve, you can screw the flow controller shut on all the other valves and then open the flow control on each valve 2 turns as good starting point.

For systems where pressure is too low.....

Systems with pressure that is too low for head-to-head sprinkler coverage are often the result of selecting the lowest bid. In such bids, too few valves and too thin pipes are used to deliver water to the spray heads. These systems often create "donuts" around each sprinkler head where enough water is only present in circles around sprinkler heads and yellowish grass every place else. An often used practise is to wastefully increase the runtime for each valve to give enough water to the yellowish grass.

When suggestions are given to improve the coverage of the sprinkler heads, it often involved adding valves and irrigation lines. This extra work is often expensive. A better and lower cost solution is to use stream-rotor sprinkler heads as shown below. Note that water is NOT spraying in all directions at all times. Instead the water streams are slowly rotating over a 90 degree arc. This type of rotating sprinkler head delivers water only 1/3 to 1/4 the rate of standard spray head that is covering 90 degrees of arc. So the runtime of the valve must be increased 3 or 4 times. Since only 1/3 or 1/4 of water is flowing out the sprinkler valves and down the underground sprinkler pipes, the pressure is restored so that head-to-head sprinkler coverage is easily achieved.

These sprinkler heads are available from Home Depot and are called MP Rotators. They cost about $5 each. Only the top part of the sprinkler head is replaced. You do not need to dig below ground. They have female threads, different arcs which are adjustable and have different ranges. You need to check that your sprinkler heads have male threads. You need to measure the head-to-head sprinkler distance. I made this change to my Mother's sprinkler system in a couple hours with excellent results. It cost her $70 instead of $500 to add a valve and dig her lawn to lay new pipes and sprinkler fittings.The MP Rotators can be found at the following web link.

Toro makes a similar sprinkler head which they call PRN (Precision Rotating Nozzle) which are available with either female or male threads. These sprinkler heads and where to buy them can be found on the web link below.

shows rotating stream rotors