The spring season has many of us looking to use automatic lawn sprinklers to do our watering. Hopefully you have read my post on Chasing Lawn Sprinkler Leaks. This is a good start, but it just barely touches the subject of efficiency. Besides fixing leaks, there are numerous items that can be performed to make your system more efficient without sacrificing performance. Today, the dollar cost of water is still very reasonable, however water conservantion is really about using less and the long-term benefit. Even though this article will address issues specifically related to systems designed with pop-up type heads, many of the suggestions will work with other types as well.
General Design Considerations: Understanding how an irrigation system is engineered will help you understand how to make one work more efficiently. If you have a “blueprint” of your system you have a head start, if not, we will perform some hands-on analysis to obtain performance information.
- Elements of Design: All systems are designed based on water usage and gallons of water (GPM) per minutes used by each head. Typically the small pop-up heads use more water per head per square foot watered. Because they apply more water per square foot than other types, they work well for small and medium-sized residential properties. They can also be easily tuned to fit odd spaces with a host of nozzle choices.
- Zones or Sections: All sprinkler systems are broken down into zones or sections. The Irrigator calculates the zone size by using available water pressure, pipe size and maximum GPM per zone. Besides these items, zone adjustments may also include special watering needs such as side yards, gardens, flower beds or odd-shaped areas. Since additional zones require more material, labor and money many Irrigators will keep the costs down by limiting the number of zones installed, this is good for him and maybe not so good for you. As you analyze your system and you see one head out all by itself in the middle of another zone, the Irrigator needed a head in that location but did not have enough water budget left in the prevailing zone. This is all very common but can be problematic if you are attempting to manage your water usage at a higher degree than normal homeowners.
- Sprinkler Heads & Nozzles: There are a half a dozen types of sprinkler heads, but the pop-up style is still the most popular because they can meet varying needs. Pop-ups can be purchased in different levels of spray coverage and are promoted as providing better coverage because they are typically spaced closer together. Typical systems use heads designed with 10′, 12′ and 15′ radius spray patterns as well as strip sprays and bubblers. Larger properties can use Impulse or Rotary style heads to conserve water as they can be placed very far apart. Because they distribute water in more of a stream vs. spray found with a pop-up style, they do not waste quite as much water per square foot. Impulse and Rotary heads work well with wide open lots, but don’t work well when there are obstructions such as building structures, trees, and property lines.
- Mixing Head Types: No matter the sprinkler head style, it is perfectly normal to find a mix of spray pattern nozzles within each zone, and a mixtures of head types in a system, but NOT a mixture of head type (Pop-up, Rotary, Orbital) in the same zone. Mixing head type can make it difficult to properly manage coverage and watering levels.
- Optimal Design: The best designed systems account for the water required based on the environment. In other words, shrubs and flowers should be watered at a different rate than turf. Shaded turf may be watered less than turf placed in full sun. Grass type is also influential. Unfortunately, not all sprinkler systems are designed with these considerations as it can be more costly to engineer a system with greater efficiency. TIP: If you don’t currently have a sprinkler system, and are looking to purchase one, beware of the very low bids as some Irrigation Contractors will take short cuts on the items mentioned in an effort to win the business.
Stage I: Gain the most efficiency out of your existing system without impacting the design. All of Stage I is covered in detail in the “Sprinkler Leak” post. But here are the high points.
- Check for leaks in the pressure side of the system. Use your water meter to isolate the leaks in the sprinkler zones.
- Check for leaks in each zone. Most leaks are at the heads; repair and replace the heads and risers as necessary. Make sure you use the same style head and similar nozzle sizes as the one you are replacing. TIP: All the major manufacturers make pop-up heads, its okay to mix brands but if you stick with the same brand, you can always move and change nozzles between existing heads when needed because nozzles are not universal between manufacturers.
- Ensure all sprinkler heads are clean and providing the proper water pattern.
- Adjust the watering duration and times to match the season.
- If your watering durations continue to allow excessive water run off, try changing the watering times to a series of short cycles. For instance, change a single 15 minute cycle to 3 back-to-back 4 or 5 minute cycles. This can allow the water to saturate before the second and third cycle occurs. Typically, I don’t like the short cycle watering strategy, but if you perform it back-to-back, its okay.
- Consider using your system in manual mode only. Watering when only necessary will reduce your water usage substantially.
Stage II: Plan to get wet. This stage requires a bit more effort and the gains achieved may be small, but the intent is to make gradual changes that will increase efficiency without negatively effecting performance. This stage is intended to optimize the system by fine tuning the existing sprinkler heads.
- Look for excessive water accumulation. Not all landscapes require the same amount of water. Unfortunately, when irrigation systems are designed, this fact may not be included in the design. Read the system performance by looking for items such as excessive water, green moss or over saturated ground and plants.
- Fine tune individual sprinkler nozzles. Each sprinkler nozzle has a fine tuning screw on the top of the nozzle allowing you to change the water output. However, when you reduce the flow, you reduce the pattern spray coverage. In some cases, you may completely turn the water off at the nozzle. This is sort of a trial and error exercise, so you may need to make the adjustment and keep an eye on the area for proper coverage. Newer style nozzles may include a water saver disk found under the nozzle to equalize pressure and reduce water usage. Adding or removing this disk will also change the amount of water delivered.
- Parkway Watering: I mention this because this strip of grass found with many older homes is a large source of water waste with automatic lawn sprinklers. Run the zone that waters this area to determine how much waste is occurring. Adjust it as much as you can. If you still have excessive water run off you may consider adjusting the fine tune screw to the off position and either hand water it or let it go brown and just let the rain keep it green By completing Stage I & II, you should be reducing you water waste. You may be able to reduce your watering duration by the fact that you are wasting less water. Before you move to the next step, let the system run for several weeks/months. Monitor the performance and make further adjustments as necessary to the nozzles and watering duration.
After completing Stage I and II let the system run for a couple of months. Monitor the performance and the water usage, make adjustments as necessary. However, if you want to go further, I still have Stage III and IV recommendations. Look for my post next week on “Lawn Sprinkler Efficiency Upgrades Part II“.
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