Irrigation... Questions & Answers
By Paul Schultz - CIC, CLIA, CLT-E,
Certified Water Manager, Irrigation Resource Manager, Cagwin & Dorward
I received a letter from the water district that the water rates are being raised... what can I do to keep my water costs down?
Research has shown that an average of 20% of landscape water is wasted. To keep costs down, focus on reducing this water waste. Since water waste can come in many forms, start by asking for a landscape irrigation audit from your local water district. It is usually free and most, if not all, provide you a written report of their findings so you have a “game plan”. Many are providing water budgets (how much water your site should be using) and rebates. These will help support your efforts to reduce costs.
How do I know if my irrigation system is working correctly?
Walk the site and look for areas that seem overly wet, or dry, and gutters that always seem to have water in them. These can be signs of broken sprinklers, buried pipe that is cracked, or water leaking through irrigation control valves. Look for plant stress and hot spots in the turf. If time permits, walk along with your landscape professional and have them turn on a few “representative stations” and observe coverage. Look for tilted or broken sprinkler heads. Does the pressure seem too weak? Does it seem too high; referred to as “fogging”? Watch for over spraying of water into streets, walkways, or on to walls. These should be corrected to help save money on water, and prevent greater repair costs to buildings and roadways. Also, while a station is on, time how long it takes until the water runs off the area it is intended to water. Then ask the landscaper how long that station is scheduled to run each time it comes on. Excessive run times can be a sign of a need for additional training of landscape personnel.
What are the signs of an overwatered landscape?
There are several signs of overwatering to look for, so here are just a few. Look for soggy turf when you walk on it, algae in the planting beds and along street gutters, stunted tree growth, moss in cracks along the sidewalks, wash out of silt on to sidewalks, and pre-mature erosion of walkways and asphalt. While some of these are items that can be remedied through repairs, most are due to improper irrigation controller programming, incorrect or poorly performing irrigation equipment, or poor irrigation design. Another sign to look for, but it is hard to find if you are not trained to do so, is to look for “poa annua” in your turf areas. It is a fine bladed weed that looks like grass. It has very shallow roots, so if it is still green during the summer heat, it is being watered daily to keep the top layer constantly wet. Real grass has deeper roots and can take advantage of water deeper in the soil that doesn’t dry up as quickly. Too frequent water leads to oversaturated soils, quick run-off, and poor plant health conditions.
I have budgeted money for irrigation upgrades, where should I begin?
Begin with a water district audit, if available, and target the highest water use areas, such as turf. Also, learn about their available rebates. If you are considering upgrading the irrigation controllers to “Smart” type, make sure the installer AND the people who will be managing it are trained, otherwise the results could be disappointing. An untrained person will get frustrated when the landscape shows signs of significant stress and won’t know how to correct the underlying issues. The controller may be “Smart” but, the irrigation equipment in the ground may not be. Poor coverage becomes more obvious when the site is no long being overwatered. Signs of stress could lead to overriding the new controller’s weather based schedules, making it a very expensive standard controller. Check out the California Landscape Contractor’s Association’s, “Certified Water Manager” program to find a certified professional. A standard controller, “Managed smart” can help offset costs for upgrading the irrigation system.
What small scale upgrades can I do that don’t cost much and will give me immediate water and money savings?
Where appropriate, upgrade pop-up sprinkler head nozzles to rotary nozzles. It has been shown to improve coverage by 10 to 20% and reduce water waste. Also, get pressure down, to avoid “fogging” so that sprinkler heads operate at manufacturer’s optimum performance levels, which is 30 psi for sprays and 45 psi for rotors. According to Rain Bird, “every 5 psi beyond this recommendation results in a water loss of 6-8%”. This can be done either at the valve, the head, or the beginning of the system. Also, consider use of bark mulch to reduce evaporation in planting beds. In selecting one that can decompose into the soil over time, it will also increase the water holding capacity of the soil, help nurture the soil food web, and improve root development.
What sort of plants use less water?
Plants can be classified as High, Medium, or Low water use. Annuals and turf are examples of High water use plants. Drought tolerant shrubs or Natives, which use about one third the amount of water, would be considered Low water use plants. There are books available to help identify plants by these main categories. The important thing to remember is that whatever you plan to plant; group your plants by similar watering, soil, and sunlight needs. Plants grouped this way constitute a, “Hydrozone”. The irrigation system should be designed to water each unique Hydrozone separately, so that you are not having balance watering High water use plants in full sun with drought tolerant plants in shade. Something will not survive!
What does it mean to "split a meter"?
Many older sites have only one water meter to track domestic and landscape water use. This makes it difficult to determine how much water is being used for the landscape, and nearly impossible to verify that it is being managed well and to a water budget. To “split a meter” means to have a separate meter, or a sub-meter, to track irrigation related water. It is typically located at the beginning of the irrigation system. It will also help with detecting irrigation mainline leaks underground that would otherwise go unnoticed until bills start spiking.
How do I know how much water I should be using on the landscape?
You will need a, “water budget” to know the right amount of water for your landscape. It is created by measuring a site’s irrigated landscape square footage, by High, Medium, and Low water plant types. Then, this information is adjusted by regional plant climate information, referred to as, “Evapotranspiration” to determine how much water typically leaves plants for your area over a certain time period. This is the water that will need to be replaced by the site’s irrigation system. A hot climate area with a lot of High water plants will use more water than coastal sites with low water use plants. And, even more if the irrigation coverage is poor. Some water districts provide water budgets and may set billing based on it. If no budget is provided, check out http://clca.us/water/hire-certified-water-manager.html for assistance with this and much more.