Here is the biggest forgotten irrigation conservation secret... Don’t use your system! Take a minute to stop laughing… In a severe drought situation, this will obviously not work. In those circumstances you need to work on having no leaks and improving distribution uniformity. However, in most normal situations, you will be amazed at the water that can be saved by simply turning your system off.
Step back and think about your system like an algebra equation. Total gallons = GPM X Minutes ran. If your goal is to reduce the number of total gallons, you have to either reduce the gpm or the minutes used.
Previously we talked about reducing the gpm through more efficient parts and fixing leaks. We also talked about reducing the number of minutes per irrigation event through cycle and soaks and arbitrarily lowering the minutes on the controller. But we can expand this equation and have another variable to manipulate. Total gallons per month = GPM x Minutes ran x cycles. This can be either for the entire system or just a single zone. Cutting your cycles down will have the largest impact on your water conservation efforts and unneeded cycles are, in my opinion, the largest producer of irrigation waste.
Let’s look at a normal week with 4 irrigation cycles set up to run. What will happen if you can get by with only 3? You will save 25%. Not possible? Maybe you can adjust your run times up by a few percent and then eliminate a cycle. The key here is to limit the minutes that water is flowing through the pipes.
It is worth mentioning again that I understand that this does not work for drought stricken turf and landscapes. It also does not work well for people under water restrictions that dictate the days that you can irrigate. But for much of the country, you have full control over these variables. Try it. Irrigation managers tend to view irrigation timing as an art, myself included. However, if you look at it more like a science or math exercise, you will see that there are incredible amounts of savings available. I have trained myself to view it more this way, and so can you.
I will dive into sensors later, but you absolutely must have a moisture based sensor on your system. I prefer combinations of multiple soil moisture sensors combined with a rain sensor, but have at least one sensor that can turn a system off when it is not needed. Again, let’s dive into the math behind saving water. If you get 2 one inch rainfall events during a month, there will be at least 2 irrigation events that are not needed. If you were set on 4 days a week, you will save 12% of your total usage at a minimum. If you were set on 3 days a week you will save 17%. This is on top of any savings you have made through lowering station run times or lowering the gpm per station. Pretty impressive!
If you are reading this, you probably have a sensor and are already seeing this savings. But I have found many of systems at well-known properties that do not have these simple devices. They are cheap and fairly effective. If you don’t have one, go get one today. If you can’t afford one, let me know. I will find a way to help out.
I live in an area of sporadic pop up style thunderstorms in the summer. Rarely can we be promised a rainfall, but we typically get them fairly regularly. The strategy we use is to push off irrigating as long as possible. It is common for us to defer irrigation for a day, and then experience a rainfall the next afternoon before we turn the system on. When this happens, I can actually save two or more irrigation cycles and start to rack up the savings.
Remember to think long and hard before you turn the system on. Can you go another day? If so, wait. You will see some of your more drastic savings this way and best of all, it costs nothing. All you have to do is make a decision. Can you wait? Probably. Try it this summer for a couple of weeks.