Photo of wooden rain barrel by Waldemar on Unsplash
By Mark Banaszak
Recent growing seasons in northwest Michigan have been dry. So dry, in fact, that they are classified as drought by the National Weather Service. This has made gardening a little more difficult, especially if you don’t have easy access to water near your garden.
Our sandy soil often means that water drains quickly, giving plants less time to collect the water they need. Using your residential well can mean long hoses, increased energy use and additional wear on well systems. Drought causes everyone to water more frequently, increasing pressure on available groundwater and increasing pumping costs. It may even lower the water table and reduce water quality.
When precious rain does fall, having a home system to collect and store the water for later use in gardens is both sensible and sustainable. Using rainwater to water gardens has several well-documented benefits. Rainwater is often softer than groundwater and nutrient-rich, which can be good for many plants and the soil. Capturing rainwater can reduce soil erosion because there is less concentrated water runoff.
If you are thinking of using rainwater in your flowerbeds but concerned about watering vegetable gardens with roof runoff, read this comprehensive study found on the website of the Sightline Institute: https://tinyurl.com/n7mcbkts
Rainwater collection is adaptable to your garden’s needs and budget. You can start with a simple system and adjust as needed to adapt to our changing weather patterns. To get started, you only need a roof with a gutter and a storage container.
There is a simple formula to calculate how much water a roof will collect. Multiply the amount of rain in inches by the square footage of the roof by 0.62. The resulting number is the number of gallons captured. For example, a shed with a roof of about 250 square feet can collect 155 gallons of water in a one-inch rain. There is a similar formula to calculate how much water your garden requires. Each square foot of growing area needs about one inch of water per week, so to calculate that, multiply the square footage of the growing area by 0.62. If your garden beds total about 250 square feet, you need 155 gallons of water per week.
The size and placement of your storage container is essential. Many people use repurposed tanks, like IBC tanks or plastic barrels, for rainwater collection. It is important to cover the tank and filter the inflowing rainwater to reduce the chance of clogging the system with leaves or debris or contaminating the water with algae or insects.
In general, the higher you can get your tank in relation to your garden, the better. If you have a rain barrel at ground level, or even just up a foot or two on cinder blocks, you can use it to fill a watering can. Raising your barrel higher helps a lot; even at four or five feet you will have enough for low-pressure drip irrigation, but you can also use a water pump to pressurize your system for larger gardens or distances.
If you set up a system, don’t forget to winterize it to keep it in good shape for next year. To winterize, detach the downspout connection, drain the tank and make sure openings are covered or the tank is turned upside down for the winter.
Even a simple rain barrel system can help you be more independent and better prepared for changing weather patterns. According to Brandon Hoving, a meteorologist and program leader with the Grand Rapids office of the National Weather Service, though the droughts of recent summers may be going away, lower lake levels may continue to affect our water table, so harvesting rainwater is still a good strategy.
Mark Banaszak spent over 30 years as a public school educator, urban community gardener and outdoor enthusiast. Recently, he transplanted his city life to rural Manistee County.
