Harvesting Rainwater Saves Money & Benefits Plants
It’s El Niño season again and the forecast from NOAA’s Climate Prediction Center is that this year’s event is “significant and strengthening.” If you don’t know what El Niño is, it’s when the eastern Pacific Ocean warms and the winds, which normally push the warmer water from east to west, move in reverse direction. This creates significant changes in weather patterns and means record rains this year for Southern California. One of the ways El Niño’s rains will help us is providing a lot of rainwater to harvest. We all need to do our part to conserve and it needs to be a part of our strategy in years to come to save water.
Rainwater harvesting is essentially the accumulation of rainwater, from roof tops or rivers for re-use on-site. There are multiple benefits from rainwater harvesting. First, water rates are projected to increase and every drop of rainwater you collect is a reduction in your water usage and your water bill. It is also free of all the chemicals and additives found in treated city water. Plus, if you’re using rainwater to quench your landscape’s drought-caused thirst, you can water whenever you choose and not just on rationed days.
There are three basic components to any rainwater harvesting system:
- Collection area
- Transportation system
- Storage facility
The first one, the collection area, is wherever the rain doesn’t hit the ground, you can collect it. The most common collection area is your roof. The basic rule is that an average 25-foot by 40-foot roof collects about an inch of rain per hour in moderate rainfall. That’s approximately 600 gallons! Two downspouts can direct 300 gallons of water each into your collection barrels.
The next component is the transportation system, which is made up of the gutters and downspouts around the edges of your home’s roof. They’re usually made from aluminum or plastic, but the material isn’t the important part; it’s the size of the gutters and downspouts that counts.
They have to be big enough to handle the amount of rain coming off of the roof. The typical size is five or six inches wide for the gutters. The five-inch gutters are connected to three-inch-diameter downspouts and the six-inch gutters are connected to four-inch-diameter downspouts. The five-inch gutter/three-inch downspout combination is perfect if your roof is 1,000 square feet or less. Roofs over 1,000 square feet should have the six-inch gutter/four-inch downspout combination.
Filters are the last part of the transportation system. Leaves and debris can clog the downspouts and stop your rainwater harvesting efforts. Screens help prevent this from happening. Those who live in mosquito-infested areas should put a fine-mesh screen, such as an aluminum window screen, over the barrel. This will keep the mosquitoes from getting to the standing water and laying eggs.
The third and final component to the rainwater harvesting system is the storage facility. This is where the rainwater is deposited by the downspouts and where you keep it until you use it. The storage facility is usually a barrel.
Placing the barrels correctly is very important. They should be under a downspout that is close to the areas of your landscape that need the water the most. Dig out an area the size of the cinder block base on which you’ll set your barrels. You should dig to a depth of four inches and fill it with ¼-inch pea gravel; this makes it easier to level the blocks and drain water away from your home’s foundation. Raising the barrels also increases the water pressure from the spigot and makes it easier to get a watering container under it.
What happens if there’s more rain than you have barrel capacity to collect? You can connect the barrels (under the downspouts) to barrels off to the side by using short hoses. This allows you to fill extra barrels and not miss a drop of free water!
Heavier rains may cause overflow from the barrels. This is where the layer of pea gravel comes to the rescue by draining the excess away from your foundation. Alternatively, the extra can either go into additional barrels as mentioned above or you can put an overflow port close to the top of the barrel with a hose that carries the excess to your garden.