From the most developed countries to those with almost nonexistent infrastructure, water shortages affect people everywhere. About 70% of the Earth’s surface is covered in water, but 96.5% of the water on our planet is too salty for everyday human usage. Of the existing freshwater, 70% is frozen in glaciers, ice caps and permanent snow. This leaves only 1% of all Earth’s water to meet the needs of the nearly seven billion people occupying the planet. While that might not seem like much, it would be more than enough to go around if more people embraced water conservation techniques.
The next time you curl up with a book to watch the rain pour down outside, think about this: just one inch of rainfall showers an incredible 312 gallons of water onto 500 square feet of the Earth’s surface. That means if the rain falling on a 500-square-foot roof could be collected, the people living under that roof could potentially harvest 312 gallons of water to use until the next rainstorm.
Just think for a moment what this could mean, not only for that family, but for the community and environment as a whole. That’s 312 gallons of water that the family can use for free. 312 gallons of water that did not require energy to deliver to that family, that was not diverted from lakes and rivers by man-made dams.
It’s low-impact, sustainable, cost-effective over time, and aids global water conservation efforts. Want to find out the best and safest way to make rainwater harvesting a part of your household? Read on!
Step 1: Catchment
The first step in setting up a rainwater collecting system is building the catchment area – the place where you collect the water. Although there are a variety of possible surfaces, the roof is the most basic and commonly-used for this purpose. Roofs made from galvanized corrugated iron, aluminum, tiles and slates collect the most water with the least contamination. It is still important, however, to clean the roof regularly so that bird droppings, leaves, dust and other contaminants don’t end up in the collected rainwater. As another precaution against contamination, make sure that any surface you use for collecting rainwater is free of metallic paint or any other type of coating that can affect the taste and color of the water. Also, use mesh to cover the gutters that funnel the water into the storage container.
Step 2: Conveyance
After you’ve got your rooftop catchment set up, you’ll need to put a conveyance system in place. “Conveyance” is how the water flows from the roof into a storage container. This is the trickiest part of collecting rainwater because it plays the largest role in determining the quality of water collected.
When it first begins to rain, the water flowing off of the roof contains some dirt and debris from the surface – no matter how often you clean it. The conveyance system needs to divert the dirty water falling at the beginning of the rainstorm to the ground while allowing the clean water falling later in the storm to collect in the storage container. It may seem wasteful to let some of the rainwater splash to the ground, but remember: you’ll be collecting hundreds of gallons that will more than make up for the dirty water lost at the beginning of the storm.
The easiest way to ensure that only the clean water makes it into the collection tank involves closing a flap over the pipe leading to the storage container. When the water runs clear, open the flap and let the rainwater collection begin. There are also more complex, automatic systems that don’t require monitoring the water running off the roof. No matter what type of conveyance system you opt for, however, you should always use PVC or plastic pipes to ensure that the acidic rainwater does not erode them or release corroded metal into the collected rainwater. Not only does this contaminate the collected water, it also pollutes the soil where the runoff water falls.
Step 3: Storage
The final component of setting up the rainwater collecting system is the water storage tank. The style of tank is completely up to you. Gone are the days of the huge green plastic tub dominating your backyard. Today, people use above- and below-ground tanks made of a wide range of materials such as reinforced cement concrete, ferrocement, plastic, mortar and galvanized iron. The only rule of thumb is to keep your storage tank well-maintained and tightly covered so as to prevent contamination, algae growth and mosquito breeding.
Rainwater harvesting is an easy way to help preserve one of Earth’s most precious resources. The next time it rains, take a look out the window and think about all that possibility falling from the sky.
Explore The Ambler
Shortages are only one side of the story. To learn more about the global water crisis, read Mark’s introduction to the issue of ocean acidification, check in with a ‘retired’ couple working to provide clean water to impoverished Panamanian communities, and learn all about the water conservation techniques being used on Isla Palenque.