Rainwater Quality: Why Plants Love Rainwater Best

by Jesse (Froehlich) Savou, ARCSA A.P.

Rainwater quality is better for plants than water from any other source. Learn the four reasons why!

Imagine walking through your garden after a fresh rain. Thirsty plants doused in droplets fallen from the sky, their leaves expertly channeling moisture down stalks and into the soil—right to the root zone where it is needed most.

Greens are vibrant, and so are the color-pops of flower petals. The soil is moist and alive. This is a happy garden!

While it might not come as a surprise that there's no water plants love better than rainwater, do you know the four (4) reasons why?

Read on to learn about the water quality benefits of rainwater for garden. Listen to our podcast feature expanding on this topic and more!

Four Rainwater Quality Benefits

YoungPlantsLoveRainwater

Why is rainwater such a preferred water source? There is more than just one reason—in fact there are four!:

1. Rainwater is 100% soft water

Free of the salts, minerals, treatment chemicals, and pharmaceuticals that are found in municipal water, groundwater, and surface water, rainwater is pure hydration. Salts and chemicals build up in your soil over time and these residues are tough on plants. This effect is exaggerated in potted plants where the accumulation is more pronounced.

2. Rainwater is slightly acidic—naturally!

Green gardeners know that most organically grown plants prefer soil pH levels between 5.5 and 6.5. This is on the acidic side of the neutral pH 7, and by nature's design, it is the exact pH range for rainwater. City water, on the other hand, is treated to be alkaline to protect metal pipes from corroding, and can have a pH level upwards of 8.5. Greywater (once-used household water from a laundry machine, shower, or bathroom sink) will start with the same pH as your tap water, but can have a pH as high as 10.5 once it gets to the garden depending on the types of soaps and detergents that are in it. Irrigate with rainwater to flush out your soil and help keep your soil pH in perfect balance ongoingly!

 

3. Stored rainwater contains some organic matter

If collected from your rooftop, rainwater contains traces of organic material. While the water is very clean and should run clear, it has been exposed to anything on your roof. We're not talking about chunks (these get pre-filtered out on their way into properly-designed rain barrels)we're just talking about contact exposure to leaf litter, pollen, bird droppings and the like (which perhaps not surprisingly are great for your plants). A rain barrel hosts a beneficial biology to keep the water alive—literally. It's like a light application of fertilizer every time you water!

 

4. Rain contains nitrates—an important macro-nutrient

Rainwater contains nitrates, the most bio-available form of nitrogen. Nitrogen is one of the three key macro-nutrients that plants need to thrive, necessary for the development of lush foliage. That said, many forms of nitrogen are not actually absorbable by plants. Nitrates, which are made up of nitrogen and oxygen, are formulated by nature for maximum uptake by your plants. Plants typically absorb most of their nitrates from the soil. And where do those nitrates come from? Rain!

Plants have very unique ways of gathering moisture from the air and delivering it to their root zones. Nature's design!
Plants have very unique ways of gathering moisture from the air and delivering it to their root zones. Nature's design!

On a personal note, before I discovered rainwater, I doubted I would ever be able to keep a house plant alive. I had somewhat better luck outdoors in the garden, but little did I know that the potted plants were really suffering from the salt, chemical, and mineral buildup of tap water. Then I learned about watering with rainwater.  Rainwater straight from my rain barrels into a watering can is what I use for my potted plants and nursery starts. A gravity fed drip line allows me to apply rainwater directly to my in-ground garden with no effort at all. And what a difference it makes. Suddenly I have a green thumb... but (shhh, don't tell.... rather, tell EVERYBODY!) : the secret is the water.

Plant health is just one of the many benefits of harvesting rainwater. Click here for a handful of great reasons to collect the rain that falls on your roof!

Environmental Benefits of Rainwater Harvesting + Free Webinar

Enjoy a free webinar on this topic!

Learn the whats, whys and hows of rainwater harvesting with BlueBarrel's founder and owner, Jesse Savou.

(To contextualize the intro, this webinar was given live on April 21st, 2020, the eve of Earth Day's 50th anniversary, and the onset of the global coronavirus pandemic.) Click the image to play recording:

Environmental Benefits of Rainwater Harvesting in Brief

April is Earth Month. What if you could make a big difference just by installing a few rain barrels?

You've heard rainwater harvesting is good for the environment, but if you're like most, you can't explain exactly why.

Here are a few quick points followed by some key details for why rainwater harvesting is absolutely vital for a thriving local ecology, and for the global water cycle!

 

Rainwater harvesting is a great way to:

Environmental Benefits of Rainwater Harvesting

  • Protect your local watershed;
  • Make your garden more resilient in the face of droughts, floods, and fire;
  • Restore the hydrologic cycle;
  • Recharge groundwater;
  • Reduce your carbon footprint;
  • Maintain healthy soils;
  • Keep your garden lush and healthy (which, in-turn, enriches habitat and helps to regulate local temperatures and precipitation);
  • Lessen the impacts of extreme wet and dry spells;
  • Mitigate impacts of climate change;
  • Utilize recycled materials (a given, if you choose BlueBarrel!)

Environmental Benefits of Rainwater Harvesting Explained

Most of us know that rainwater harvesting is good for the environment, but we need a little help articulating why. Here are five major ways you align with Mother Earth when you capture rainwater for on-site use:

drought

1. Reduce your Draw on Stressed Systems

(Conserve Water)

Aging water infrastructure is expensive to update; and groundwater and reservoirs are often overdrawn. When you supply a portion of your own water from the rain that falls on your roof, you reduce your draw on these stressed systems.

2. Restore the Hydrologic Cycle (a.k.a Water Cycle)

(Reduce Stormwater Impacts & Recharge Groundwater)

Environmental Benefits of Rainwater Harvesting

Click to enlarge image

In a natural landscape, approximately 50% of stormwater infiltrates into the ground, hydrating soils and recharging groundwater. About 40% evaporates, and only 10% runs off.

In developed landscapes, by contrast (e.g. our neighborhoods); only 15% infiltrates and a whopping 55% runs off! This is because water can't penetrate hardscape (roads, rooftops, parking lots, etc...).

When you collect rainwater to use in your garden, you reduce stormwater impacts by holding water on-site rather than letting it run off. As you release it later (when the ground is no longer saturated), you allow that water to sink back into the ground where it belongs, hydrating soils, nourishing plants, and recharging the groundwater beneath us. In other words, you restore the broken infiltration link in the hydrologic cycle.  If you've heard the mantra: Slow it, Spread it, Sink it, Store it! that's what we're talking about here (as opposed to Pump it, Pipe it, Pollute it!).

 

Stream ecosystem

3. Protect your Local Watershed

(Reduce Pollution & Erosion)

When rainwater infiltrates onsite, it is filtered naturally by the earth, and is prevented from entering storm drains and surface waters as polluted runoff. Left unmitigated, rainwater sheets off roofs and paved surfaces, collecting contaminants along the way. When stormwater runs heavy, it causes stream banks to erode as well, causing further damage to our sensitive waterways and wildlife habitat. According to the EPA, stormwater runoff is the number one source of pollution in the USA. When you Slow it, Spread it, Sink it, Store it on your site, you prevent this from happening.

 

4. Reduce your Carbon Footprint

(Mitigate Climate Change by Reducing Energy Use)
Footprints on beach

There is a strong nexus between energy and water in our modern world. In the state of California, for example, heating, treating, and transporting water accounts for over 20% of per-capita energy use! When you reduce your reliance on pumped and treated water sources, you contribute to a collective savings in energy at the same time.

Better yet, if you pair your rainwater catchment system with a user-friendly gravity-fed drip irrigation system, you don't need any electricity at all to run your irrigation.

 

5. Increase the Health of Your Garden 

Butterfly in Garden

(Mitigate Climate Change with Healthier Plants & Soils)

It's no coincidence that plants love rainwater better than any other water source. Not only is rain free of the salts, chemicals and minerals found in other water sources; by nature's design it has the perfect pH balance and nitrate delivery, ready for uptake by your thirsty garden.

Benefit from the beauty of a healthy plant and soil ecosystem, while the earth benefits from all that a healthy garden provides... including cleaner air, carbon sink, pollinator habitat, temperature and precipitation regulation, and more!

The Deeper Why: How Rainwater Harvesting Heals the Earth

We just threw a few biggies at you, so let's break down some of these environmental concepts a little more. What do we mean by temperature and precipitation regulation? Here's where we can really start to understand the interconnected nature of Earth's vital systems, and why carbon reductions alone do not address the deepest roots of climate change.

Have you heard of the urban heat island effect? Temperatures in urban areas are significantly warmer than in immediately surrounding natural areas because dark rooftops and pavement absorb extra heat that then radiates back into the environment. The more we can vegetate our towns and cities, the more we will regulate temperatures. Vegetation in urban areas also helps to improve air quality.

And precipitation regulation? Believe it or not, a lush garden will actually make rain. Get this: plants evapotranspirate, meaning they uptake water from the soils, and emit water vapor into the sky, which contributes to cloud formation. Plants also release bacteria that form "water nuclei" that attract water molecules to form rain drops. Plants ask mother nature for a drink, and she provides. Between adding more moisture to the atmosphere and sending up water nuclei to ask for rain, a landscape of lush gardens will summon more rainfall than a parched one.

Just imagine: by tapping into the otherwise-wasted water source that comes from your roof, you can create abundance in your own backyard. If others do the same, we collectively have the power to bring vitality back to an ailing environment.

So What Are You Waiting For?

No need to imagine any longer. With a full understanding of the environmental benefits of rainwater harvesting, you can align with Mother Earth and start collecting rain today. Click here to get started!

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