rainwater harvesting

The notion of rainwater harvesting may conjure images of old farming landscapes, with cisterns and/or random images of developing countries.

Reality is different, however. Rainwater harvesting has become an operable and functional alternative for many households to conserve water as either a main or secondary supply.  It can viable for both homes and even businesses.

In certain areas of the world, like Australia, Germany, and others, rainwater harvesting is the norm.  And with the size of the green movement in the US right now, we’ll be seeing more around our neighborhoods as well.

Rainwater Harvesting is a Worldwide Practice

Not everyone around the world calls It “rainwater harvesting” but it’s basically the same process all over the world.

rainwater collection worldwide stats

Some other names:

  • Rainwater collection
  • Rainwater catchment
  • Rainwater harvesting
  • Rooftop collection
  • Rooftop water collection

WaterOsmo believes that rainwater harvesting is a perfectly viable option for lots of people out there…even the most urban of areas.  All that you need to do is come up with a system to collect the free-falling water on your roof and gather it in a safe water storage tank.

There are a lot of benefits to rainwater collection but there are two primary reasons to do it:

  • Take control of your own water supply.
  • Drastically cut down on your household water needs.
  • Supply secondary necessities with 100% of water requirements, i.e. potable or landscaping.

What is Rainwater Harvesting?

In the simplest of terms:  Rainwater harvesting is the collecting of run-off water from structures and then storing it for later use.

Traditionally, the process is to:  The free water hits a roof, it collects and channels into gutters and rooftop drainage systems.  Then the water is funneled and guided into a rainwater storage tank or a system of cisterns.

Benefits of Collecting Rainwater

  • Rainwater is relatively clean. Remember, it’s been filtered naturally by the Earth’s hydrological cycle.
  • Free source.
  • Control your water supply if you have a city that has water restrictions.
  • Environmentally responsible, “green” and socially acceptable.
  • Promotes and instills a sense of self-sufficiency and conservation.
  • Better for landscaping and household plants because it is not chlorinated.
  • Reduces runoff and stormwater runoff from businesses and homes.
  • Reduces or eliminates drainage problems and provides FREE water at the same time.
  • Simple technology, simple processes, inexpensive, easy to do.
  • It can be the main water source or a secondary source to municipal water supplies or wells.
  • It can be added to existing homes and businesses or built-in at initial construction.
  • Systems can be simple, single units or modular, larger systems.
  • If you need emergency water, then you have ample sources already stored.

Rainwater Harvesting and Collection Gear

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Is Rainwater Harvesting a Big Deal?

Rainwater harvesting is super important for a lot of reasons.  If you’re looking for a way to increase your water conservation efforts and your running out of ideas and ways to do it indoors, then looking outdoors is the next place to look.


If you’re already using water-conserving toilets, dishwashers, faucets, etc, then you really can’t get much tighter in the home.  Rainwater collection will hugely impact your already stalwart water-saving efforts.

What do People Use Collected Rainwater for?

Basically, you can use rainwater wherever you use tap water.  If you’re drinking it, though, you may want to pass it through another water filtration process.  That being said, it doesn’t MAKE ANY SENSE to flush our toilets or water our lawns with our precious, drinking water.  Rainwater can do as good, or better, job at things we use our faucet water for.

3 Basic Uses for Harvested Rainwater

  • Irrigation
  • Indoor (non-potable use)
  • Whole house (potable use)

Brainstorm some ideas for rainwater use around your house like:

  • Watering lawn and garden
  • Watering indoor plants
  • Hook your rainwater into your sprinkler/irrigation systems
  • Cleaning vehicles
  • Washing dogs and other pets
  • Filling fish ponds, fountains, indoor aquariums (after treatment for fish safety)
  • Swimming pool fill/re-fill
  • Properly filter and disinfect and use it as drinking water

How Much Rainwater Can You Harvest?

It’s a pretty simple calculation for water collection and it goes like this:

1 inch of rain multiplied by 1 square foot is equal to 0.623 gallons.

1” rain x 1 sq ft = 0.623 gallons

You can see how much rainwater you can actually collect during a single rainstorm and if you live in a wet or rainy area then you can gather lots of water all year long.

1,000 sq. ft of roof and 1” of rain collects 623 gallons!

So, if you know your average annual precipitation In your area and the square footage of your roof, then you can easily find out how much water (and money!) you’ll save.

map of us precipitation

What’s the Easiest way to Collect Rainwater?

Okay, so now you want to start harvesting rainwater at your house.  Even though rainwater collecting is an old technology, there have been numerous advancements and innovations to make rainwater collection easier.

We’ll present three ways to collect rainwater below.  The only things that differ amongst the three is the size of the operation, effectiveness, and how it looks in the yard!

Rainwater Harvesting Methods

Rain Barrels

Lots of people use this method and it’s probably the most well-known method of collecting rainwater.  It involves placing a barrel where there is a gutter drop pipe (downspout) and as the water runs through the gutter system and down the spout, it collects in the barrel.

rainwater collecting barrel

You can buy a barrel-like this here.


  • Easy to start doing by most people, at most residences.
  • Don’t want to buy online?  You can buy these at community or home building stores.  Even department stores.
  • Barrels are small and fit into corners.


  • Usual capacity is limited to 50 to 100 gallons.
  • It can overflow and waste an opportunity.

Dry Systems

This is basically a rain barrel system but on a larger scale and usually involves a series of pipes and a system that is made specifically for rain collection.

rainwater harvesting barrel


  • Larger collection capacity.
  • Better suited for drier climates that don’t have but a few, larger rain events.
  • Less complicated system than a wet system and easier to install and maintain.

Wet Systems

This is by far the most complicated and expensive option.  It involves collection pipes underground in order to connect several downspouts from variously located gutters.  The water collects into the underground piping and as the water level rises, it fills the collection tank.


  • Collect water over the entire roofing or collecting surface.
  • Multiple gutters and downspouts involved, increasing the collection volume.
  • The tank can be installed independently of your structure (home or building).


  • More expensive


Rainwater collection is vital for the future of sustainable water resources and true water conservation.  But it can also benefit you, your home, your wallet, and your family on a more personal level.

As the population grows and the stress on municipal and natural water supplies keeps increasing, we need to conscious of anyway to conserve more potable water.

Rainwater harvesting is basically an untapped source of water for homes and communities.