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How Can You Capture Rain?

Updated: Mar 13

Rainwater catchment systems are comprised of three parts: collection, containment, connection and distribution. Water distribution includes the connection system that delivers water from the storage container to the area to be watered. Design possibilities will include landscaping and planting design in relation to the rainwater catchment system. There are infinite possibilities for designing an integrated rainwater catchment system, landscaping for water retention and strategic planting design.

It rained 4.5 mm yesterday, or less than 1/4 in. The day before, February 28, it rained 17.1 mm, still less than 3/4 in of rain (according to

In this writing, we are discussing water catchment with the purpose of providing water to gardens.

Water Collection - roof dimensions, slope, volume calculations, downspout locations

-- transfer system brings water to the containment apparatus

--- check re. gutter guards and leaf filters

--- calculate rainfall amount

---- consult precipitation data for historical records

Water Containment - collection infrastructure - tanks, troughs

-- overflow system (where water goes once the tank is filled)

-- makeup system (additive, if there isn't enough rain water)

-- calculate garden size, water requirements, container size

There are many ways for storing rainwater, depending on the location of downspouts, pathways, soil conditions, exposure, and available land. 

Larger containers can become part of garden structure by providing vertical space for climbing plants for vertical gardens.

Our properties in the city will likely not have a large amount of groundspace to hold large water containers. In that case, a series of smaller, more streamlined tanks can be connected to create a larger storage capacity. There are lots of creative possibilities for designing water containment systems.

Rainwater collection can be part of the gutter / downspout system from a roof or deck, it can also be a freestanding feature, filling with rain collected in an inverted umbrella structure.

Water Distribution - gravity feed, pump feed (hand pump, electric), drip line, soaker hose, cascading gardens

-- connection system connects the water in the storage container to the garden area to be watered

--- water lines, faucets, valves

---- in-ground infrastructure - drip lines are flexible plastic tubing with tiny holes or "emitters" that slowly drip water into the soil. Soaker hose 'weeps' water through a porous tube. There are some BPA-free polyurethane models that avoid the issues of rubber and polyethylene combinations.

-- cascading gardens combine sloping ground with terraced gardens and cascading water features

From Harvesting Rainwater for your Home

Garden hose (½ inch): 9 gallons (40 liters) per minute 

Garden hose (⅝ inch):17 gallons (77 liters) per minute

Garden hose (¾ inch): 23 gallons (105 liters) per minute 

Irrigation system: 5.5 gallons (25 liters) for 1 inch (25 mm) of water per square yard (sq. m) 

Garden: assume 0.6 gallons per sq. ft. of garden per week (25 L per sq. meter per week)

Stein, Daniel I. Harvesting Rainwater for Your Home: Design, Install, and Maintain a Self-Sufficient Water Collection and Storage System in 5 Simple Steps for DIY beginner ... (Simple Sustainable Living) (pp. 16-17). RMC Publishers. Kindle Edition. 

Landscape Design - swales, spillways, paths, garden beds

What is a swale: 

A rain garden is designed to collect rain water on the ground to provide moisture to surrounding garden beds.

What is a spillway:

For example, a series of spillway bowls could lead water from the downspout to another part of the garden. There are many possibilities for ideas to create water flow into and out of the garden.

Planting Design - pollinator, drought resistant, food, flowers, indigenous, understory

Water collection, water transfer, water storage, and water distribution designs are integral to planting design, depending on sunlight, soil conditions, slope, and garden size. All of these elements need to be considered as water catchment system design gets underway.

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