2. Rainwater Harvesting: What is it?
Rainwater harvesting is a catch system that stores rainwater in rain barrels or
tanks (above or below ground). The stored water can be used for many
purposes, both potable and non-potable:
Potable (With Filtration System) Non-Potable
Drinking/Tap Watering a Garden and Other
Outdoor Plants
Cooking Toilet water
Washing Dishes Large-Scale Irrigation
Bath and Shower Washing Cars
3. Rainwater Harvesting: How it Works
Rainwater harvesting typically collects rainwater from roofs via a downspout
diverter that connects to a storage system (See Figure 1). In addition to the
diverter, there is also a filter screen which prevents large debris from getting
into the system.
The storage system (See Figure 2)
A hose runs from the diverter to storage.
An overflow hose is also attached to the storage system to divert excess water
away from housing foundations.
A spigot or ball valve are installed at the bottom of the storage systems for
dispensing water.
Storage systems can be easily expanded upon by adding connecting another barrel
or tank.
Figure 1 shows a downspout diverter
which also has a filtration screen inside
the unit.
4. Rainwater Harvesting: How it Works
Diverter connected to downspout Plastic tubing running from the diverter
Plastic tubing connected to rain barrel with
overflow PVC vent that connects to overflow tube
Rain barrel with spigot and plastic overflow tube
pointing away from the house
Figure 2 shows a basic
rainwater harvesting
system.
5. Rainwater Harvesting: History
Rainwater harvesting has been used by many civilizations, dating as far back
as 10 BC (Leung, 2008).
Romans where known to have used rainwater harvesting for watering crops,
consumption, and creating cooler microclimates (Leung, 2008).
Large underground cisterns (see figure 3) were used to prevent the water from
becoming polluted (Hasse, 1987).
It is suspected that rainwater harvesting began to fade out due to the
advancement of routing streams to urbanized areas (Hasse, 1987)
Figure 3 shows an
ancient
underground
Nabataean cistern
used to store
rainwater.
Fahlbusch, 2008.
6. Rainwater Harvesting: Modern Day
Applications and Benefits
USES BENEFITS
• Irrigation
• Drinking/Cooking
• Bathing
• Toilet Water
• Dishwasher
• Outdoor watering
All uses help to:
• Decrease the demand on fresh water
supplies.
• Manage stormwater runoff, pollution,
and erosion caused by it.
• Provide people with a viable solution
to water shortages in areas drought
susceptible areas.
• Decrease annual costs of from public
water use.
7. Rainwater Harvesting: Disadvantages
Disadvantages of rainwater harvesting:
Cannot be used as a primary source of water since it is dependent
on rainfall
Storage limitations
Can become polluted from animal droppings or other roofing
leachate
Requires regular maintenance – especially on large scale
applications
Cost can be somewhat high at first: $200-$23,000 (EFA, 2015),
depending on the size, material used, and type of filtration
system.
8. Rainwater Harvesting: Global
Significance
Global uses for Rainwater Harvesting:
Backup water storage during drought or
natural disaster
Is a viable source of water in arid areas of
the world
Helps to meet global demand for water
Reduces global pollution and land erosion
from runoff
Preserves habitats effected by flooding,
erosion, and pollution
Rainwater Harvesting in Uganda. United Nations
University, 2012.
9. Rainwater Harvesting in Australia
Used for drinking water, outdoor watering, fire water, and waste
water (i.e. toilet and bath)
Used for commercial applications (see figure 4)
Is a viable source of water in a country where water is naturally
scarce
In Australia, 22% of the population owns a rainwater harvesting
system (NSW, 2015).
This helps to significantly reduce public demands on an
already limited fresh water supply.
Figure 4 shows 2 out of 5
rainwater collection
tanks in Australia. Each
tank holds 4 megalitres
of water which is used
for fire and drinking
water. Rhino Water
Tanks, 2015.
10. Rainwater Harvesting in South Korea
Rainwater Harvesting is primarily used as a backup water source during times
of drought and natural disasters (SEI, 2009).
During Monsoon seasons, a years worth of water can be delivered within 3
months (WaterWorld, 2015).
South Korea has offered developers incentives to help alleviate any financial
burdens associated with implementing a rainwater harvesting system.
Builders are allowed an extra 3% of floor space beyond regulations if rainwater
harvesting systems are implemented (Han, 2009).
Pictured is Professor Han, a
major global advocate of
rainwater harvesting.
Professor Han has brought
rainwater harvesting to the
forefront in South Korea
through research and bringing
public awareness
(WaterWorld, 2015).
11. Rainwater Harvesting: Materials
Materials Use/Function
Rain barrel(s) or tank(s) Stores rainwater
Downspout Diverter (see figure 5) Connects to gutter downspout and
diverts water to storage
Hose or Piping Connects diverter to storage and
redirects overflow away from house
foundations
Spigot Dispenses the rainwater
Screen or filter Prevents large debris from entering
storage
Pipe/Hose Straps Secures pipe/hose to house
Hacksaw For cutting downspout
Screw driver/Drill For securing diverter and hanging
pipe straps
Zip Ties For securing the tube to downspout
Box Wrench For tightening the nut on the inlet
attachment
Figure 5 shows a modified stock
photo of the Fiskars diverter from
Amazon.com.
12. Rainwater Harvesting: Action Plan Phase I
Connecting the downspout diverter to gutter
system:
Measure the length of the diverter and then subtract 4 inches.
Take this measurement and mark it on the downspout gutter where you
plan to attach the diverter.
It is recommended to detach the downspout gutter to make the next
step a little easier.
Using the measurements from before, cut into the downspout using a
hacksaw. Be sure to use caution after making the cuts. Most gutters
are made out of aluminum and will have a sharp jagged edge after it’s
cut.
Once the downspout is cut, fit the diverter to each end. Reinstall the
downspout if necessary. Make sure the diverter is where you want it
and then secure the diverter with screws.
13. Rainwater Harvesting: Action Plan Phase I
Preparing the rain barrel or tank:
Using a spade drill bit, cut a hole in the top lid
The hole’s diameter should be slightly less than the inlet
attachment’s diameter
Note: Inlet hole can be cut on the side of the barrel but
must be as high as possible.
Insert the inlet through the top of the rain barrel and tighten
the nut using a box wrench
Repeat the same steps when installing an overflow tube, except
the outlet hole should be located on the side of the barrel and
slightly below the level of the inlet hole.
Drill a hole on the side, towards the bottom of the barrel for
the spigot. Be sure to use a spade bit which is slightly smaller
than the diameter of the spigot.
14. Rainwater Harvesting: Action Plan Phase I
Attaching the hose from the diverter to
the rain barrel:
Measure the distance from the diverter
to where you plan to put the rain barrel
Use this measurement to pick out the
right hose length
Run the hose down the downspout and
secure using zip ties
Connect the hose to the rain barrel
inlet
Use duct tape to wrap around the
inlet if the hose is loose
A hose clamp can also be used to
make an even tighter connection
15. Additional notes and materials:
The overflow hose should be pointed away from
the house’s foundation.
Landscaping rocks can be used around the rain
barrel and overflow hose to prevent erosion.
The rain barrel should be below the Diverter and
raised up off the ground to allow fill clearance.
The rain barrel should have a cover to prevent
contaminants and insects from getting into it.
A ball valve can also be used in place of the spigot
in order to allow the attachment of a garden
hose. Note: Rain barrel should be higher than the
watering areas for achieving enough pressure.
Rainwater Harvesting: Action Plan Phase I
16. Rainwater Harvesting: Action Plan Phase II
Increase the amount of storage capacity
Install rain barrels at a higher point in order to increase water
pressure for outdoor uses
Connect an electric pump to the rainwater harvesting system which
will be solar powered
Add Pex plumbing for interior use
Plumbing will run from the water source, to the pump, and then to two
toilets
Ball valves will be installed with each toilet for switching from rainwater
to municipal water
17. Rainwater Harvesting: Conclusion and Goals
The purpose of implementing a rainwater harvesting
system:
Decrease the amount of runoff and pollution that comes from our
property
Cutback on our municipal water use for both indoor and outdoor
uses
Significantly decrease the amount of wastewater that comes from
our toilets and dishwasher
Lessen the strain placed on fresh water supplies
Become more self-sufficient and rely less on public systems
Spread knowledge and awareness to friends, family, and neighbors
who inquire about the system
18. References:
Energy and Environmental Affairs. (2015). Demonstration 5: Rainwater Harvesting. Retrieved May 22,
2015, from http://www.mass.gov/eea/agencies/dcr/water-res-protection/ipswich-river-
watershed/demonstration-5-rainwater-harvesting.html
Fahlbusch, H. (2008). Water in Antiquity, an introduction. Retrieved June 16, 2015, from
http://www.romanaqueducts.info/webteksten/waterinantiquity.htm
Han, M. (2009). Rainwater Harvest System – Star City, Seoul. Retrieved June 12, 2015, from
http://www.fbr.de/fileadmin/user_upload/files/Englische_Seite/Han_WS_1_2009_engl_webseite.p
df
Hasse, R. (1987). Rainwater Reservoirs above Ground Structures for Roof Catchment. Retrieved June 12,
2015, from
http://wgbis.ces.iisc.ernet.in/energy/water/paper/drinkingwater/rainwater/introduction.html
Leung, J. (2008). Rainwater Harvesting 101. Retrieved May 23, 2015, from
http://www.grownyc.org/files/osg/RWH.how.to.pdf
NSW. (2015). Semi-arid woodlands (shrubby sub-formation). Retrieved June 12, 2015, from
http://www.environment.nsw.gov.au/threatenedSpeciesApp/VegFormation.aspx?formationName=S
emi-arid woodlands
Rhino Water Tanks. (2015). Commercial Water Tanks - Corrugated. Retrieved June 16, 2015, from
http://www.rhinotanks.com.au/index.php/commercial-water-tanks/commercial-water-tanks-
corrugated/
United Nations University. (2012). Rainwater and Health in Developing Countries: A Case Study on Uganda
- United Nations University. Retrieved June 16, 2015, from
http://unu.edu/publications/articles/rainwater-and-health-in-developing-countries-a-case-study-
on-uganda.html
WaterWorld. (2015). South Korea. Retrieved June 17, 2015, from
http://www.waterworld.com/articles/wwi/print/volume-27/issue-4/editorial-focus/stormwater-
management/south-korea.html
