United States Department of Agriculture
Forest Service
Tech Tips
National Technology & Development Program • Facilities • November 2013 • 7300 • 1473–2307P–MTDC
Roof-Based Rainwater Harvesting Basics
Damien Hoffman, Project Leader and Kathleen C. Marks, Civil Engineer
Highlights…
• Installing a rainwater harvest
system can be advantageous
both ecologically and
economically.
• Limited or seasonal ground
water supplies can be
augmented, and flow to
storm water drains and
nonpoint source pollution can
be reduced.
• This tech tip includes
calculation examples for a
rainwater catchment area,
as well as collection and use
tracking.
R
ainwater harvesting is the act of collecting and storing rainwater for use. Harvest systems vary from
projects requiring complex engineering to simply
placing vessels (such as pots) in a location where rainwater
flow is focused. Depending on the intended use and expected
harvest amount, system components can vary greatly in
design, size, and cost.
Archeological evidence shows humans have been collecting rainwater for several thousand years. Early European
settlers of the Great Plains harvested rainwater as did Native
American tribes in the Southwest before them.
This tech tip outlines roof-based rainwater harvesting
basics, from estimating potential harvest amounts to system maintenance and care. The project focused on harvesting rainwater for irrigation and included the installation of
a rainwater harvest system at the Missoula Technology and
Development Center (MTDC). Harvesting potable water may
require following additional State laws and regulations as
well as the use of additional filtration equipment.
For additional information, contact: USDA Forest Service, MTDC; 5785 Hwy. 10 West; Missoula, MT 59808–9361.
Phone: 406–329–3900; fax: 406–329–3719; email: wo_mtdc_pubs@fs.fed.us
Why Harvest Rainwater?
Installing a rainwater harvest system can be advantageous both ecologically and economically. Some of these
advantages include:
• Rainwater is free, and a harvest system can be
inexpensive.
• End use is close to the source.
• Limited or seasonal ground water supplies can be augmented.
• Rainwater has a nearly neutral pH and is free of salts,
minerals, and natural and manmade contaminants, so
it is suitable for livestock.
• Flow to storm water drains and nonpoint source pollution are reduced.
• Utility bills are reduced by staying off the grid.
• The cost of drilling wells and installing large, expensive pumps is avoided.
Federal Agency Requirements
Executive Order 13514, section 1, requires Federal agencies to “increase energy efficiency; measure, report, and
reduce their greenhouse gas emissions from direct and indirect activities; conserve and protect water resources through
efficiency, reuse, and storm water management.”
More specifically, the Forest Service Handbook 7309.11,
chapter 70, <http://www.fs.fed.us/im/directives/fsh/7309.11
/7309.11_70.doc> requires all new Forest Service regional
offices, district offices, supervisor’s offices, visitor centers,
and research offices/labs (more than 10,000 or more gross
2
square feet) to be registered and certified at the Silver certification level under the Leadership in Energy and Environmental Design (LEED) rating system. Rainwater harvest systems
apply toward LEED certification.
Private-Sector Financial Incentives
Many State and county governments offer financial
incentives for new buildings with rainwater harvest systems.
States with incentives include Arizona, New Mexico, Ohio,
Oregon, Texas, and Washington. These incentive programs
are always changing. Before installing a rainwater harvest
system, be sure to inquire about incentive programs that may
apply to you.
For more information on financial incentives and
resources, visit “Rainwater Harvesting for Drylands and
Beyond” at <http://www.harvestingrainwater.com/rainwater
-harvesting-inforesources/water-harvesting-tax-credits/>.
Is Rainwater Harvesting Legal in Your Area?
A good starting point for learning about State rainwater
harvesting laws is found at <http://www.harvesth2o.com
/statues_regulations.shtml>. If this Web site indicates there are
no laws restricting rainwater harvesting, contact your local and
State water law officials to verify that you understand and can
comply with current laws. Before MTDC installed a rainwater
harvest system, we consulted with State and local Department
of Natural Resources and Conservation officials.
Planning a Roof-Based Rainwater
Harvest System
There are several things to consider if you plan to install
a rainwater harvest system:
• Is rainwater harvesting legal in your area?
• Is it mandatory?
• How much rainwater can be harvested?
• What will the system cost?
• What roof surface materials work best?
• Where can these materials be purchased?
• How will the system be installed and maintained?
How To Estimate Rainwater Harvest
To estimate the amount of rainwater that can be harvested at your location, you need to know local monthly and
yearly precipitation averages and your catchment area (horizontal “footprint” of the rainwater capture surface) in square
feet. With this information, you can estimate your rainwater
harvest potential and purchase equipment that will best serve
the needs of your location. Excel spreadsheets that will help
you with your calculations are in the appendix. Also, you
can download a fillable spreadsheet that will self-populate at
<http://www.fs.fed.us/eng/pubs/pdfpubs/pdf14732307
/documents/h2otracking.xlsx>.
Finding Precipitation Data for Your Location
The National Oceanic and Atmospheric Administration
(NOAA) Web site <http://www.weather.gov> provides data on
monthly and yearly precipitation averages for specific locations.
Click the Organization tab (in the blue bar across the top
of the Web page), click the weather office that is closest to the
project location in your region. On the left navigation pane
under climate, click Local. Click the NOWData tab. For product, select Monthly avgs/totals. For location, select the city closest to the project location. For variable, select Precipitation. For
year, select 1981-2010. For view, click GO. These choices provide a precipitation average using nearly 30 years of data.
The data returned will look similar to table 1.
Table 1—Historical monthly precipitation data for most locations in the United States can be found on the National Oceanic and Atmospheric
Administration (NOAA) Web site.
3
Rainwater Harvest Example
Missoula, MT, has a historical average of 2 inches of precipitation in May (see table 1). A simplified catchment
area for the MTDC example is two rectangular roof areas (figure 1). Roof A is 16 feet wide by 37 feet long. Roof B is
19.5 feet wide by 64 feet long.
• Footprint: Roof A + Roof B = 592 square feet +1,248 square feet = 1,840 square feet
✧✧ Roof A: 16 feet x 37 feet = 592 square feet
✧✧ Roof B: 19.5 feet x 64 feet = 1,248 square feet
• Average May precipitation in feet: 2 inches ÷ 12 inches/foot = 0.167 feet
• Expected average harvest volume in cubic feet: 1,840 square feet x 0.167 feet = 307 cubic feet
• Cubic feet to gallons: 307 cubic feet x 7.48 gallons/cubic foot = 2,296 gallons
Based on precipitation averages about 2,296 gallons of rainwater may be collected during May.
Add the average rainwater collection gallons for each month to determine the average annual rainwater harvest.
If you are in a region with seasonal temperatures below freezing and don’t plan on installing heating elements, you
should exclude months with freezing temperatures from your total harvest potential and size your system accordingly.
Calculating the Catchment Area
Rainwater can be collected from any roof with a slope
that drains to a common area (downspout, etc.). Rainwater can
be collected from all or part of the roof area of a building. The
roof catchment area is not the total surface area of the roof,
but rather the horizontal area covered by the roof as seen from
an aerial view (figure 1). To calculate the footprint of a rectangular roof, measure the horizontal length and width. Multiply
the length times the width to determine the effective area for
rainwater collection.
Roof A
Roof B
Tank
Figure 1—Google Earth image of
Missoula Technology and Development Center with the catchment
area and tank location highlighted. —© 2012 Google
4
Steps for Estimating Monthly Rainwater Harvest
Averages
1. Use a precipitation average (in inches) for any month
of your precipitation data and divide that number by
12 to convert the precipitation average into fractions
of a foot.
2. Multiply the roof footprint (in square feet) by the result
from step 1 to determine the estimated average volume
in cubic feet of rainwater harvested from that month.
3. To convert your volume from cubic feet into gallons,
take the cubic foot calculation from step 2 multiplied
by 7.48 gallons per cubic foot (7.48 gallons = 1 cubic
foot of water). The resulting number is the estimated
average in gallons of harvested rainwater, assuming
100 percent of the water that falls on the catchment
area is collected.
Some controllable elements of a system that maximize
harvest potential include catchment surface type, adequate
gutters and downspouts, installation of leaf and debris strainers, and a properly sized tank. Catchment surfaces (asphalt,
cedar, metal, etc.) have different physical characteristics that
significantly influence catchment efficiency. Adequate gutters
and downspouts prevent spillover. Leaf and debris strainers
help maintain a cleaner flow of rainwater. A properly sized
tank assures little or no rainwater is wasted due to overflow.
A manometer allows visual monitoring of the water level
in the tank. A manometer is a clear tube that is attached to
the tank above the overflow (figure 2) and at or below the
outlet valve (inset). The water level in the tube is equal to the
water level in the tank, providing a clear indication without
opening the tank. The manometer is an effective, simple tool
Catchment Efficiency and Water Use
Monitoring
When rain falls and lands on the catchment surface, a
portion is retained by the surface (roofing material) before
runoff occurs. Catchment efficiency is the percentage of precipitation that hits the catchment area (footprint) and subsequently flows into the tank.
Certain characteristics of weather, such as relative
humidity and temperature, can affect catchment efficiency.
These characteristics can be included when sizing a harvest
system, but may not be necessary if there is an alternative
water source. Calculating these characteristics is only prudent
when stringent accuracy is desired.
Water level in
manometer
Figure 2—A manometer that
is attached to the tank at two
locations shows the water level.
Inset shows lower location.
Rainwater Collection and Use Tracking Example
For vertical cylindrical tanks, volume = π x r2 x h. Pi (π) = 3.14, radius (r) = ½ tank diameter, and h = change in
water level height. If the manometer has a water level height difference of 1 inch and the tank diameter is 64 inches, the
calculation is as follows.
• 3.14 x 32 inches squared x 1 inch = 3,215.4 cubic inches
• 3,215.4 cubic inches x (0.00058 cubic feet/cubic inch) = 1.86 cubic feet
• 1.86 cubic feet x (7.48 gallons/cubic foot) = 13.9 gallons difference
13.9 gallons of water were used.
5
and an inexpensive way to measure the collection and usage
of harvested rainwater. Assuming a vertical cylindrical tank,
the change in height of the tank’s water level (measured in
inches) can be multiplied by the surface area of the tank to
keep track of volume collected or volume used.
A flowmeter is another tool that tracks usage. The Water
Saver (figure 3) from AbsolutelyNew, Inc., is a usage meter
that has a large LCD (liquid crystal display) screen and can
be found at most hardware stores for about $25. It is accurate
to within ±10 percent for flows more than 0.5 gallons per
minute (GPM). If the system uses pumps and meter accuracy
is important, a more accurate flowmeter can be added.
Figure 3—An inexpensive flowmeter is installed to
track water use.
6
Estimated Usage
Understanding water usage trends helps plan a system
that will operate more efficiently through monthly and seasonal variations in precipitation. Usage varies with activity.
The most common use for harvested rainwater is watering
landscapes or gardens. The USDA Natural Resources Conservation Service <http://www.nrcs.usda.gov> recommends
watering lawns with 1 inch of water per week, except during hot weather when the recommendation is 1 inch of water
every 3 days. For example, May in Montana is cool with
scattered precipitation, so watering once a week usually is
sufficient. However, watering three times a week in July may
be necessary. Required watering frequencies also depend on
soil type and vegetation type. Generally, soil that is sandy
requires more frequent watering than soil containing clay and
loam. Similarly, native plants adapt to local rainfall and do
not require a lot of supplemental irrigation, while vegetables
or turf grasses require more irrigation.
Because weather conditions are unpredictable, in any
given month your tank may be overflowing or empty. Estimate rainwater harvests based on historical monthly precipitation averages and, if possible, size your system to allow for
some variation.
Calculating How Much Water You Need
If you are currently irrigating the area you want to convert to rainwater irrigation, you can estimate the amount
of water (in inches) used to irrigate your area. Place a cylindrical can (for example, a tuna can) on the ground, turn on
your sprinkler, and water as usual. By monitoring the depth of water in the can, you can calculate how much water is
needed to keep vegetation healthy. If the area is not currently irrigated, follow the County Extension office or other
local expert recommendations.
To calculate the estimated usage in gallons per week, multiply the square footage of the irrigation area times the
inches of water required each week to obtain the required volume. Then, multiply the volume by 7.48 gallons per cubic
foot to determine the estimated number of gallons of harvested rainwater that will be drawn from the tank each week.
Example: The MTDC irrigation area is 224 square feet. About an inch of irrigation water is required each week.
• 224 square feet x (1 inch x (1 foot/12 inches)) x 7.48 gallons/cubic foot = about 140 gallons.
About 140 gallons of water are needed per week.
Sizing the System
ment efficiency is less than 100 percent, we rounded the
estimated harvest amount to 1,800 gallons (about 80 percent
efficiency). The estimated water usage per week is 140 galOne way to calculate potential rainwater capture and irri- lons, or 560 gallons per month. June will be similar. However, much less water can be harvested during July, August,
gation water demand is to set up an Excel spreadsheet, such
as the example at <http://www.fs.fed.us/pubs/htmlpubs/htm and September.
Carefully consider the operating requirements when deter12732312/documents/h2otracking.xlsx>. This spreadsheet
can help you plan your system and monitor rainwater harvest mining the size of tank to purchase. If alternative irrigation
sources are available, you will have more flexibility in sizing
amounts and amounts used.
the tank. If a rainwater collection system is the only source
of irrigation, you may want to purchase a larger tank (or several tanks) to offer more capacity for supplying water during
months with lower precipitation. A tank capacity of two or
Tank
more times the watering volume required may be necessary to
Based on historical precipitation averages and the size
of the catchment area, MTDC’s system should average about ensure an uninterrupted watering schedule.
2,244 gallons of harvested rainwater in May. Because catch-
7
Gutters and Downspouts
Sizing your gutters and downspouts appropriately
increases collection efficiency. Gutters and downspouts that
are too small for the catchment area may lead to spillover,
which decreases catchment efficiency. Multiple downspouts
leading to the tank or larger gutters and downspouts increase
water transport capability. Gutters that are professionally
installed should be sized appropriately for your collection area.
Resources, such as <http://www.egutter.com>, provide sizing
charts and documents to assist you in sizing your gutters.
vertical drop. If the flow or pressure is not sufficient to meet
your needs, install a pump at the base or near the tank to push
water to your irrigation area. Generally, small pumps for this
type of use “push” water, rather than “pulling” it. You need
the pump close to your water source.
Purchasing Equipment
There are many rainwater harvest equipment suppliers
across the United States. When purchasing the tank, shop
Pump
locally to take advantage of local service capabilities and to
A system without an adequate vertical drop from the
avoid shipping costs. Reducers, pumps, valves, and hoses can
tank to the irrigated area or that has significant friction loss
in the supply line may require a pump to achieve the required be purchased at most hardware or plumbing supply stores.
water pressure to operate the irrigation system. Water gains 1 Gutters and downspouts can be purchased at most building
pound per square inch (PSI) of pressure for every 2.31 feet of supply stores.
Gravity-Fed Pressure Versus a Solar-Powered Pump
The first system MTDC installed was gravity-fed using an
elevation change of 10 feet from the tank to the end-use location,
but the gravity-fed pressure was insufficient. The friction loss
in the 5⁄8-inch hose over 300 feet negated the pressure provided
by elevation. The solution was a solar-powered pump purchased
from Solar Power Solutions <http://www.free-water-lawn-garden
.com/> for about $300 (figure 4). The pump system can be fully
automated, provide 50 PSI, and run for 30 to 45 minutes per
4-hour charge. Another possible solution is a larger hose (1½ or 2
inches) that may provide more flow and pressure.
8
Figure 4—A solar-powered water pump provides a
3-gallon-per-minute flow rate.
Installing the System
Tank and Foundation
Determine if there is adequate drainage and support for
the weight of a full tank before placing the tank at the desired
location. Design the tank foundation carefully. If the foundaThe three basic components of a rooftop rainwater hartion is inadequate, the tank may settle unevenly. In this case,
vest system are gutters, a tank and foundation, and a tank
you will need to drain the harvested water and fix the proboverflow.
lem—an avoidable waste of water, time, and materials.
A foundation may not be necessary for smaller tanks.
Tanks made of wood should be elevated to avoid direct contact with the ground, increasing the tank’s lifespan by slowGutters
To decrease the probability of rain overflowing the gutter ing rot and decay.
If you elevate a tank, be sure the materials are strong
system, “The Texas Manual on Rainwater Harvesting” sugenough to support the weight of a full tank. An elevated
gests consulting a gutter supplier if your catchment area has
one or more roof valleys. The document also recommends that tank also helps gravity-fed irrigation systems. Increasing the
height of the tank increases water pressure and flow at the
gutters be “installed with slope towards the downspout; also
outlet. For larger elevated systems, an engineer can design or
the outside face of the gutter should be lower than the inside
recommend a support system to ensure the tank won’t colface to encourage drainage away from the building wall.”
lapse, settle, or tip. The weight of the water poses a significant safety concern.
Example of How To Stabilize a Water Tank
The MTDC tank holds 1,000 gallons. When full, it weighs
over 8,300 pounds. Because of the weight of the tank and soil
type, the bearing surface the tank rests on was stabilized by constructing a tank pad (figure 5). The pad prevents the tank from
shifting and provides drainage around the tank. The pad was constructed by digging an 8- by 8-foot hole 6-inches deep and placing
lightweight geotextile (more commonly known as weed fabric or
contractor fabric) over the excavated area. To complete the pad, we
covered the geotextile with 6 inches of compacted ½-inch-minus
crushed gravel.
Figure 5—A tank pad increases drainage and prevents the
tank from shifting.
9
Overflow
A tank overflow (figure 6) ensures that a full tank won’t
cause water to back up the downspout and cause a weight
overload that may collapse the gutters. An overflow can be
as simple as a hole in the top of the tank. A hose or pipe that
directs excess water away from the tank prevents pooling,
erosion, and flooding. An overflow should be at least as large
as the tank inlet to allow an equal amount of water to flow
out as in.
Figure 6—An overflow system directs water away
from the tank foundation.
10
System Maintenance
You may want to install gutter guards or a leaf guard on
the downspout if your rainwater harvest location is near trees or
other tall vegetation. Preventing the gutters and tank from accumulating debris will increase collection efficiency. If you install
a debris guard, cleaning and maintenance will be required as
often as vegetation collects. In addition, fine mesh filters should
be used to ensure debris doesn’t clog the hose when drip line or
soaker hose are used. Mesh filters must be flushed regularly.
Winterize your system each fall if you are in a region with
freezing temperatures and you don’t want to install heating
elements for year-round collection. Failure to winterize a tank
may result in a cracked tank, hoses, valves, or pump. Follow
these easy steps to winterize your rainwater harvest system.
1. Disconnect the downspout extension from the tank
and reconfigure the downspout to reach the ground.
Direct water away from buildings or areas that may
become damaged.
2. Disconnect the hose and pump from the tank outlet
and allow the tank to drain.
3. If the tank is small and the outlet is above the bottom
of the tank, open the tank lid and flip the tank over to
drain any residual water.
4. Wash any remaining debris out of the tank.
5. Close the lid and plug any holes that might allow animals or insects in. Leave the outlet open to drain any
water that may inadvertently enter the tank. Cap the
drain line end with metal screen held in place with
a hose clamp. Leave the valve open so no water can
pool in the valve and cause damage.
6. If possible, move the tank to storage. If the tank is left
outside, secure it. Without water to weigh it down, the
tank could blow away during severe weather.
7. If possible, move the pump to storage. Ensure that no
residual water remains in the pump and that no water
can enter the housing. If the pump must be left outside, use an insulated pump house or other protective
shelter to protect the pump.
Summary
When you understand State and local laws and regulations
concerning rainwater collection systems, planning a system to
fit your needs (figure 7) is fairly easy using the Excel spreadsheets available in the appendix and at <http://www.fs.fed.us
/eng/pubs/pdfpubs/pdf14732307/documents/h2otracking
.xlsx>. System costs vary based primarily on the size and complexity of the system. Purchasing system components locally
may decrease costs by decreasing or eliminating shipping and
handling fees. If you depend on your system as your sole source
of irrigation, plan your storage needs to provide a buffer for
below average seasonal precipitation. Using water collected
through rainwater harvesting to irrigate can reduce utility bills,
provide a water source without the high cost of drilling wells or
purchasing pumps, reduce nonpoint source pollution, augment
limited or seasonal ground water supplies, and increase your
awareness of water use.
Web Resources
Forest Service Handbook: Buildings and Related
Facilities
<http://www.fs.fed.us/im/directives
/fsh/7309.11/7309.11_70.doc>
GuttersDirect.com LLC
<http://www.egutter.com>
HarvestH2O.com: Regulations and Statutes
<http://www.harvesth2o.com/statues_regulations.shtml>
National Oceanic and Atmospheric Administration:
National Weather Service
<http://www.weather.gov>
Rainwater Harvesting for Drylands and Beyond:
Financial Incentives and Resources
<http://www.harvestingrainwater.com
/rainwater-harvesting-inforesources
/water-harvesting-tax-credits/>
Rainwater Harvesting Systems for Montana
<http://www.msuextension.org/publications/Agand
NaturalResources/MT199707AG.pdf>
Solar Power Solutions
<http://www.free-water-lawn-garden.com>
The Texas Manual on Rainwater Harvesting
<http://www.twdb.texas.gov/innovativewater/rainwater
/doc/RainwaterHarvestingManual_3rdedition.pdf>
Figure 7—The People’s Garden at Missoula Technology and Development
Center is irrigated by the rainwater harvest system.
11
Appendix
Example Tracking Sheet
12
MTDC Rainwater Harvest System Worksheet
MTDC Rainwater Harvest System Worksheet
Monthly Precipitation Data
Month
January
February
March
April
May
June
July
August
September
October
November
December
Note:
Precipitation
ft = foot
in
ft
ft2 = square foot
1.06
0.77
0.96
1.09
1.95
1.73
1.09
1.15
1.08
0.83
0.96
1.15
0.09
0.06
0.08
0.09
0.16
0.14
0.09
0.10
0.09
0.07
0.08
0.10
ft3 = cubic foot
gal = gallon
in = inch
Horizontal
length (ft)
Horizontal
width (ft)
Area Subtotal
37
64
16
19.5
592
1248
Roof Footprint
Area
Area A
Area B
Total Footprint
in3 = cubic inch
PSI = pounds per square inch
wk = week
mo = month
lbs = pounds
Equations
(ft2)
1840 ft2
Expected Precipitation Volume
Month
January
February
March
April
May
June
July
August
September
October
November
December
Precipitation Volume
ft3
gal
162.5
118.1
147.2
167.1
299.0
265.3
167.1
176.3
165.6
127.3
147.2
176.3
1215.7
883.1
1101.1
1250.2
2236.5
1984.2
1250.2
1319.0
1238.7
952.0
1101.1
1319.0
Volume
Note:
Variable name
Constant pi
Radius
Height
Conversion
Conversion
Total Volume
Value
3.14
32 in
45 in
0.00058 ft3/in3
7.48 ft3/gal
pi = mathematical constant of 3.14
r2 = radius squared
h = height
144691.2 in3
83.73 ft3
626.3 gal
13
Page 1 of 1
MTDC Rainwater Harvest System Worksheet (continued)
MTDC Rainwater Harvest System Worksheet
Change in Volume of Water
Variable name
Constant pi
Radius
Height 1
Height 2
Value
3.14
32 in
44 in
45 in
3215.4 in3
Change in Volume
1.86 ft3
13.9 gal
Irrigation Area
Area
Area 1
Area 2
Total Irrigation Area
Estimated Usage
Variable name
Irrigation Area
Watering
(Amount/Cycle)
Cycles/Week
Conversion
Length (ft)
Width (ft)
Quantity
7
4
8
Area Subtotal
(ft2)
224
0
224 ft2
Value
224 ft2
1 in
1
7.48 ft3/gal
140 gal/cycle
Total Usage
140 gal/wk
605 gal/mo
Note:
Pressure
Variable name
Elevation Difference
Conversion
Total Pressure
Total Weight
Variable name
Weight of Tank
(Empty)
Capacity
Conversion
Total Weight
The elevation difference is the difference from the water level in the tank to the
elevation of the irrigation area. As a quick rule, water gains 1 PSI for every 2.31
ft of elevation change. This does not take into account any pressure losses due
to friction in the pipe, fittings or other losses.
Value
8 ft
2.31 ft/PSI
3.5 PSI
Value
700 lbs
1000 gal
8.35 lbs/gal
9050 lbs
Page 1 of 1
14
About the Authors
Damien Hoffman is a multidisciplinary project leader
at MTDC for the fire, recreation, and engineering programs.
He began work in 2004 as a Web development assistant.
After Hoffman received a bachelor’s degree in wildlife biology from the University of Montana in 2006, he became the
MTDC webmaster. Hoffman is the cache coordinator for
the National Visitor Use Monitoring program. He also has a
bachelor’s degree in sociology from the University of Minnesota-Morris.
Kathleen C. Marks is a multidisciplinary project leader
at MTDC for the facilities and environmental compliance
and protection (ECAP) programs. Marks began work in 2010
after she received a bachelor’s degree in civil engineering
from Montana State University.
15
Library Card
Hoffman, Damien; Marks, Kathleen. 2013. Roof-Based
Rainwater Harvesting Basics. 1473–2307P–MTDC. Missoula, MT: U.S. Department of Agriculture, Forest Service,
Missoula Technology and Development Center. 16 p.
Federal agencies are required to conserve and protect
water resources. Rainwater harvesting is one way to make
the most of what nature provides. In the United States, many
State and county governments now offer financial incentives
to encourage wise use of water.
For additional technical information, contact MTDC:
USDA Forest Service
Missoula Technology and Development Center
5785 Hwy. 10 West
Missoula, MT 59808-9361
Phone: 406–329–3900
Fax: 406–329–3719
A rainwater harvest system needs careful planning and
installation. This report has simple instructions for calculating a roof catchment area and estimating the average rainwater
harvest. This information can be used to design a system to fit
your location. Additional installation details also are included.
Keywords climate change, Executive Order 13514, footprints, gravity-fed pressure systems, gutter guards, manometers, National Oceanic and Atmospheric Administration,
natural resources, NOAA, precipitation, safety at work, solar
power, solar powered pumps, solar-powered pumps, sustainability, water conservation
Electronic copies of National Technology and Development documents are available on the Internet at:
http://www.fs.fed.us/eng/pubs
Forest Service and Bureau of Land Management employees
can search National Technology and Development documents, CDs, DVDs, and videos on their internal computer
networks at:
http://fsweb.mtdc.wo.fs.fed.us/search/
http://fsweb.sdtdc.wo.fs.fed.us/
The Forest Service, an agency of the U.S. Department of Agriculture (USDA), has developed this information for the guidance of its employees, its contractors, and its cooperating Federal
and State agencies. The Forest Service assumes no responsibility for the interpretation or use of this information by anyone except its own employees. The use of trade, firm, or corporation names
is for the information and convenience of the reader. Such use does not constitute an official endorsement or approval of any product or service to the exclusion of others that may be suitable.
USDA Non-Discrimination Policy
The U.S. Department of Agriculture (USDA) prohibits discrimination against its customers, employees, and applicants for employment on the bases of race, color, national origin, age, disability, sex, gender
identity, religion, reprisal, and where applicable, political beliefs, marital status, familial or parental status, sexual orientation, or all or part of an individual’s income is derived from any public assistance program,
or protected genetic information in employment or in any program or activity conducted or funded by the Department. (Not all prohibited bases will apply to all programs and/or employment activities.)
To File an Employment Complaint
If you wish to file an employment complaint, you must contact your agency’s EEO Counselor (http://www.ascr.usda.gov/doc/EEO_Counselor_List.pdf) within 45 days of the date of the alleged discriminatory
act, event, or in the case of a personnel action. Additional information can be found online at http://www.ascr.usda.gov/complaint_filing_file.html.
To File a Program Complaint
If you wish to file a Civil Rights program complaint of discrimination, complete the USDA Program Discrimination Complaint Form, found online at http://www.ascr.usda.gov/complaint_filing_cust.html, or
at any USDA office, or call (866) 632–9992 to request the form. You may also write a letter containing all of the information requested in the form. Send your completed complaint form or letter to us by mail at
U.S. Department of Agriculture, Director, Office of Adjudication, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410, by fax (202) 690–7442 or email at program.intake@usda.gov.
Persons with Disabilities
Individuals who are deaf, hard of hearing or have speech disabilities and you wish to file either an EEO or program complaint please contact USDA through the Federal Relay Service at (800) 877–8339 or
(800) 845–6136 (in Spanish). Persons with disabilities who wish to file a program complaint, please see information above on how to contact us by mail directly or by email. If you require alternative means of
communication for program information (e.g., Braille, large print, audiotape, etc.) please contact USDA’s TARGET Center at (202) 720–2600 (voice and TDD).
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