Oh, boy.
The normal rain fall for the rainiest month (August) in Tampa is 7.6".
http://www.rssweather.com/climate/Florida/Tampa/
7.6" / 31 Days = less than .25" per day for the rainiest month of the
year in which it rains almost every day around 4:00 to 5:00Pm due to
convection.
@ .25" of rain fall, collecting 1000 gallons normal day would require
a single-story house footprint of 8,400ft2.
Good message, shaky messenger.
For anyone interested in this idea, get your average rain/snow fall
and plug them into this spread-sheet:
Curbie
Value Unit Note Expression
Location Rain & Snow Falls 1
Average (AVErain) 0.25 Inches 2
Average (AVEsnow) 0.00 Inches 3
Factor of Normalization (Fnorm) 80% 4
Factor of Concentration of Rain (FconR) 75% 5
Normal (NORrain) 0.20 Inches 6 =AVErain * Fnorm
Normal (NORsnow) 0.00 Inches 7 =AVEsnow * Fnorm
Roof Catchment 8
Length (RCl) 200 Feet 9
Width (RCw) 45 Feet 9
Roof Capture of Rain (FRCrain) 90% 10
Roof Capture of Snow (FRCsnow) 10% 11
Area (RCa) 9000 Feet^2 12 =RCl * RCw
Roof Catchment of Rain (RCrain) 1010 Gallons 13 =NORrain *
(CuFt2Gal / In2Ft) * RCa * FRCrain
Roof Catchment of Snow (RCsnow) 0 Gallons 14 =NORsnow *
(CuFt2Gal / In2Ft) * RCa * FRCsnow * Fsnowpack
Roof Catchment of Both (RCboth) 1010 Gallons 15 =RCrain +
Rcsnow
Ground Catchment 16
Diameter (GCd) 35 Feet 17
Factor of Ground Catchment (FGC) 60% 18
Factor of Snow Pack (Fsnowpack) 30% 19
Area (GCa) 962 Feet^2 20 =PI() * (GCd / 2)^2
Ground Catchment of Snow (GCsnow) 0 Gallons 21
=NORsnow * (CuFt2Gal / In2Ft) * GCa * FGC * Fsnowpack
Ground Catchment of Rain (GCrain) 72 Gallons 22
=NORrain * (CuFt2Gal / In2Ft) * GCa * FGC
Ground Catchment of Both (GCboth) 72 Gallons 23
=GCsnow + GCrain
Cistern 24
Height (Hcist) 7 Feet 25
Roof Cistern Volume (RCVcist) 101 Feet^3 26 =(RCboth /
CuFt2Gal) * FconR
Roof Cistern Diameter (RCDcist) 4.3 Feet 27 =SQRT(RCVcist
/ Hcist / PI()) * 2
Ground Cistern Volume (GCVcist) 10 Feet^3 28 =GCboth /
CuFt2Gal
Ground Cistern Diameter (GCDcist) 1 Feet 29
=SQRT(GCVcist / Hcist / PI()) * 2
Combined Volume (CVcist) 111 Feet^3 30 =RCVcist +
GCVcist
Combined Diameter (CDcist) 4 Feet 31 =SQRT(CVcist /
Hcist / PI()) * 2
Total Harvest of Both (Harvest) 1082 Gallons 32 =RCboth +
Scboth
1 Cubic Foot of Water (CuFt2Gal) 7.481 Gallons 33
Inches to Foot (In2Ft) 12 Inches 34
Footnotes
[01] Care must be taken with the term "precipitation" which is any
form of water falling to the earth (rain, snow, hail, sleet, or mist).
I separate rain
& snow because snow accumulates all season, but is collected
as water all at once in the spring melt, where as rain collects as it
falls
during a location's rain season.
[02] Average rain fall includes the odd wet and dry years which may
lead to improperly sized system.
[03] Average snow fall includes the odd wet and dry years which may
lead to improperly sized system.
[04] Adjusts the percentage of average yearly rain and snow fall to
excludes the odd wet and dry year which may lead to improperly sized
system.
[05] Adjusts the percentage of rain season "concentration", short rain
seasons concentrate the yearly rain into a short period of time, where
long
rain seasons distribute the rain over the entire season. This
can be a major consideration in sizing a cistern, selecting a higher
concentration
percentage (short rain season) will increase cisterns storage
capacity, a lower concentration percent will decease storage capacity.
This
factor only effects rain, snow falls all snow season and
accumulates as standing snow, but melts all at once into the cistern.
[06] Normal rain fall is what "normally" falls in an area excluding
the odd wet or dry year, and can be adjusted by the "normalization"
factor.
[07] Normal snow fall is what "normally" falls in an area excluding
the odd wet or dry year, and can be adjusted by the "normalization"
factor.
[08] Building roof structures are generally square, thus so are roof
catchment areas.
[09] This are the total "length" and "width" of the roof catchment
area, if you're using the areas of more than one structure, calculate
each
structure separately, then add these individual areas together
for a total area. Lastly choose any "length" and "width" values that
equal the
combined total area.
[10] Adjusts the percentage of rain fall that is "captured" by a roof,
some bounces away and some is forced off the gable side of the roof.
[11] Adjusts the percentage of snow fall that is "captured" by a roof,
most snow slides off roofs in sheets during it's accumulation period.
[12] This is the total roof catchment area.
[13] This is the total harvest of rain fall by the roof catchment area
in gallons.
[14] This is the total harvest of snow fall by the roof catchment area
in gallons.
[15] This is the total harvest of both rain and snow fall by the roof
catchment area in gallons.
[16] Again care must be taken with the term "precipitation". Catchment
takes place on the ground, generally in a buried cistern.
rain fall which takes place on a structure where snow can slide
off roofs in sheets.
[17] Ground catchment area is better measured by the diameter around a
buried cistern. This is the diameter where rain falls or snow falls or
is
piled-up.
[18] Adjusts the percentage of rain or snow fall that is "captured",
some will seep into the ground around the cistern without being
captured.
[19] Adjusts the percentage of snow fall "pack", from 10% for powder
up to 40% for piled-up or packed snow is typical.
[20] The total catchment area in feet^2 for the diameter of a ground
buried cistern given.
[21] This is the total harvest of snow fall by the ground catchment
area in gallons.
[22] This is the total harvest of rain fall by the ground catchment
area in gallons.
[23] This is the total harvest of both rain and snow fall by the
ground catchment area in gallons.
[24] For structural reasons, cisterns should be round, rain and snow
cisterns may be separate or combines, a rain cistern may be by your
house
and a snow cistern may out close to a garden or livestock. It
all depends on someone's needs and resources.
[25] The height is used for BOTH rain and snow cisterns,
considerations given to frost line depth (water freezes), soil type
and pack, and water
table depth will help determine height for buried cisterns.
[26] Roof cistern volume in cubic feet as determined by the water
harvested by the specified roof catchment.
[27] Roof cistern diameter needed to store the volume of water
harvested from the roof catchment.
[28] Ground cistern volume in cubic feet as determined by the water
harvested by the specified ground catchment.
[29] Ground cistern diameter needed to store the volume of water
harvested from the ground catchment.
[30] Combined rain & snow cistern volume in cubic feet as determined
by the harvest of both catchments.
[31] Combined rain & snow cistern diameter in feet as determined by
the harvest of both catchments.
[32] Combined rain & snow cistern volume in gallons as determined by
the harvest of both catchments.
[33] Constant for gallons of water in a single cubic foot.
[34] Constant for inches in a foot.