Guthrie, OK rainwater: 24,273 gallons off a roof
Rainwater from a roof in Guthrie, OK
24,273gallons a year
That is a 1,500 sq ft asphalt roof under Guthrie, OK's normal 30.5 inches of rain, about 795 gallons for every inch that falls.
In Guthrie, OK a single barrel does most of the work. Storms come often enough that a small tank refills before it runs dry, and a bigger one would mostly sit full.
Rainfall: NOAA 1991-2020 climate normals, the Guthrie Muni Ap station (1.7 mi away). Guthrie, OK ranks 40th wettest of the 45 cities covered in Oklahoma.
Month by month in Guthrie
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 1.15 | 914 | |
| Feb | 1.25 | 994 | |
| Mar | 2.03 | 1,613 | |
| Apr | 3.49 | 2,774 | 107 |
| May | 3.64 | 2,893 | 89 |
| Jun | 4.36 | 3,465 | |
| Jul | 2.73 | 2,170 | 202 |
| Aug | 2.97 | 2,361 | 172 |
| Sep | 2.72 | 2,162 | 203 |
| Oct | 2.78 | 2,210 | 196 |
| Nov | 1.94 | 1,542 | |
| Dec | 1.48 | 1,176 |
Jun is the wettest month (4.36 in, 3,465 gal off the roof); Jan the driest (1.15 in). Garden shortfall is what a 200 sq ft vegetable bed needs beyond the rain that lands on it, April to October.
Barrel or cistern in Guthrie?
Best fit: one 55-gallon barrel, which delivers about 827 gallons to the garden in a normal year (85.4% of its need).
Before you buy, a 55-gallon barrel with a downspout diverter is the whole job. Check that the overflow points away from your foundation, because most of Guthrie's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 827 | 22,697 |
| 110 gal | 827 | 22,697 |
| 165 gal | 827 | 22,697 |
| 275 gal | 827 | 22,697 |
| 550 gal | 827 | 22,697 |
| 1,000 gal | 827 | 22,697 |
| 1,500 gal | 827 | 22,697 |
| 2,500 gal | 827 | 22,697 |
| 5,000 gal | 827 | 22,697 |
Simulated storm by storm through a normal year using the station's count of days with 0.1 in or more of rain each month.
Is rainwater collection legal in Oklahoma?
Encouraged through state legislation: Water for 2060 Act
From the 2015 (Pacific Northwest National Laboratory report 24347); not yet re-checked against current law, so check with your state water agency before building anything large. Source