Bethany, OK rainwater: 29,098 gallons off a roof
Bethany, OK: gallons off the roof each year
29,098gallons a year
That is a 1,500 sq ft asphalt roof under Bethany, OK's normal 36.6 inches of rain, about 795 gallons for every inch that falls.
In Bethany, 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 Warr Acres 0.4 Sse station (1.8 mi away). Bethany, OK ranks 28th wettest of the 45 cities covered in Oklahoma.
Month by month in Bethany
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 1.18 | 938 | |
| Feb | 1.42 | 1,129 | |
| Mar | 2.41 | 1,915 | |
| Apr | 3.62 | 2,877 | 91 |
| May | 5.17 | 4,109 | |
| Jun | 4.94 | 3,926 | |
| Jul | 3.56 | 2,830 | 98 |
| Aug | 3.47 | 2,758 | 110 |
| Sep | 3.75 | 2,981 | 75 |
| Oct | 3.44 | 2,734 | 113 |
| Nov | 1.81 | 1,439 | |
| Dec | 1.84 | 1,462 |
May is the wettest month (5.17 in, 4,109 gal off the roof); Jan the driest (1.18 in). Garden shortfall is what a 200 sq ft vegetable bed needs beyond the rain that lands on it, April to October.
What size rain barrel for Bethany
Best fit: one 55-gallon barrel, which delivers about 420 gallons to the garden in a normal year (86.2% 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 Bethany's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 420 | 28,017 |
| 110 gal | 420 | 28,017 |
| 165 gal | 420 | 28,017 |
| 275 gal | 420 | 28,017 |
| 550 gal | 420 | 28,017 |
| 1,000 gal | 420 | 28,017 |
| 1,500 gal | 420 | 28,017 |
| 2,500 gal | 420 | 28,017 |
| 5,000 gal | 420 | 28,017 |
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