McAlester, OK rainwater: 39,311 gallons off a roof
McAlester, OK: gallons off the roof each year
39,311gallons a year
That is a 1,500 sq ft asphalt roof under McAlester, OK's normal 49.5 inches of rain, about 795 gallons for every inch that falls.
In McAlester, 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 Krebs 0.3 Wnw station (2.9 mi away). McAlester, OK ranks 2nd wettest of the 45 cities covered in Oklahoma.
Month by month in McAlester
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 2.45 | 1,947 | |
| Feb | 2.51 | 1,995 | |
| Mar | 3.77 | 2,996 | |
| Apr | 4.38 | 3,481 | |
| May | 6.39 | 5,079 | |
| Jun | 5.26 | 4,181 | |
| Jul | 4.99 | 3,966 | |
| Aug | 3.70 | 2,941 | 81 |
| Sep | 4.65 | 3,696 | |
| Oct | 4.49 | 3,569 | |
| Nov | 3.25 | 2,583 | |
| Dec | 3.62 | 2,877 |
May is the wettest month (6.39 in, 5,079 gal off the roof); Jan the driest (2.45 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 McAlester
Best fit: one 55-gallon barrel, which delivers about 71 gallons to the garden in a normal year (87.6% 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 McAlester's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 71 | 38,325 |
| 110 gal | 71 | 38,325 |
| 165 gal | 71 | 38,325 |
| 275 gal | 71 | 38,325 |
| 550 gal | 71 | 38,325 |
| 1,000 gal | 71 | 38,325 |
| 1,500 gal | 71 | 38,325 |
| 2,500 gal | 71 | 38,325 |
| 5,000 gal | 71 | 38,325 |
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