Decatur, IN rainwater: 32,285 gallons off a roof
How much rain a roof in Decatur, IN collects
32,285gallons a year
That is a 1,500 sq ft asphalt roof under Decatur, IN's normal 40.6 inches of rain, about 795 gallons for every inch that falls.
In Decatur, IN 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 Decatur 1 N station (1.3 mi away). Decatur, IN ranks 67th wettest of the 88 cities covered in Indiana.
Month by month in Decatur
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 2.51 | 1,995 | |
| Feb | 2.07 | 1,645 | |
| Mar | 2.75 | 2,186 | |
| Apr | 4.08 | 3,243 | 34 |
| May | 4.75 | 3,775 | |
| Jun | 4.58 | 3,640 | |
| Jul | 4.26 | 3,386 | 11 |
| Aug | 4.04 | 3,211 | 39 |
| Sep | 3.04 | 2,416 | 163 |
| Oct | 2.91 | 2,313 | 180 |
| Nov | 3.04 | 2,416 | |
| Dec | 2.59 | 2,059 |
May is the wettest month (4.75 in, 3,775 gal off the roof); Feb the driest (2.07 in). Garden shortfall is what a 200 sq ft vegetable bed needs beyond the rain that lands on it, April to October.
Which tank size is worth it in Decatur
Best fit: one 55-gallon barrel, which delivers about 346 gallons to the garden in a normal year (81.1% 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 Decatur's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 346 | 30,784 |
| 110 gal | 346 | 30,784 |
| 165 gal | 346 | 30,784 |
| 275 gal | 346 | 30,784 |
| 550 gal | 346 | 30,784 |
| 1,000 gal | 346 | 30,784 |
| 1,500 gal | 346 | 30,784 |
| 2,500 gal | 346 | 30,784 |
| 5,000 gal | 346 | 30,784 |
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 Indiana?
No statewide rainwater harvesting regulations; check county for local incentives
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