Evansville, IN rainwater: 37,984 gallons off a roof
Evansville, IN: gallons off the roof each year
37,984gallons a year
That is a 1,500 sq ft asphalt roof under Evansville, IN's normal 47.8 inches of rain, about 795 gallons for every inch that falls.
In Evansville, 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 Evansville Museum station (2.6 mi away). Evansville, IN ranks 10th wettest of the 88 cities covered in Indiana.
Month by month in Evansville
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 3.48 | 2,766 | |
| Feb | 3.35 | 2,663 | |
| Mar | 4.69 | 3,728 | |
| Apr | 5.22 | 4,149 | |
| May | 4.78 | 3,799 | |
| Jun | 4.37 | 3,473 | |
| Jul | 4.48 | 3,561 | |
| Aug | 3.10 | 2,464 | 156 |
| Sep | 3.40 | 2,702 | 118 |
| Oct | 3.32 | 2,639 | 128 |
| Nov | 3.97 | 3,155 | |
| Dec | 3.63 | 2,885 |
Apr is the wettest month (5.22 in, 4,149 gal off the roof); Aug the driest (3.10 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 Evansville
Best fit: one 55-gallon barrel, which delivers about 338 gallons to the garden in a normal year (83.9% of its need).
If you buy one, a 55-gallon barrel with a downspout diverter is the whole job. Check that the overflow points away from your foundation, because most of Evansville's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 338 | 36,536 |
| 110 gal | 338 | 36,536 |
| 165 gal | 338 | 36,536 |
| 275 gal | 338 | 36,536 |
| 550 gal | 338 | 36,536 |
| 1,000 gal | 338 | 36,536 |
| 1,500 gal | 338 | 36,536 |
| 2,500 gal | 338 | 36,536 |
| 5,000 gal | 338 | 36,536 |
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