Marion, IN rainwater: 33,191 gallons off a roof
Marion, IN: gallons off the roof each year
33,191gallons a year
That is a 1,500 sq ft asphalt roof under Marion, IN's normal 41.8 inches of rain, about 795 gallons for every inch that falls.
In Marion, 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 Marion 2 N station (2.1 mi away). Marion, IN ranks 48th wettest of the 88 cities covered in Indiana.
Month by month in Marion
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 2.85 | 2,265 | |
| Feb | 2.15 | 1,709 | |
| Mar | 2.87 | 2,281 | |
| Apr | 4.10 | 3,259 | 31 |
| May | 4.76 | 3,783 | |
| Jun | 4.42 | 3,513 | |
| Jul | 4.33 | 3,442 | 2 |
| Aug | 3.93 | 3,124 | 52 |
| Sep | 3.39 | 2,694 | 120 |
| Oct | 3.12 | 2,480 | 153 |
| Nov | 3.26 | 2,591 | |
| Dec | 2.58 | 2,051 |
May is the wettest month (4.76 in, 3,783 gal off the roof); Feb the driest (2.15 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 Marion
Best fit: one 55-gallon barrel, which delivers about 290 gallons to the garden in a normal year (80.8% of its need).
If you set one up, a 55-gallon barrel with a downspout diverter is the whole job. Check that the overflow points away from your foundation, because most of Marion's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 290 | 31,731 |
| 110 gal | 290 | 31,731 |
| 165 gal | 290 | 31,731 |
| 275 gal | 290 | 31,731 |
| 550 gal | 290 | 31,731 |
| 1,000 gal | 290 | 31,731 |
| 1,500 gal | 290 | 31,731 |
| 2,500 gal | 290 | 31,731 |
| 5,000 gal | 290 | 31,731 |
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