Ithaca, NY rainwater: 30,433 gallons off a roof
How much rain a roof in Ithaca, NY collects
30,433gallons a year
That is a 1,500 sq ft asphalt roof under Ithaca, NY's normal 38.3 inches of rain, about 795 gallons for every inch that falls.
In Ithaca, NY 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 Ithaca Cornell Univ station (2.8 mi away). Ithaca, NY ranks 81st wettest of the 90 cities covered in New York.
Month by month in Ithaca
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 2.24 | 1,780 | |
| Feb | 1.98 | 1,574 | |
| Mar | 2.78 | 2,210 | |
| Apr | 3.40 | 2,702 | 118 |
| May | 3.20 | 2,543 | 143 |
| Jun | 3.98 | 3,163 | 46 |
| Jul | 3.90 | 3,100 | 56 |
| Aug | 3.77 | 2,996 | 72 |
| Sep | 3.83 | 3,044 | 65 |
| Oct | 3.70 | 2,941 | 81 |
| Nov | 2.94 | 2,337 | |
| Dec | 2.57 | 2,043 |
Jun is the wettest month (3.98 in, 3,163 gal off the roof); Feb the driest (1.98 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 Ithaca
Best fit: one 55-gallon barrel, which delivers about 435 gallons to the garden in a normal year (74.7% 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 Ithaca's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 435 | 28,739 |
| 110 gal | 435 | 28,739 |
| 165 gal | 435 | 28,739 |
| 275 gal | 435 | 28,739 |
| 550 gal | 435 | 28,739 |
| 1,000 gal | 435 | 28,739 |
| 1,500 gal | 435 | 28,739 |
| 2,500 gal | 435 | 28,739 |
| 5,000 gal | 435 | 28,739 |
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 New York?
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