Watertown, NY rainwater: 35,258 gallons off a roof
Rainwater from a roof in Watertown, NY
35,258gallons a year
That is a 1,500 sq ft asphalt roof under Watertown, NY's normal 44.4 inches of rain, about 795 gallons for every inch that falls.
In Watertown, 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 Watertown station (1.7 mi away). Watertown, NY ranks 58th wettest of the 90 cities covered in New York.
Month by month in Watertown
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 3.58 | 2,845 | |
| Feb | 2.88 | 2,289 | |
| Mar | 2.75 | 2,186 | |
| Apr | 3.53 | 2,806 | 102 |
| May | 3.65 | 2,901 | 87 |
| Jun | 3.71 | 2,949 | 80 |
| Jul | 3.47 | 2,758 | 110 |
| Aug | 3.84 | 3,052 | 64 |
| Sep | 3.85 | 3,060 | 62 |
| Oct | 5.01 | 3,982 | |
| Nov | 4.24 | 3,370 | |
| Dec | 3.85 | 3,060 |
Oct is the wettest month (5.01 in, 3,982 gal off the roof); Mar the driest (2.75 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 Watertown
Best fit: one 55-gallon barrel, which delivers about 378 gallons to the garden in a normal year (74.9% 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 Watertown's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 378 | 33,364 |
| 110 gal | 378 | 33,364 |
| 165 gal | 378 | 33,364 |
| 275 gal | 378 | 33,364 |
| 550 gal | 378 | 33,364 |
| 1,000 gal | 378 | 33,364 |
| 1,500 gal | 378 | 33,364 |
| 2,500 gal | 378 | 33,364 |
| 5,000 gal | 378 | 33,364 |
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