Greeley, CO rainwater: 11,469 gallons off a roof
How much rain a roof in Greeley, CO collects
11,469gallons a year
That is a 1,500 sq ft asphalt roof under Greeley, CO's normal 14.4 inches of rain, about 795 gallons for every inch that falls.
In Greeley, CO 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 Greeley 4.4 W station (1.1 mi away). Greeley, CO ranks 41st wettest of the 53 cities covered in Colorado.
Month by month in Greeley
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 0.30 | 238 | |
| Feb | 0.35 | 278 | |
| Mar | 0.80 | 636 | |
| Apr | 1.50 | 1,192 | 355 |
| May | 2.94 | 2,337 | 176 |
| Jun | 2.06 | 1,637 | 286 |
| Jul | 1.51 | 1,200 | 354 |
| Aug | 1.62 | 1,288 | 340 |
| Sep | 1.33 | 1,057 | 377 |
| Oct | 1.07 | 850 | 409 |
| Nov | 0.52 | 413 | |
| Dec | 0.43 | 342 |
May is the wettest month (2.94 in, 2,337 gal off the roof); Jan the driest (0.30 in). Garden shortfall is what a 200 sq ft vegetable bed needs beyond the rain that lands on it, April to October.
Barrel or cistern in Greeley?
Best fit: 2 linked 55-gallon barrels, which delivers about 1,994 gallons to the garden in a normal year (86.8% 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 Greeley's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 1,301 | 9,658 |
| 110 gal | 1,994 | 8,965 |
| 165 gal (over cap) | 2,031 | 8,928 |
| 275 gal (over cap) | 2,031 | 8,928 |
| 550 gal (over cap) | 2,031 | 8,928 |
| 1,000 gal (over cap) | 2,031 | 8,928 |
| 1,500 gal (over cap) | 2,031 | 8,928 |
| 2,500 gal (over cap) | 2,031 | 8,928 |
| 5,000 gal (over cap) | 2,031 | 8,928 |
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 Colorado?
Most households may use rain barrels: a maximum of two rain barrels with a combined storage of 110 gallons or less per household, rooftop runoff only, used outdoors on the same property (HB16-1005). Larger rooftop collection only for qualifying well-permit holders (SB09-080) or pilot projects (HB09-1129).
Checked against the current source on 2026-11-06. Source