Windsor, CO rainwater: 12,598 gallons off a roof
How much rain a roof in Windsor, CO collects
12,598gallons a year
That is a 1,500 sq ft asphalt roof under Windsor, CO's normal 15.9 inches of rain, about 795 gallons for every inch that falls.
In Windsor, 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 Fort Collins 9.6 Se station (2.8 mi away). Windsor, CO ranks 32nd wettest of the 53 cities covered in Colorado.
Month by month in Windsor
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 0.41 | 326 | |
| Feb | 0.47 | 374 | |
| Mar | 1.15 | 914 | |
| Apr | 1.92 | 1,526 | 303 |
| May | 2.98 | 2,369 | 171 |
| Jun | 1.81 | 1,439 | 317 |
| Jul | 1.71 | 1,359 | 329 |
| Aug | 1.56 | 1,240 | 348 |
| Sep | 1.45 | 1,152 | 362 |
| Oct | 1.23 | 978 | 389 |
| Nov | 0.67 | 533 | |
| Dec | 0.49 | 389 |
May is the wettest month (2.98 in, 2,369 gal off the roof); Jan the driest (0.41 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 Windsor?
Best fit: 2 linked 55-gallon barrels, which delivers about 1,858 gallons to the garden in a normal year (83.8% of its need).
Before you buy, a 55-gallon barrel with a downspout diverter is the whole job. Check that the overflow points away from your foundation, because most of Windsor's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 1,307 | 10,721 |
| 110 gal | 1,858 | 10,170 |
| 165 gal (over cap) | 1,942 | 10,085 |
| 275 gal (over cap) | 1,946 | 10,082 |
| 550 gal (over cap) | 1,946 | 10,082 |
| 1,000 gal (over cap) | 1,946 | 10,082 |
| 1,500 gal (over cap) | 1,946 | 10,082 |
| 2,500 gal (over cap) | 1,946 | 10,082 |
| 5,000 gal (over cap) | 1,946 | 10,082 |
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