Firestone, CO rainwater: 11,151 gallons off a roof
Firestone, CO: gallons off the roof each year
11,151gallons a year
That is a 1,500 sq ft asphalt roof under Firestone, CO's normal 14.0 inches of rain, about 795 gallons for every inch that falls.
In Firestone, 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 Longmont 8.2 Ese station (2.5 mi away). Firestone, CO ranks 47th wettest of the 53 cities covered in Colorado.
Month by month in Firestone
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 0.38 | 302 | |
| Feb | 0.47 | 374 | |
| Mar | 1.24 | 986 | |
| Apr | 1.73 | 1,375 | 327 |
| May | 2.36 | 1,876 | 248 |
| Jun | 1.36 | 1,081 | 373 |
| Jul | 1.44 | 1,145 | 363 |
| Aug | 1.23 | 978 | 389 |
| Sep | 1.61 | 1,280 | 342 |
| Oct | 1.03 | 819 | 414 |
| Nov | 0.68 | 540 | |
| Dec | 0.50 | 397 |
May is the wettest month (2.36 in, 1,876 gal off the roof); Jan the driest (0.38 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 Firestone
Best fit: 2 linked 55-gallon barrels, which delivers about 2,125 gallons to the garden in a normal year (86.6% 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 Firestone's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 1,403 | 9,208 |
| 110 gal | 2,125 | 8,486 |
| 165 gal (over cap) | 2,163 | 8,448 |
| 275 gal (over cap) | 2,163 | 8,448 |
| 550 gal (over cap) | 2,163 | 8,448 |
| 1,000 gal (over cap) | 2,163 | 8,448 |
| 1,500 gal (over cap) | 2,163 | 8,448 |
| 2,500 gal (over cap) | 2,163 | 8,448 |
| 5,000 gal (over cap) | 2,163 | 8,448 |
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