Commerce City, CO rainwater: 11,215 gallons off a roof
Commerce City, CO: gallons off the roof each year
11,215gallons a year
That is a 1,500 sq ft asphalt roof under Commerce City, CO's normal 14.1 inches of rain, about 795 gallons for every inch that falls.
In Commerce City, 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 Brighton 3 Se station (4.7 mi away). Commerce City, CO ranks 46th wettest of the 53 cities covered in Colorado.
Month by month in Commerce City
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 0.42 | 334 | |
| Feb | 0.43 | 342 | |
| Mar | 0.98 | 779 | |
| Apr | 1.77 | 1,407 | 322 |
| May | 2.35 | 1,868 | 249 |
| Jun | 1.41 | 1,121 | 367 |
| Jul | 1.72 | 1,367 | 328 |
| Aug | 1.77 | 1,407 | 322 |
| Sep | 1.18 | 938 | 395 |
| Oct | 1.02 | 811 | 415 |
| Nov | 0.69 | 548 | |
| Dec | 0.37 | 294 |
May is the wettest month (2.35 in, 1,868 gal off the roof); Dec the driest (0.37 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 Commerce City
Best fit: 2 linked 55-gallon barrels, which delivers about 2,067 gallons to the garden in a normal year (86.2% 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 Commerce City's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 1,348 | 9,342 |
| 110 gal | 2,067 | 8,622 |
| 165 gal (over cap) | 2,123 | 8,567 |
| 275 gal (over cap) | 2,123 | 8,567 |
| 550 gal (over cap) | 2,123 | 8,567 |
| 1,000 gal (over cap) | 2,123 | 8,567 |
| 1,500 gal (over cap) | 2,123 | 8,567 |
| 2,500 gal (over cap) | 2,123 | 8,567 |
| 5,000 gal (over cap) | 2,123 | 8,567 |
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