Erie, CO rainwater: 12,852 gallons off a roof
Rainwater from a roof in Erie, CO
12,852gallons a year
That is a 1,500 sq ft asphalt roof under Erie, CO's normal 16.2 inches of rain, about 795 gallons for every inch that falls.
In Erie, 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 Erie 1.5 Nne station (0.6 mi away). Erie, CO ranks 29th wettest of the 53 cities covered in Colorado.
Month by month in Erie
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 0.57 | 453 | |
| Feb | 0.61 | 485 | |
| Mar | 1.57 | 1,248 | |
| Apr | 1.89 | 1,502 | 307 |
| May | 2.60 | 2,066 | 218 |
| Jun | 1.58 | 1,256 | 345 |
| Jul | 1.80 | 1,431 | 318 |
| Aug | 1.44 | 1,145 | 363 |
| Sep | 1.60 | 1,272 | 343 |
| Oct | 1.21 | 962 | 391 |
| Nov | 0.77 | 612 | |
| Dec | 0.53 | 421 |
May is the wettest month (2.60 in, 2,066 gal off the roof); Dec the driest (0.53 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 Erie
Best fit: 2 linked 55-gallon barrels, which delivers about 2,003 gallons to the garden in a normal year (87.6% 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 Erie's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 1,352 | 10,945 |
| 110 gal | 2,003 | 10,294 |
| 165 gal (over cap) | 2,016 | 10,281 |
| 275 gal (over cap) | 2,016 | 10,281 |
| 550 gal (over cap) | 2,016 | 10,281 |
| 1,000 gal (over cap) | 2,016 | 10,281 |
| 1,500 gal (over cap) | 2,016 | 10,281 |
| 2,500 gal (over cap) | 2,016 | 10,281 |
| 5,000 gal (over cap) | 2,016 | 10,281 |
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