Laramie, WY rainwater: 11,556 gallons off a roof

Laramie, WY: gallons off the roof each year

11,556gallons a year

That is a 1,500 sq ft asphalt roof under Laramie, WY's normal 14.5 inches of rain, about 795 gallons for every inch that falls.

In Laramie, WY 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 Laramie .73 Ene station (1.5 mi away). Laramie, WY ranks 5th wettest of the 11 cities covered in Wyoming.

Month by month in Laramie

Month	Rain (in)	Off the roof (gal)	Garden shortfall (gal)
Jan	0.55	437
Feb	0.59	469
Mar	0.99	787
Apr	1.70	1,351	330
May	1.92	1,526	303
Jun	1.74	1,383	325
Jul	1.78	1,415	320
Aug	1.30	1,033	380
Sep	1.46	1,160	360
Oct	1.25	994	386
Nov	0.81	644
Dec	0.45	358

May is the wettest month (1.92 in, 1,526 gal off the roof); Dec the driest (0.45 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 Laramie

Best fit: 2 linked 55-gallon barrels, which delivers about 2,016 gallons to the garden in a normal year (83.8% 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 Laramie's roof water will pass straight through it.

Tank	Water used (gal/yr)	Spills over (gal/yr)
55 gal	1,383	9,708
110 gal	2,016	9,075
165 gal	2,109	8,983
275 gal	2,131	8,961
550 gal	2,131	8,961
1,000 gal	2,131	8,961
1,500 gal	2,131	8,961
2,500 gal	2,131	8,961
5,000 gal	2,131	8,961

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 Wyoming?

No rainwater harvesting regulations

From the 2015 (Pacific Northwest National Laboratory report 24347); not yet re-checked against current law, so check with your state water agency before building anything large. Source