Riverton, WY rainwater: 7,551 gallons off a roof

How much rain a roof in Riverton, WY collects

7,551gallons a year

That is a 1,500 sq ft asphalt roof under Riverton, WY's normal 9.5 inches of rain, about 795 gallons for every inch that falls.

Riverton, WY has gaps between storms long enough to drain a single barrel. Around 275 gallons of storage catches most of what is worth catching.

Rainfall: NOAA 1991-2020 climate normals, the Riverton station (0.5 mi away). Riverton, WY ranks 11th wettest of the 11 cities covered in Wyoming.

Month by month in Riverton

Month	Rain (in)	Off the roof (gal)	Garden shortfall (gal)
Jan	0.35	278
Feb	0.43	342
Mar	0.71	564
Apr	1.31	1,041	379
May	1.98	1,574	295
Jun	1.09	866	406
Jul	0.70	556	455
Aug	0.45	358	486
Sep	0.80	636	443
Oct	0.93	739	426
Nov	0.44	350
Dec	0.31	246

May is the wettest month (1.98 in, 1,574 gal off the roof); Dec the driest (0.31 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 Riverton?

Best fit: a 275-gallon tote or tank, which delivers about 2,576 gallons to the garden in a normal year (89.1% of its need).

Before you buy, link barrels with a short hose at the base so they fill and drain together, and check the overflow points away from the house.

Tank	Water used (gal/yr)	Spills over (gal/yr)
55 gal	1,109	6,037
110 gal	1,840	5,305
165 gal	2,294	4,852
275 gal	2,576	4,569
550 gal	2,635	4,511
1,000 gal	2,635	4,511
1,500 gal	2,635	4,511
2,500 gal	2,635	4,511
5,000 gal	2,635	4,022

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