Hays, KS rainwater: 19,751 gallons off a roof

Hays, KS: gallons off the roof each year

19,751gallons a year

That is a 1,500 sq ft asphalt roof under Hays, KS's normal 24.8 inches of rain, about 795 gallons for every inch that falls.

In Hays, KS 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 Hays 0.3 Wsw station (0.4 mi away). Hays, KS ranks 35th wettest of the 38 cities covered in Kansas.

Month by month in Hays

Month	Rain (in)	Off the roof (gal)	Garden shortfall (gal)
Jan	0.60	477
Feb	0.79	628
Mar	1.41	1,121
Apr	2.12	1,685	278
May	3.89	3,092	57
Jun	3.18	2,527	146
Jul	3.77	2,996	72
Aug	3.42	2,718	116
Sep	2.13	1,693	277
Oct	1.81	1,439	317
Nov	0.97	771
Dec	0.76	604

May is the wettest month (3.89 in, 3,092 gal off the roof); Jan the driest (0.60 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 Hays

Best fit: one 55-gallon barrel, which delivers about 997 gallons to the garden in a normal year (78.9% 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 Hays's roof water will pass straight through it.

Tank	Water used (gal/yr)	Spills over (gal/yr)
55 gal	997	18,064
110 gal	1,069	17,992
165 gal	1,069	17,992
275 gal	1,069	17,992
550 gal	1,069	17,992
1,000 gal	1,069	17,992
1,500 gal	1,069	17,992
2,500 gal	1,069	17,992
5,000 gal	1,069	17,992

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 Kansas?

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