RoofRainYield

Morton, IL rainwater: 31,228 gallons off a roof

Rainwater from a roof in Morton, IL

31,228gallons a year

That is a 1,500 sq ft asphalt roof under Morton, IL's normal 39.3 inches of rain, about 795 gallons for every inch that falls.

In Morton, IL 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 Morton station (0.9 mi away). Morton, IL ranks 149th wettest of the 225 cities covered in Illinois.

Month by month in Morton

MonthRain (in)Off the roof (gal)Garden shortfall (gal)
Jan2.211,757
Feb2.001,590
Mar2.762,194
Apr3.963,14749
May5.044,006
Jun4.003,17944
Jul4.103,25931
Aug3.522,798103
Sep3.272,599135
Oct3.212,551142
Nov2.942,337
Dec2.281,812

May is the wettest month (5.04 in, 4,006 gal off the roof); Feb the driest (2.00 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 Morton?

Best fit: one 55-gallon barrel, which delivers about 400 gallons to the garden in a normal year (79.4% 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 Morton's roof water will pass straight through it.

TankWater used (gal/yr)Spills over (gal/yr)
55 gal40029,718
110 gal40029,718
165 gal40029,718
275 gal40029,718
550 gal40029,718
1,000 gal40029,718
1,500 gal40029,718
2,500 gal40029,718
5,000 gal40029,718

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 Illinois?

Local government can regulate rainwater harvesting per state plumbing law

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