Crestwood, MO rainwater: 34,717 gallons off a roof

How much rain a roof in Crestwood, MO collects

34,717gallons a year

That is a 1,500 sq ft asphalt roof under Crestwood, MO's normal 43.7 inches of rain, about 795 gallons for every inch that falls.

In Crestwood, MO 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 St. Louis 5.7 Sw station (5.3 mi away). Crestwood, MO ranks 41st wettest of the 80 cities covered in Missouri.

Month by month in Crestwood

Month	Rain (in)	Off the roof (gal)	Garden shortfall (gal)
Jan	2.88	2,289
Feb	2.32	1,844
Mar	3.58	2,845
Apr	4.67	3,712
May	5.14	4,085
Jun	4.67	3,712
Jul	4.13	3,283	27
Aug	3.69	2,933	82
Sep	3.30	2,623	131
Oct	3.14	2,496	151
Nov	3.54	2,814
Dec	2.62	2,082

May is the wettest month (5.14 in, 4,085 gal off the roof); Feb the driest (2.32 in). Garden shortfall is what a 200 sq ft vegetable bed needs beyond the rain that lands on it, April to October.

Which tank size is worth it in Crestwood

Best fit: one 55-gallon barrel, which delivers about 322 gallons to the garden in a normal year (82.3% of its need).

Before you buy, a 55-gallon barrel with a downspout diverter is the whole job. Check that the overflow points away from your foundation, because most of Crestwood's roof water will pass straight through it.

Tank	Water used (gal/yr)	Spills over (gal/yr)
55 gal	322	33,285
110 gal	322	33,285
165 gal	322	33,285
275 gal	322	33,285
550 gal	322	33,285
1,000 gal	322	33,285
1,500 gal	322	33,285
2,500 gal	322	33,285
5,000 gal	322	33,285

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 Missouri?

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