| A | B | C | D | E | F | G | |
| 1 | Water Consumption | 1,134 | Key | ||||
| 2 | Roof Length | 36 | Yellow values are given | ||||
| 3 | Roof Width | 31 | Blue values are calculated | ||||
| 4 | Usable Cistern Height | 7 | Red values can be manipulated. | ||||
| 5 | Usable Cistern Width | 9 | Green Values are totals. | ||||
| 6 | Usable Cistern Length | 11 | |||||
| 7 | Gallons of Water Purchased | 3,000 | |||||
| 8 | |||||||
| 9 | |||||||
| 10 | Cistern Gallon Volume | 5,184 | |||||
| 11 | Roof Generates X Gallons per Inch | 696 | |||||
| 12 | Cistern Vol = 5,184 | ||||||
| 13 | Month | Rainfall | Gallons Rain | Water Used | Gallons Bought | Waste | Cistern Volume |
| 14 | Jan-90 | 0.6348 | 442 | 1,134 | - | - | 2,308 |
| 15 | Feb-90 | 1.1348 | 789 | 1,134 | - | - | 1,963 |
| 16 | Mar-90 | 2.1348 | 1,485 | 1,134 | - | - | 2,314 |
| 17 | Apr-90 | 1.6348 | 1,137 | 1,134 | - | - | 2,317 |
| 18 | May-90 | 0.6348 | 442 | 1,134 | - | - | 1,625 |
| 19 | Jun-90 | 0.6348 | 442 | 1,134 | - | - | 932 |
| 20 | Jul-90 | 0.6348 | 442 | 1,134 | - | - | 240 |
| 21 | Aug-90 | 1.1348 | 789 | 1,134 | - | - | (105) |
| 22 | Sep-90 | 1.1348 | 789 | 1,134 | 3,000 | - | 2,551 |
| 23 | Oct-90 | 3.1348 | 2,181 | 1,134 | - | - | 3,598 |
| 24 | Nov-90 | 1.1348 | 789 | 1,134 | - | - | 3,253 |
| 25 | Dec-90 | 0.6348 | 442 | 1,134 | - | - | 2,561 |
| 26 | Jan-91 | 0.5348 | 372 | 1,134 | - | - | 1,799 |
| 27 | Feb-91 | 0.9348 | 650 | 1,134 | - | - | 1,315 |
| 28 | Mar-91 | 1.7348 | 1,207 | 1,134 | - | - | 1,388 |
| 29 | Apr-91 | 1.3348 | 929 | 1,134 | - | - | 1,182 |
| 30 | May-91 | 0.5348 | 372 | 1,134 | - | - | 420 |
| 31 | Jun-91 | 0.5348 | 372 | 1,134 | - | - | (342) |
| 32 | Jul-91 | 0.5348 | 372 | 1,134 | 3,000 | - | 1,896 |
| 33 | Aug-91 | 0.9348 | 650 | 1,134 | - | - | 1,413 |
| 34 | Sep-91 | 0.9348 | 650 | 1,134 | - | - | 929 |
| 35 | Oct-91 | 2.5348 | 1,763 | 1,134 | - | - | 1,558 |
| 36 | Nov-91 | 0.9348 | 650 | 1,134 | - | - | 1,074 |
| 37 | Dec-91 | 0.5348 | 372 | 1,134 | - | - | 313 |
| 38 | Jan-92 | 0.6848 | 476 | 1,134 | - | - | (345) |
| 39 | Feb-92 | 1.2348 | 859 | 1,134 | 3,000 | - | 2,380 |
| 40 | Mar-92 | 2.3348 | 1,624 | 1,134 | - | - | 2,870 |
| 41 | Apr-92 | 1.7848 | 1,242 | 1,134 | - | - | 2,978 |
| 42 | May-92 | 0.6848 | 476 | 1,134 | - | - | 2,320 |
| 43 | Jun-92 | 0.6848 | 476 | 1,134 | - | - | 1,662 |
| 44 | Jul-92 | 0.6848 | 476 | 1,134 | - | - | 1,005 |
| 45 | Aug-92 | 1.2348 | 859 | 1,134 | - | - | 730 |
| 46 | Sep-92 | 1.2348 | 859 | 1,134 | - | - | 455 |
| 47 | Oct-92 | 3.4348 | 2,389 | 1,134 | - | - | 1,710 |
| 48 | Nov-92 | 1.2348 | 859 | 1,134 | - | - | 1,435 |
| 49 | Dec-92 | 0.6848 | 476 | 1,134 | - | - | 777 |
| 50 | Jan-93 | 0.6098 | 424 | 1,134 | - | - | 68 |
| 51 | Feb-93 | 1.0848 | 755 | 1,134 | - | - | (312) |
| 52 | Mar-93 | 2.0348 | 1,415 | 1,134 | 3,000 | - | 2,970 |
| 53 | Apr-93 | 1.5598 | 1,085 | 1,134 | - | - | 2,921 |
| 54 | May-93 | 0.6098 | 424 | 1,134 | - | - | 2,211 |
| 55 | Jun-93 | 0.6098 | 424 | 1,134 | - | - | 1,501 |
| 56 | Jul-93 | 0.6098 | 424 | 1,134 | - | - | 791 |
| 57 | Aug-93 | 1.0848 | 755 | 1,134 | - | - | 412 |
| 58 | Sep-93 | 1.0848 | 755 | 1,134 | - | - | 33 |
| 59 | Oct-93 | 2.9848 | 2,076 | 1,134 | - | - | 975 |
| 60 | Nov-93 | 1.0848 | 755 | 1,134 | - | - | 596 |
| 61 | Dec-93 | 0.6098 | 424 | 1,134 | - | - | (114) |
| 62 | Jan-94 | 0.5848 | 407 | 1,134 | 3,000 | - | 2,159 |
| 63 | Feb-94 | 1.0348 | 720 | 1,134 | - | - | 1,745 |
| 64 | Mar-94 | 1.9348 | 1,346 | 1,134 | - | - | 1,956 |
| 65 | Apr-94 | 1.4848 | 1,033 | 1,134 | - | - | 1,855 |
| 66 | May-94 | 0.5848 | 407 | 1,134 | - | - | 1,128 |
| 67 | Jun-94 | 0.5848 | 407 | 1,134 | - | - | 401 |
| 68 | Jul-94 | 0.5848 | 407 | 1,134 | - | - | (326) |
| 69 | Aug-94 | 1.0348 | 720 | 1,134 | 3,000 | - | 2,260 |
| 70 | Sep-94 | 1.0348 | 720 | 1,134 | - | - | 1,845 |
| 71 | Oct-94 | 2.8348 | 1,972 | 1,134 | - | - | 2,683 |
| 72 | Nov-94 | 1.0348 | 720 | 1,134 | - | - | 2,269 |
| 73 | Dec-94 | 0.5848 | 407 | 1,134 | - | - | 1,542 |
| 74 | Jan-95 | 0.5598 | 389 | 1,134 | - | - | 798 |
| 75 | Feb-95 | 0.9848 | 685 | 1,134 | - | - | 349 |
| 76 | Mar-95 | 1.8348 | 1,276 | 1,134 | - | - | 491 |
| 77 | Apr-95 | 1.4098 | 981 | 1,134 | - | - | 338 |
| 78 | May-95 | 0.5598 | 389 | 1,134 | - | - | (407) |
| 79 | Jun-95 | 0.5598 | 389 | 1,134 | 3,000 | - | 1,849 |
| 80 | Jul-95 | 0.5598 | 389 | 1,134 | - | - | 1,104 |
| 81 | Aug-95 | 0.9848 | 685 | 1,134 | - | - | 655 |
| 82 | Sep-95 | 0.9848 | 685 | 1,134 | - | - | 206 |
| 83 | Oct-95 | 2.6848 | 1,868 | 1,134 | - | - | 940 |
| 84 | Nov-95 | 0.9848 | 685 | 1,134 | - | - | 491 |
| 85 | Dec-95 | 0.5598 | 389 | 1,134 | - | - | (254) |
This table was created by a free Excel macro written by Charles Balch.
Here's the code. It is care ware - it's yours for free if do something nice for anyone (anyone includes you).