Rain Water Collection

Water scarcity and security is an important topic. Rain water collection barrels are a way to address water efficiency.

We can use quantitative methods to make sure that we are meeting the goals of a water collection system.

Our building has a collection system on the roof. Here are a few questions we could ask depending on our goals:

• How many barrels would we need to capture all of the rain water over a season?
• How much rain we can capture in our existing barrels before they are full and we can no longer collect rain?
• How much extra watering we can provide from the rain collection barrels to the areas in the garden that we want to irrigate.

Strategy

These and related problems are a good use of our models for volume and the technique of writing an equation.

• Equate two shapes that hold the same amount of water
• Decide which variable you are solving for in your equation
• Choose a set of units likely to make the problem easier
• Find and write down the dimensions you can measure or estimate directly
• Solve your equation
  • Use the rules of algebra
  • Use the rules of unit conversions