# Swale Holding Capacity

To determine how much water a swale can hold, first find its volume in cubic feet. Total cubic feet is then multiplied by 7.48 (the number of gallons in a cubic foot), to determine how many gallons of water the swale can retain.

Because the shape of a swale is basically half an *oval cylinder* we plug its dimensions into the formula for the volume of an oval cylinder and take half of that number (divide by two). *Note: if the width and depth of the swale are the same, use the formula for volume of a regular cylinder).

**The formula for volume of an oval cylinder is:**

Pi ** x** *length*/2 **x** *width*/2 **x** *height*

Where:

***length**= Swale’s Width, **w****idth** = Swale’s Depth **x** 2, and **height**** **= Swale’s Length

Next, because the swale is actually only half of an oval cylinder, you would** divide by 2;** your answer is in cubic feet.

**Multiply your answer by 7.48** (the number of gallons held by 1 cubic ft). This will give you the total gallons of water your swale can hold.

Click here for a specific step by step example.

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