When designing your Pond Free water feature, it is important that your basin holds enough water to support the system and that it is properly lined. Make sure the kit you choose has an adequate liner size for the waterfall and basin. You will start by figuring how much water you have in transit.

Calculating Water in Transit (Streamway Length)

Water in transit is the total volume of water that is moving in your system. This is used for figuring the size the basin needs to be. Use the equation below to calculate the amount of water in your feature.

L x W x 0.25 x 7.48= Water in transit (WIT)

L represents the length of the waterfall and streamway
W is the width of the waterfall and streamway
0.25 is the depth of the streamway in ft.
7.48 is the number of gallons that 1 cubic foot can hold

This average does not account for pooling areas. Pooling areas do not flow through the system the same as WIT. The volume of pooling areas should be measured separately and factored into basin volume as a “one-time fill”.

Example (refer to illustration above):

5' in Length (1' + 2' + 6" + 1' + 6") x 2' in Width x 0.25' Average Depth x 7.48 Gallons / ft.³ = 18.7 Gallons ( WIT)

Calculating Your Basin Size

Your basin should be sized in relation to the amount of water in transit. To keep the pump from running dry and to compensate for the water lost due to evaporation, the basin will need to hold 1.5 times the water you have in transit. Using the formulas provided will ensure that your Basin Total ft.³ either equals or exceeds Minimum Required Basin Total ft.³

WIT x 1.5 = Total Minimum Gallons of Water Required in Basin

Total Minimum Gallons of Water Required in Basin x 7.48 Gallons per ft.³ = Minimum Required Basin Total ft.³

Length of Basin x Width of Basin x Depth of Basin = Basin Total ft.³

We recommend using 2.5 times the WIT in the formulas above and to use Pond Free Blocks to account for any and all variables. Pond Free Blocks will be used to build the basin area and will be included in the majority in our kits. Each block will hold 31.5 gallons. Take 2.5 times your water in transit and dividing it by 31.5 will tell you how many blocks to use in your basin. While other options are available to use when building the water containment, we recommend using the Pond Free Blocks.

Example (refer to illustration above):

WIT = 18.7 Gallons

18.7 Gallons (WIT) x 1.5 times WIT = 28.05 Minimum Gallons of Water Required in Basin

3' Length of Basin x 3' Width of Basin x 1.5' Depth of Basin = 13.5 Basin Total ft.³

Without Pond Free Blocks: 13.5 Basin Total ft.³ x 7.48 Gallons per ft.³ x 0.3 average gravel void space = 30.3 Gallons of water in void space

With Pond Free Blocks: 13.5 Basin Total ft.³ x 7.48 Gallons per ft.³ x 0.96 Pond Free Blocks void space = 96.9 Gallons of water in void space

The Advantage of Using Pond Free Blocks

Pond Free Blocks work well in a variety of features. They are excellent when used in a bog filter and, most commonly, when building a basin for a Pond Free system. With 96% void space, the blocks can hold more water in a smaller space while still being able to support pavers, gravel, and other landscaping. Quickly lock the Pond Free Blocks panels in place and they are ready for installation. Pond Free Blocks save space and money by decreasing the volume of rocks needed and ensuring plenty of water to keep the pump from overheating.