Soakaway Size Calculator Spreadsheet

This spreadsheet makes iterative soakaway design much quicker and easier, allowing the designer to complete an optimal design in minutes.

A soakaway is a tank or trench where water is stored and allowed to soak into the ground, rather than discharging to an outfall or sewer. Soakaways are often used in remote or isolated areas, where the existing drainage is not sufficient and would be expensive or difficult to upgrade, or where a SUDS system is being installed to reduce the runoff from a new development. For more details, we have a comprehensive soakaway pit design guidance section on this website.

Soakaway Design Spreadsheet

The design spreadsheet works by calculating the inflow into the soakaway in all design storm conditions. Then the spreadsheet calculates the outflow into the soil, and uses this to determine the storage area required. It then checks that the proposed soakaway is capable of storing the required volume of water and is capable of emptying the soakaway quickly enough.

The spreadsheet is suitable for non-professional users such as homeowners or farmers, particularly used in conjunction with the Ultimate Design Guide which includes all the information needed to complete an effective soakaway design. Further guidance for non-professional users in included on this website here.

The spreadsheet is also suitable for professional users. The unique calculations completed automatically by the spreadsheet allows the user to analyse every possible design storm from 5 minutes to 48hrs. The spreadsheet calculates the worst case and uses this to determine the required storage volume. A unique design graph is produced which allows the professional designer to optimize a BRE 365 compliant soakaway design in minutes.

Get the full license version now for only £10. This includes;

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Download Free Trial Version

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