Soakaway Sizer: BRE 365 Design
Percolation test & drainage
$9.99 · Designed for iPad. Not verified for macOS.
Size a domestic soakaway to BRE Digest 365 and see every step of the working. No sign-in, no ads, works offline in the field. Pay once, own it.
Soakaway Sizer - The BRE 365 Calculation That Shows Its Working
Planning conditions and Building Control ask for a soakaway designed to
BRE Digest 365. The alternatives are a spreadsheet at your desk, a web
calculator that charges per report, or a consultant at several hundred
pounds per design. Soakaway Sizer runs the full BRE 365 method on your
phone, offline, next to the trial pit, and shows the chain of reasoning
behind every number so the design can be checked and defended.
HOW IT WORKS
Enter your percolation test results (pit dimensions and timed drop, or
an infiltration rate you already have), the impermeable area draining
to the soakaway, and the design rainfall. The app evaluates the
1-in-10-year storm across the full range of storm durations, takes the
worst case as BRE 365 requires, and sizes the storage - showing every
step, so you can check the working rather than trust a black box.
WHAT IT CALCULATES
- Soil infiltration rate f from your percolation test, with the lowest
of your test runs governing the design
- Warnings when the ground is likely unsuitable for infiltration
- Required storage from the full storm-duration sweep, with the
governing duration identified, not a single guessed storm
- Optional climate change uplift on design rainfall, as many local
planning authorities now require
- Storage provided by crate/modular and rubble-filled constructions,
using the appropriate void ratio, with manufacturer override
- Works both ways: enter dimensions and check compliance, or enter
your site constraints and get suggested sizes
COMPLIANCE, LINE BY LINE
Clear pass/fail lines for the checks an inspector looks for: half
drain-down within 24 hours, minimum 5 m from buildings and 2.5 m from
boundaries per Approved Document H, and prompts for made ground and
groundwater.
WHO IT IS FOR
Groundworkers, drainage contractors, self-builders and builders dealing
with planning conditions, percolation tests and Building Control
submissions - and anyone who wants to see the method, not just the
answer.
A DESIGN AID, NOT A DESIGNER
Soakaway Sizer is a calculation aid. It does not replace the judgement
of a competent person, and every design should be verified by one
before construction. Calculations follow the method of BRE Digest 365
(2016); the app is not certified, approved or endorsed by BRE.
PRIVACY
No sign-in, no ads, no tracking. Works fully offline. Your data stays
on your device.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
The developer, Plan CD, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Rik Watson
- Size
- 865.3 KB
- Category
- Utilities
- Compatibility
Requires iOS 26.0 or later.
- iPhone
Requires iOS 26.0 or later. - iPad
Requires iPadOS 26.0 or later. - Mac
Requires macOS 26.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 26.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © 2026 Rik Watson, Omega Point Ltd.
