Free to size. Building Control-ready PDF £25 +VAT (£30 inc VAT).
Runs in your browser. Enter your percolation test, choose the construction, read off the size.
What a concrete ring soakaway is
A concrete ring soakaway is a shaft of perforated precast concrete rings, manhole-style, set in a bored or dug hole and surrounded by clean granular backfill. Water is stored in the open chamber and in the voids of the surrounding stone, then soaks out through the perforations and the base.
When to use one
It is the durable, maintainable choice — the open chamber can be rodded and inspected, and the rings last for decades. It suits larger domestic plots and rural sites where longevity and access for maintenance matter more than keeping the dig small.
How it's sized to BRE 365
BRE 365 sizes it on the storage available in the ring chamber plus the surrounding granular void. SoakMonkey accounts for the chamber volume, so the depth and number of rings it gives you actually hold the design storm.
Concrete rings are heavy and usually need plant to place, so allow for access. Fit a rodding or inspection cover, and a silt trap upstream to keep the perforations clear.
Free to size — pay only for the report
SoakMonkey is free to use: enter your percolation test, add the area draining to the soakaway, and read the size on screen for nothing. You only pay £25 +VAT (£30 inc VAT), once, when you export the Building Control-ready PDF — with the percolation analysis, the BRE Digest 365 storm table and the dimensioned result.
Frequently asked questions
What is a concrete ring soakaway?
A concrete ring soakaway is a shaft of perforated precast concrete rings, manhole-style, set in a bored or dug hole and surrounded by clean granular backfill. Water is stored in the open chamber and in the voids of the surrounding stone, then soaks out through the perforations and the base. It is the durable, maintainable choice — the open chamber can be rodded and inspected, and the rings last for decades. It suits larger domestic plots and rural sites where longevity and access for maintenance matter more than keeping the dig small.
How is a concrete ring soakaway sized to BRE Digest 365?
BRE 365 sizes it on the storage available in the ring chamber plus the surrounding granular void. SoakMonkey accounts for the chamber volume, so the depth and number of rings it gives you actually hold the design storm.
Is the concrete ring soakaway calculator free?
Yes — entering your percolation test and sizing the soakaway on screen is free. You only pay £25 +VAT (£30 inc VAT) when you export the Building Control-ready PDF.
Anything to watch on site?
Concrete rings are heavy and usually need plant to place, so allow for access. Fit a rodding or inspection cover, and a silt trap upstream to keep the perforations clear.
Other soakaway types
SoakMonkey sizes every common construction. Compare another:
Or back to the main soakaway calculator, size one for a house extension, or work out what size you need.