01
When groundwater rises
Sustained rain, flooding, a high water table or changes around the site can raise groundwater outside an in-ground pool.
Protection beneath the surface.
An integrated safeguard for in-ground fibreglass pools, HydroPro is designed to respond when groundwater pressure rises outside the shell.
What rises outside the pool matters beneath it
HydroPro is Compass Pools' patented hydrostatic relief system, designed to respond when groundwater pressure rises outside an in-ground fibreglass pool shell.
02
Pressure acts on the shell
When the outside groundwater level sits above the water inside the pool, the difference can load the fibreglass shell.
03
Protection works as a system
A responsive valve complements the site assessment, drainage, installation and owner guidance developed for the project.
How it works
How pressure is released before it keeps building
HydroPro responds to the difference between groundwater outside the shell and pool water inside it.
Groundwater rises outside the shell
Heavy rain, flooding, a high water table or changes around the site can raise the water level in the ground surrounding an in-ground pool.
A pressure difference develops
When the external groundwater level rises above the pool water level, that difference can load the outside of the fibreglass shell.
HydroPro opens to equalise pressure
The valve responds to the pressure difference and allows groundwater into the pool, helping the levels equalise before the load continues to build.
The valve reseals after the event
Once the pressure has equalised, HydroPro is designed to return to a sealed state so the pool can continue operating as intended.
Measured under controlled conditions
The May 2026 comparison assessed when each valve opened and closed, how much water it admitted and whether it resealed under two pressure conditions.
- Measured or achieved
- Higher threshold or lower flow
- Not achieved
Independent technical review
The engineering behind HydroPro.
Spiros Dassakis of NextGen Experts brings together the valve design, installation requirements and comparative testing reported by mechanical engineer Angus Foley. The results below show how HydroPro performed against the two comparison valves under the conditions tested.
The full document includes Foley's test report and Charles Rickard's engineering opinion, with his co-inventor disclosure.
Read the technical review (opens in a new tab)
PDF · 22 pages · 1.1 MB
Test measure
HydroPro
Patented Compass valve
Valve sample 1
Commercial comparison valve
Valve sample 2
Commercial comparison valve
Activation and relief
Opening head differential
23 mm
290 mm
290 mm
Closing head differential
7 mm
230 mm
50 mm
Average measured flow
375 mL/s
30 mL/s
20 mL/s
Historical 30 mm opening benchmark
Achieved
Not achieved
Not achieved
Resealing observations
Positive external head
Sealed
Leakage observed
Sealed
Reverse head
Sealed
Sealed
Leakage observed
Stable in both conditions
Yes
No
No
Testing was conducted on a Compass-developed apparatus at the Compass Pools Australia manufacturing facility. Mechanical engineer Angus Foley independently reviewed, observed and reported the May 2026 procedure and results. Findings apply to the valve samples, apparatus and controlled conditions tested; they are not product certification against a nominated Australian Standard. Figures are approximate. The 30 mm reference is a historical engineering benchmark, not a current compliance requirement. Swipe sideways to see every column.
Whole-pool planning
Read the block before the pool
Enchanted considers the site, levels and project conditions before the pool and its surrounding works are finalised.
Read the block before the pool
Enchanted considers the site, levels and project conditions before the pool and its surrounding works are finalised.
Whole-pool planning
Hydrostatic protection answers
Checking groundwater on your site? Get a Quote
Risk can increase after sustained rain, flooding, changes in groundwater or drainage, and when a pool is partly or fully emptied. The site conditions and the difference between the water inside and outside the shell both matter.
Your pool, thoughtfully built
Start with a clear plan.
Tell us what you have in mind and Enchanted Pools will help shape the right fibreglass or custom concrete direction for your home.
Or call (03) 5922 2043