When most people think about protecting their swimming pool, they think about water chemistry, pool covers, or keeping the filtration system maintained.
Very few people ever think about what’s happening underneath the pool.
Yet one of the greatest forces acting on any in-ground swimming pool doesn’t come from inside the pool at all — it comes from the ground beneath it.
It’s called hydrostatic pressure, and understanding how it works could save a pool from significant damage in the future.
At Compass Pools, we believe the best engineering is often the engineering you never see. That’s exactly why we developed HydroPro™ — our exclusive hydrostatic protection system.
What is hydrostatic pressure?
Hydrostatic pressure is the pressure created by groundwater pushing upwards beneath your swimming pool.
Most of the time, this pressure isn’t an issue because the weight of the water inside the pool balances the pressure from below.
Problems arise when groundwater levels increase or the water inside the pool is removed. This can happen during:
- Heavy rainfall
- Flooding
- High natural water tables
- Burst water mains
- Underground plumbing leaks
- Excessive garden irrigation
- Water runoff from neighbouring properties
- Draining your swimming pool for maintenance or repairs
- Using pool water during emergencies such as firefighting
When the pressure underneath the pool becomes greater than the pressure inside it, enormous upward forces can be placed on the shell. Without an effective way to relieve this pressure, the structure of the pool can be compromised.
Every fibreglass pool needs hydrostatic protection
Whether it’s a fibreglass pool, concrete pool or another type of in-ground pool, hydrostatic pressure needs to be managed.
Most fibreglass pools rely on a small hydrostatic relief valve fitted into the floor of the pool. These valves have been the industry standard for many years and perform an important role.
However, at Compass Pools we asked ourselves a simple question:
Is there a better way?
Because when one small plumbing fitting is responsible for protecting your entire swimming pool investment, we believed there should be a more advanced solution.
The limitations of traditional hydrostatic valves
A conventional hydrostatic valve is typically a standard 50 mm plumbing fitting. While functional, it has several practical limitations.
Limited water flow
During significant groundwater events, the amount of water a traditional valve can pass is restricted simply by its size. The slower groundwater can escape, the longer pressure remains beneath the pool.
Delayed opening
After sitting inactive for months — or even years — the sealing surfaces inside a conventional valve can require additional pressure before they open. This means pressure may continue building before relief begins.
Dirt and debris
Like any component installed underground, hydrostatic valves can be exposed to dirt, sand and construction debris. These contaminants may affect how consistently the valve operates over time.
Resealing reliability
Once pressure has been relieved, the valve must close again to prevent unwanted water movement. Some traditional designs don’t always reseal as consistently as they should.
Introducing HydroPro™ — exclusive to Compass Pools
Rather than simply improving the existing valve, Compass Pools took a completely different approach.
HydroPro isn’t just another hydrostatic valve. It’s an engineered hydrostatic pressure management system designed specifically to protect fibreglass swimming pools.
Every aspect of HydroPro has been developed to improve how groundwater pressure is managed beneath your pool.
How HydroPro™ works
HydroPro continuously sits beneath your pool, requiring no electricity, sensors or maintenance. It simply uses water pressure itself to determine when it needs to operate.
As groundwater pressure begins to rise beneath the pool, HydroPro is designed to respond quickly, allowing groundwater to flow through the system and equalise pressure beneath the shell.
Once conditions return to normal, HydroPro automatically reseals.
The entire process happens without any input from the pool owner. Most homeowners will never even know it has operated — and that’s exactly how it should be.
Why HydroPro™ performs differently
HydroPro has been engineered to respond to relatively small increases in groundwater pressure. By responding earlier, pressure can begin equalising before excessive loads are placed on the pool shell. Rather than waiting for pressure to become significant, HydroPro is designed to act sooner.
Greater flow capacity
One of HydroPro’s biggest advantages is its substantially larger internal flow path. This allows significantly more groundwater to pass through compared with a conventional 50 mm hydrostatic valve. Greater water flow means pressure beneath the pool can equalise faster during sudden groundwater events.
Reliable automatic operation
HydroPro has been engineered to open when required and automatically reseal as groundwater pressure returns to normal. Its operating mechanism has been specifically designed for dependable long-term performance through repeated operating cycles.
Engineered for real conditions
Swimming pools exist in real environments — not laboratories. Groundwater can carry fine sand, soil particles and construction debris. HydroPro has been engineered with these conditions in mind, helping minimise the influence of debris while maintaining reliable operation over the life of the pool.
No electricity. No sensors.
One of the best things about HydroPro is its simplicity. There are:
- No electrical components
- No switches
- No sensors
- No programming
It simply remains ready to work whenever nature demands it.
Why we developed HydroPro™
At Compass Pools we’ve spent decades refining every aspect of fibreglass pool construction. Our philosophy has always been simple:
If there’s a better way to engineer something, we’ll build it.
Many innovations in swimming pools are obvious — self-cleaning systems, heating, lighting, automation. HydroPro is different.
You’ll probably never see it. You’ll hopefully never need to think about it. But when groundwater conditions change unexpectedly, it may become one of the most important engineering features in your entire pool.
Peace of mind beneath the surface
Buying a swimming pool is a long-term investment. While most people understandably focus on colours, shapes, water features and landscaping, it’s often the engineering hidden beneath the surface that determines how well your pool performs over decades.
HydroPro is one of those hidden features. It’s designed to quietly protect your investment, automatically responding to changing groundwater conditions without intervention, maintenance or power.
It’s another example of Compass Pools’ commitment to engineering products that aren’t simply built to look exceptional — but built to perform exceptionally for years to come.
Because the most important protection for your swimming pool shouldn’t rely on just another 50 mm plumbing fitting.
Frequently asked questions
Do I need a hydrostatic valve on a fibreglass pool?
Yes. Every in-ground fibreglass pool needs some form of hydrostatic pressure relief. Without it, a rising water table can push against an empty or partially-drained shell with enough force to damage or displace the pool. The industry standard is a simple relief valve. HydroPro is our engineered alternative — designed to respond earlier, flow more water, and reseal reliably.
Does HydroPro™ need power or ongoing maintenance?
No. HydroPro operates purely on the pressure difference between the groundwater below and the water in the pool above. There’s nothing to plug in, no batteries, no sensors, and no scheduled servicing.
What happens if I drain my pool for repairs?
Draining a pool is one of the highest-risk times for hydrostatic damage — the water in the pool is what usually holds the shell down against groundwater pressure below. Before draining any fibreglass pool for maintenance or repairs, always speak to your pool builder about whether it’s safe to do so, and what steps need to be taken to protect the shell while it’s empty. HydroPro is designed to keep working during these events, but a full drain is still something that needs proper planning.
Is HydroPro™ available on every Compass pool?
Yes — it’s a standard-fit feature on every new Compass fibreglass pool we install in Newcastle, the Hunter Valley, Lake Macquarie and Port Stephens. If you’d like to see one in person before you make a decision, drop into our Tomago display centre.
Can HydroPro™ be retrofitted to an existing pool?
Because HydroPro sits beneath the pool shell, it’s designed to be installed during the original pool build. Retrofitting isn’t practical on an existing installation, which is why the technology you choose before the pool goes in the ground matters so much.