Does Your Pool Have a Hydrostatic Valve?
If you own a swimming pool—or you’re planning to install one—you may have heard the term hydrostatic valve mentioned by pool builders or inspectors. But what exactly is a hydrostatic valve, and does your pool really need one?
Understanding this small but critical component can help protect your pool structure and save you from costly repairs in the future.
What Is a Hydrostatic Valve?
A hydrostatic valve (also known as a hydrostatic relief valve) is a safety feature installed in some swimming pools to relieve groundwater pressure beneath the pool shell.
When groundwater builds up under an empty or partially drained pool, it can create enough pressure to cause the pool to lift, crack, or shift. A hydrostatic valve automatically opens to allow water to flow into the pool, equalising pressure and preventing structural damage.
Why Is a Hydrostatic Valve Important?
Groundwater pressure is one of the most common causes of pool damage, especially in areas with:
High water tables
Heavy rainfall
Coastal or low-lying land
On the Gold Coast, fluctuating groundwater levels can increase the risk of hydrostatic pressure, making this valve an important consideration for many pool owners.
Without a functioning hydrostatic valve, a pool that is drained for maintenance or renovations can literally pop out of the ground—a problem known as “pool popping.”
Do All Pools Have a Hydrostatic Valve?
No, not all pools are fitted with hydrostatic valves.
Whether your pool has one depends on:
The type of pool (concrete, fibreglass, or plunge pool)
Local building codes at the time of construction
Soil conditions and groundwater levels
The builder’s design approach
Concrete pools are more likely to include hydrostatic valves, while some fibreglass or smaller plunge pools may use alternative drainage solutions.
How Can You Tell If Your Pool Has a Hydrostatic Valve?
In most cases, hydrostatic valves are located:
At the deepest point of the pool
In the main drain at the pool floor
To check safely:
Look for a round or slotted fitting in the main drain
Consult your pool’s construction plans
Ask a qualified pool professional to inspect it
⚠️ Important: Never attempt to remove or tamper with a pool drain yourself, especially if the pool is empty.
What Happens If a Pool Doesn’t Have One?
If a pool lacks a hydrostatic valve—or if the valve is blocked or faulty—it may be vulnerable when:
The pool is drained
Heavy rain increases groundwater pressure
Repairs or renovations are underway
Potential risks include:
Cracked pool shell
Structural movement
Complete pool lift
Costly repairs or rebuilds
This is why professional advice is essential before draining any pool.
Do Plunge Pools Need a Hydrostatic Valve?
Plunge pools are smaller, but that doesn’t mean hydrostatic pressure isn’t a concern.
Depending on:
Ground conditions
Pool depth
Construction method
A plunge pool may still require a hydrostatic valve or an alternative pressure-relief system. An experienced plunge pool builder will assess the site and recommend the safest solution.
Can a Hydrostatic Valve Be Added Later?
In some cases, yes—but it depends on the pool’s construction.
Retrofitting a hydrostatic valve into an existing pool can be complex and may involve:
Cutting into the pool floor
Structural assessment
Professional installation
If you’re unsure, a pool specialist can advise whether your pool is adequately protected or if upgrades are recommended.
When Should You Be Concerned?
You should seek professional advice if:
You plan to drain your pool
You notice cracks or movement
Your property has poor drainage
Your pool is older and documentation is unclear
A quick inspection can prevent major long-term issues.
Final Thoughts
A hydrostatic valve may be small, but it plays a critical role in protecting your pool from underground water pressure. Whether you already own a pool or are considering a new plunge pool installation, understanding how hydrostatic protection works is essential.
If you’re unsure whether your pool has a hydrostatic valve—or whether your site requires one—consulting an experienced pool professional is always the safest option.
