In this article, we are going to break down a couple of things to understand about swimming pools, to ensure your pool doesn’t end up like this new ‘above ground’ pool. The first mistake can come from the process of draining a pool of it’s water. Draining a swimming pool can be risky, problematic and should only be done only when absolutely necessary. Why? Because swimming pools are always meant to be filled with water, they are designed and built to have a massive amount of weight.


The heavy weight and pressure of the water keeps the pool in place. Removing water from a swimming pool can cause serious damage to pool walls, floors and liners if not done correctly or done at the right time.


In some instances, pools can ‘pop’ out of the ground or shift, while others may cave in. There may also be damage to decks or paving surrounding the pool, wiring as well associated equipment such as plumbing, lights and in-floor cleaning systems.




Most swimming pools have at least one hydrostatic valve fitted the deepest part. Some pools have more than one.


Hydrostatic valves are designed to let ground water into the pool caused by hydrostatic pressure. The hydrostatic valves do this by releasing and stabilising the water pressure under the pool with pool itself to avoid any damage made by high water tables that can be due to draining, geology (water tables (aquafers) or heavy rainy periods.


Hydrostatic valves need to be inspected from time to time to ensure they are working. In some instances, they can be removed to allow greater release of hydrostatic pressure.


It is recommended that a hydrostatic valve be replaced if it is not working or is tampered with.




Some (Fibreglass mostly) pools may have an inspection pipe(s) near the pool, usually about a metre from the pool edge.  These would have been installed at the time the pool was placed in the ground to check ground water levels near the pool.


Standpipes are usually closed off with something like a shower grate to stop too much rubbish filling them up.  You can usually check the ground water level by inserting a thin dowel or stiff wire down and then measuring the depth.  As a guide if the water level shows as being LESS than about 1.5 to 1. 8 M below ground level, be careful when emptying the pool. It may cause movement or bulges.


There are risks to draining a pool. In this regard, some contractors prefer not to empty a pool themselves but provide advice or guidance to the customer to do this themselves only for the contractor to return to undertake works. This may be seen as professional advice and could have legal implications for contractor if the customers pool is damaged based on advice they proved to the customer.




Whilst draining a pool may be required in some instances, it is not normally required nor recommended as routine practice.


A risk assessment of a pool and its surrounds should always be done before accepting a job, providing a quoting or draining. If in doubt, do not proceed and seek out expert advice.


If you are not sure – do not proceed and seek out professional advice. The profit gained from undertaking an acid wash or other similar works is negligible if things turn bad due to poor planning, practice or negligence.




  1. Do not drain a pool during extended periods of heavy rain
  2. Ensure that the Hydrostatic Valve is working before you start draining
  3. Pump any discharge into the sewer (check with your local council for rules) and far away from the actual pool
  4. Make sure pool is sufficiently braced or OK’d by expert before draining
  5. Drain water slowly and monitor
  6. Once drained, work as fast as you can – Do not leave pool unattended
  7. Make sure your insured as even an expert approach can turn bad


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This communication contains information and data prepared by SPASA Australia. The information and advice published or made available through SPASA Australia is provided for your general information only. Every swimming pool or spa installation is different and pool and spa builders, service technicians and other professionals should seek independent expert advice in relation to a particular pool or spa installation. The information contained in the document is provided for informational, educational and learning purposes only and is not a substitute for professional advice.