Flooding and Swimming Pools

Water caught between the pool wall and liner can cause the liner to ‘float’

What to do if water gets behind your inground pool liner?

If your home has been subject to heavy rainfall, and water has gotten behind your pool wall, you may find your liner appearing to lift. The photo above is a worst case scenario, caused by major flooding, but gives a great (extreme) visual example. Water getting behind the pool wall is rare, but it can happen to any pool type, and the effects vary. While a vinyl liner can ‘float’, a fibreglass pool can pop right out of the ground! If water gets behind a pool liner, it can lose its seal - this allows wrinkles to form and the liner to develop soft spots. If this occurs, the liner can then lift and float. If this happens to you – don’t panic, and don’t start swearing at your pool builder – he hasn’t done anything wrong! Mother nature is the culprit, and the good news is, if the liner is still in good condition, it can usually be put back in place.

It is important to identify the issue and follow steps to rectify it.

Steps to rectify a floating pool liner

  • Do not drain the pool. Draining the pool at this time could cause structural problems for the pool itself.
  • Lower the pool water level to the normal operating level as water can get behind the liner if the pool over fills.
  • Locate the “vacuum pipe” and check if it is free flowing. If the pipe is blocked , un-block it and allow it to self drain the water from behind the liner.
  • Using a pool broom, gently push the liner back to its original position as the water drains from behind the liner.
  • Prevent the pool from over filling and continue to keep the vacuum pipe free flowing to self drain the water behind the liner.
  • Employ a pool liner professional to check the pool liner is positioned correctly after the event.

Understanding how it happens

Pool liners are fastened to the top of the pool, and held tightly in place by the weight of water. When a pool liner is first installed, the air between the pool structure and the underside of the liner is usually removed with a vacuum to adjust the position of the liner. Then water is added and it is actually the weight of the water that holds the liner in place.

When water gets behind the liner through seepage of ground water, over-filling or flood, the water pressure equalises on both sides of the liner and the liner can move. This is commonly called a “floating” liner. Issues with ground water are not unique to vinyl liners - ground water has been known to lift whole pools out of the ground if the surrounding drainage is not sufficient. Fibreglass style pools and even concrete pool shells have been known to “pop up” or move in severe ground water situations.

A floating liner is still fastened at the top, but has some water underneath to where wrinkles start to form. The corners of the wall to the floor and the deep end will be “spongy” and “soft” when pushed with a pool broom.

Once the water source has been removed, the water will slowly drain away, but it is important to ensure the liner goes back in the same position during this time. This can be done using a pool broom to gently move the liner outward toward the wall as the water drains away from behind the liner. It may take a few weeks for the water to self drain away depending on how much ground water is present.

Alternatively, you can remove the water through the “vacuum pipe” if one has been installed when the pool was built. Or better still, call your local pool professional and they can drain and re-fit the liner correctly, and even advise on fitting preventative measures to avoid the problem in the future.

How to use the vacuum pipe

Most inground vinyl lined pools should have a pipe that connects the void behind the liner to a drain or some external point which is used during the initial installation of the liner as well as for removing water accumulated behind the liner and other service tasks. This pipe is commonly referred to as a “vacuum pipe” and should be installed so the outlet is at least 450mm (18”) below the normal pool operating water level so it can be self draining. Sometimes due to a level site, there is no option but to have the outlet for the liner “vacuum pipe” below the water level and therefore it may be plumbed to the suction side of the pool pump or to a storm water drain.

If the pipe has been connected to a storm water drain, it should have a non return valve so that in times of heavy rain, the water does no flow back in behind the pool liner. Sometimes these are not installed and other times the non return valve can fail and cause a large amount of water to flow behind the liner and the liner to “float” and become wrinkly and spongy. If you suspect the pipe is connected to storm water, locate the pipe and disconnect it from the storm water pipe to prevent the water flooding in behind the pool liner. Install a non return valve and then reconnect it.

If the pipe has been connected to the pump suction inlet, it would have been installed with a 3-way valve and the valve needs to be opened whilst the pump is running to suck the water from behind the liner. Whilst the water is being sucked from behind the liner, use a pool broom to gently push the liner back into position so there are no permanent wrinkles left behind. If there are wrinkles, they can only be moved by draining the pool down to the level of the wrinkles. This is best done by an experienced liner installer or service person.

To find a local pool liner professional, enter your postcode in the ‘find a supplier’ box and submit.

What to do if your pool is actually flooded

My pool has been inundated with flood water. What do I do?
In this instance, your first priority is health and safety - ie electrical safety, construction integrity of the pool, fencing stability and water contamination through debris. Once all these issues have been assessed, only then can you begin work to restore the pool back to a usable condition. The Northern Territory Government have an excellent Fact Sheet with regard to flooded pools, which you can download here at www.nt.gov.au

FAQs

Q. My liner has just developed wrinkles, what does this mean?
A. This indicates there is water under the liner caused by ground water or damage to the liner.

Q. My liner is soft and spongy in the corners, what caused it?
A. This indicates there is water under the liner caused by ground water or damage to the liner.

Q. How do I remove water from behind my pool liner?
A. Locate the “vacuum pipe” and ensure it is clear and if it does not self drain, then you can suck water from this pipe to remove from behind the liner.

Q. The water has drained from behind the liner but now the liner has wrinkles that I cannot move, what do I do?
A. You need to contact a liner professional as they may need to partially drain your to re-position the liner and remove the wrinkles for you.

Q. Does the liner moving cause any permanent damage?
A. Depending on the age of the liner. If the liner is old and brittle, then as the water behind drains away, it may cause enough stress to tear the liner.

Q. My pool liner has water behind it. Do I need to buy a new one?
A. No, most liners that are not too old will be able to be re-fitted by a pool liner professional.

Q. Is my floating liner covered by my pool liner warranty?
A. No, the floating liner is not covered by the liner warranty, nor is it a fault of installation. It is usually a result of an extreme weather condition and therefore may be covered by insurance. Check with your individual policy details or talk to your insurance company.