• +1 (888) 818 POOL
  • swimmingpoolsteve@gmail.com

Vinyl Pool Liner Problems

Vinyl liner problems
Vinyl swimming pool liners are not what they used to be. Literally. Going back a generation or two vinyl pool liners used to last upwards of 25 years...good luck getting anywhere near to that kind of life out of a modern day pool liner. So what happened? Is this just a result of a throw away culture where products are manufactured to be as cheap as possible? Well, yes, but also a vinyl pool liner is not what it used to be - and that is actually a good thing!

If you want your pool liner to last as long as possible then all you need to do is add a bunch of chemicals to the vinyl which are not congruent with sustained human life. Vinyl liners used to have a lot more chemical additives than liners that are made today. These additives certainly increased the longevity of the liner...but at the expense of the safety of the water and the people in it. This is a very complicated subject and one that you should speak with your doctor about, not your resident pool expert, if you have concerns that you would like to address. From the pool side of things there are a lot of chemicals used in vinyl sheet manufacturing that are restricted or heavily regulated. So much so that vinyl sheet manufacturing has been almost completely outsourced to Countries where environmental protection and control are not as strict as Canada and the USA.

A vinyl liner produced in the 1960's to 1980's in North America could have a service life of 25 year or more. I have personally worked with a liner older than 30 years old. In the perspective of a modern day pool liner, well, you simply will not have a modern day liner last this long. Or anywhere near to this long really. There are a host of reasons (chemicals) for this but one of the biggest, most important chemical differences between modern day liners and older generations of liners boils down to the use of plasticizers.

Plasticizers In Pool Liners

Plasticizers are chemical additives added to plastic to allow them to be more malleable instead of rigid. As you might imagine, a pool liner needs to be specifically malleable and as such plasticizers are an important chemical in vinyl sheeting. Phthalates (pronounced thal-ates) are plasticizers used in vinyl pool liner manufacturing and ones with a very dubious reputation among people sensitive to chemical exposure.

Phthalates are considered an environmental pollutant and are potentially tied to a host of terrifying medical concerns. This, among many other chemicals used in vinyl sheet manufacturing, is the reason why almost all pool liners purchased these days will be from vinyl sheeting produced outside of Canada or the USA. The cost of safe handling and disposal of toxic manufacturing byproducts is simply too expensive to remain competitive within the market. A Country that has more relaxed, or zero, regulation of dangerous and environmentally damaging toxic substances will simply be able to produce vinyl sheeting for less money than a Country where strict oversight and control of toxic substances consumes profit margins.

Pool liners that used to last 25 years on average had much higher levels of plasticizers than in use today. Additionally over the past 60 years over 30,000 chemicals have been used for the purposes of plasticizing...but in modern day manufacturing only about 50 are still used. While some plasticizing chemicals may have been able to produce a longer-lasting pool liner, the environmental risk or chemical toxicity of these products preclude them from use with modern day standards.

BPA (Bisphenol A) - BPA is an organic synthetic compound and specifically not a plasticizer. A plasticizer is something that is added to a plastic to change the physical properties of it. BPA on the other hand is a monomer which is used in the chemical process of polymerization. In the making of a polymer over 99% of the BPA will become permanently bound. Trace levels of free BPA or "residual BPA" are possible and are often a concern for swimming pool owners and health conscious individuals. It is unlikely that BPA is a concern for swimming pool owners based on the scientific study of safe BPA levels for humans. Plasticizers, in general, pose a much greater concern for health than BPA's.

Pool liners also used to contain heavy metals such as lead and arsenic as well as formaldehyde, styrenes and other toxic chemicals which are restricted in use, or altogether banned, from modern day manufacturing processes.

UV Inhibitors In Vinyl Pool Liners

One of the most expensive chemicals used in vinyl pool liners are UV inhibitors. UV kills pool liners, causes them to shrink and become brittle, and strips the color from the vinyl. In order to prevent (or at least delay) this damage, UV inhibitors are added during the vinyl sheet manufacturing. The amount of UV protectants used will have a great deal to do with how long your pool liner will last. The thing about UV inhibitors is that they are expensive.

One of the biggest, most tangible differences between "cheap vinyl" and "expensive vinyl" is the amount of UV protection in it. When you have a bunch of vinyl liner choices, and one is much cheaper than another, this is likely one of the main things that you are trading off for a cheaper price. Inground pool liners have more UV inhibitors than above ground pool liners. This is one of the main reasons that inground liners are more expensive than above ground liners (assuming the same liner thickness and square footage).

It is a misconception that vinyl from certain Countries is inferior to another. Vinyl sheeting manufactured in Canada, Brazil, Europe, China or anywhere else all can be the same quality...it all comes down to price. When the vinyl roll is ordered the amount of plasticizer and UV inhibitor is specified. The higher these numbers - the longer the liner should last. People often think that vinyl coming from China is cheap and inferior...and it certainly can be if you are shopping for the cheapest possible materials to work with. What you need to determine is the quality of the products that you are dealing with and this can be a very difficult (or at least confusing) question.

Country Of Origin For Vinyl Pool Liners

USA made liners from China
You certainly do not need to look far to see big, bold claims about where your pool liner has been made. Unfortunately, in most cases, this is just cleverly worded marketing to get your money. When I worked in wholesale distribution I had direct contact with liner manufacturers and if you are not asking the right questions then you are not getting straight answers. For example:

Pool Guy - Where is this liner made?

Liner Manufacturer - 100% made in the USA

That sounds pretty good right? USA made products have a strong reputation and supporting your local economy is always an easy sell from a marketing perspective. Instead of asking the question that the manufacturer wants you to ask, consider asking different questions to get the real answers that you need:

Pool Guy - In what Country was the vinyl sheeting used for this liner manufactured?

Liner Manufacturer - Jiangsu China

Pool Guy - Then why did you tell me this liner was 100% made in the USA?

Liner Manufacturer - Once we buy the materials and import them from China we make the liner here in the USA

Does this seem at all misleading to you? It sure does to me and yet this is exactly how the swimming pool industry works. When you are speaking with your sales representative, or your liner manufacturer directly, then ask them to direct you to which liners use 100% virgin vinyl that is manufactured AND produced in your home Country. Most liner manufacturers will offer multiple vinyl stocks that your liner can be made from. Most of these stock will come from China but there are usually a few choices in each liner catalog for liners wholly produced within your Country.

You should note that I am not saying that vinyl manufactured offshore is inferior. What I am saying, based on my professional experience with thousands of liner installations and tens of thousands of vinyl liner pool inspections, is that vinyl produced offshore is not as reliable as vinyl manufactured within Canada or the USA. This could be due to vinyl being ordered like this, cheap, or it could be that a lack of regulation means products are not being delivered as ordered. You can not exactly lick a sheet of vinyl like a nine volt battery to see how much UV inhibitor or plasticizer is in it. There have been a lot of problems with inferior vinyl hitting the market in Canada and in the USA which came from overseas and this has resulted in some uncommon issues starting to become common:

Vinyl Fading - Fading vinyl is one of the biggest concerns with inferior vinyl sheet manufacturing, specifically lower levels of expensive UV inhibitors were used to make the vinyl roll. Whether the vinyl was ordered with lower levels of UV inhibitor to save money, or whether the ordered amount of UV inhibitor didn't make its way into the finished product, is the real question. In almost every case of this I have seen only part of the liner stock fades which means that not all vinyl rolls have the same amount of UV protection. While there is plenty of high quality vinyl stock coming from China, there is also enough problems like this to be a concern.

Vinyl Staining - Vinyl liners are supposed to be resistant to staining from problems like poor water chemistry, dirt or the presence of metals either on the liner directly or suspended within the water. Lower quality vinyl will stain much easier than higher quality vinyl that has stain inhibitors built into it and once the liner is stained it will be difficult to remove the stain.

How Thick Is A Vinyl Pool Liner?

Vinyl liner thickness
This is one of those questions that pool owners get hung up on. You are certainly right that the thickness of your vinyl matters but would you know the wrong answer if you heard it? How thick is a liner supposed to be anyway? Before this question can be answered we must first agree on a unit of measurement.

Mil - A Mil is a standardized unit of measurement which correlates specifically to 1/1000 of an inch.

Gauge - Gauge is a relative term and not defined by a specific measurement

So what are you looking for in a pool liner? Inground pools are made using 27 Mil vinyl liners. Above ground pools are made using 20 Mil vinyl liners. There are exceptions to this however this is the standard to which you should be comparing. When someone says 30 Mil most of the time you are not actually getting a 30 Mil liner...you are getting a 27 Mil liner. When anyone describes pool liner thickness in gauge, this is a clear indication to me that they do not understand how liner thickness is measured, or they are attempting to make their own product sound better than the next guy.

Another problem is that a pool owner may ask about the thickness of a liner...but do you think that anyone actually measures their liner thickness once installed? Well...I do and I have been doing this for years. The results are not encouraging to say the least. The thing about liner thickness is you can easily check for yourself just how thick it is using a set of calipers. I have measured over 100 liners from multiple manufacturers and Countries of origin. When a liner is advertised as 27 Mil liner most often it will actually measure anywhere from 22 to 27 Mil.

What I would suggest for all liner installers like myself who are serious about quality and getting what I pay for is to start checking your liners. Every main drain and return that you cut out after liner installations should be tagged with the date and install location with a permanent marker. I like to keep and measure these cut-outs for thickness. If you start doing this also you will soon discover that not all liners are created equal.

Wrinkles In Vinyl Liners

It is well known within the pool industry that a vinyl liner can be ruined by poor water chemistry. The holy grail of vinyl liner problems are "pH wrinkles" which are a sudden onset of small, permanent wrinkles, throughout the entire pool. These wrinkles are caused by a chemical change in the vinyl that the liner is made from which results in the liner absorbing more water than it should. This causes a net increase in the physical size of the liner. Since the liner is already fit to the pool, and with the weight of the pool water preventing the liner from shifting, wrinkles form to accommodate the increased size of the liner. Once these specific wrinkles form they will never go away and replacement of the liner is the only recourse.

Low pH - Low pH has always traditionally been the cause of permanent wrinkles in a pool liner due to increased water absorption by the liner. Not to worry, periodically letting your pH slip below 7.0 is not going to cause this, but sustained periods with very acidic pH can potentially cause this. The lower the pH gets the more likely that wrinkles will form in your liner.

High Sanitizer - High sanitizer levels can also cause the chemical structure of your vinyl liner to change which results in three to five times the normal water absorption by the vinyl. As with wrinkles caused by low pH, water absorption wrinkles from high sanitizer levels will not go away once you correct the water chemistry issue.

Fortunately permanent wrinkles like this are relatively rare in vinyl pools and usually you have to miss the mark pretty far with your water chemistry to encounter this problem. Most of the time wrinkles in a vinyl pool are caused by temporary floating of the pool liner due to water under the liner either from elevated ground water tables around the pool, or potentially a leak within the pool itself. If you want more information about wrinkles in vinyl liner pools then read this article on pool liner wrinkles.

Liner Slipping Out Of Coping Track

As a pool owner it can be alarming to see your liner pulled out of the coping track. While problems like this are more common in older liners, even new liners can have this happen to them. Fortunately this is almost never a big concern and skilled hands can replace the liner back into the coping track with relative ease. Of course, every good pool technician knows that pool liners will lose their stretch as they get older, so the older a liner is the harder it will be to get back into the track. To help encourage the liner back into position usually boiling water will be used to increase the elasticity of the area that is being worked on. More times than not if you can get the liner back into the track this will permanently solve the problem.

Vinyl pool corner
When a liner slipping out of the track becomes more of a concern is when it keeps happening, or even worse, if you simply can not get it to go back into the coping track. Sometimes the coping track can stretch out which results in less purchase than the liner bead used to have. Also, sometimes the coping can be damaged in a subtle way that you did not notice at first. When you have a liner that will not stay in the track then you can look at adding a liner lock which is a soft plastic wedge to help retain the liner bead. Sometimes it solves the problem permanently but sometimes it can make the problem worse by stretching the coping out even further. Still, if your liner will not stay in the track then you need to do something or else you need to replace the coping and liner in your pool.

Sharp corners are the most problematic area when it comes to installing a liner, as well as putting a liner back into the track that has popped out. As vinyl ages the plasticizers escape or become damaged by UV and the vinyl itself shrinks. Where once the liner fit snugly into the corners of your pool you may find with an aging liner that it continually slips out of the coping track and no amount of professional encouragement can get it to go back in. Often pool owners will attempt to "remedy" this problem using duct tape, or some kind of crude vinyl patch, but if you have a liner that will not seat into the coping track around your entire pool then you need to replace the liner. All too often pool owners attempt to get "one more season" out of a failed liner. To find out why you should never try to get another season out of a liner that will not stay in the coping track you can read this article on how to get the most life out of your pool.

Draining A Vinyl Liner Pool

If I had a dollar for every time a vinyl pool owner told me they went ahead and drained their pool I would be a rich man today. So much so that it actually made my list of one of the 6 things you should NEVER say to your pool guy. If you are a vinyl pool owner then please note that you should always maintain a minimum safe water level in your pool of at least six inches of water in the shallow end. Failure to observe this minimum value, more times than not, will result in you needing a new liner...like immediately.

The shape of your pool, the angle of the long slope, the age of the liner, and the fit of the liner originally will all have an impact on whether your liner survives an impromptu draining. The conventional wisdom is that if you drain your vinyl pool without first putting vinyl installation vacuums on then you will ruin your liner. Some times you can get lucky but you certainly should not try to push your luck. Vinyl pools use strong vacuums behind the liner to hold it in place until the water level fills. Once the water level is covering the floor of the shallow end then the liner is unlikely to shift much and the vacuums are turned off.

If you find yourself in a situation where you must drain your vinyl pool then your two options are to call a vinyl liner company to come and install some liner vacuums that run for the duration of the time the water level is down. Or two, you can drain your pool to only six inches of water in the shallow end, which will be well more than half the volume of your pool, and then refill with fresh water. The dilution should be more than enough to resolve any water chemistry problems that you might be having. To make this point, I previously wrote this satire article about how to clean a dead body from your pool to prove the point that scooping, brushing, vacuuming and water chemistry is enough to solve almost all pool water problems, and the ones that can't be resolved this way can certainly be resolved via dilution. Never take it upon yourself to fully drain your vinyl liner pool.

Variable speed pool pump reviews

Pool and spa chemistry crash course

New pool owner guide

Proof of variable speed pump savings

Is salt water bad for pools?

The Swimming Pool Steve blog

Have a question - ask Steve

Swimming Pool Steve

If you want to continue learning about pools and spas from an industry expert follow swimming pool Steve on Facebook, Twitter and YouTube

Endorsed Brands From Swimming Pool Steve

The following links and products are to affiliates of the Swimming Pool Steve website. These are brands, products and services hand selected by Steve for endorsement. Please note that these endorsements can include monetary compensation, affiliate links and referral fees to Swimming Pool Steve, however there is zero additional cost to you should you use one of these products or services. Income generated from these links helps to keep this pool and spa resource available for everyone. To have your product or service considered for listing here as an endorsed brand email SwimmingPoolSteve@gmail.com.

Amazon Disclosure Statement - As an Amazon Associate I earn from qualifying purchases.


If you need to order swimming pool equipment, parts or chemicals online then you should choose to buy from a specialist that deals exclusively with pool and spa products. InTheSwim.com would be my recommendation to pool owners looking to shop online for pool and spa supplies.

- Swimming Pool Steve

Basecrete flexible bondcoat

I can not stress enough the importance of using a waterproofing solution for concrete swimming pools. When it comes to the technical process of waterproofing concrete pools Basecrete is the most effective product that I know of. I strongly endorse the use of Basecrete products to all concrete pool owners.

- Swimming Pool Steve

LightStream swimming pool financing

Pool installations can be very expensive especially when you start to add optional extras. Building a pool is a once in a lifetime event for most people and it is important to get the pool you want. Swimming pool financing can help you get the pool you want and make sure you have the money you need to do it right the first time.

- Swimming Pool Steve

Pool Supplies Canada

When it comes to ordering pool and spa supplies online in Canada www.PoolSuppliesCanada.ca is by far the best option. They carry everything from chemicals to replacement pumps to entire pool kits, with free shipping options and more "in stock" items than any other Canadian online retailer.

- Swimming Pool Steve