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How To Fix Pool Plumbing Leaks


Pool plumbing leaks, specifically leaks in the plumbing of the pool equipment, should not be fixed with epoxy. Epoxy seems to be the first thing that pool owners turn to when they discover a small leak from the plumbing fittings of their pool equipment. Epoxy is almost never the right choice to use for fixing leaks in pool plumbing systems.

Sometimes a leak on the equipment pad can be an indication that something has failed such as a crack in the filter tank (which would be dangerous) or a crack in the wet end manifold of the pool pump. If these are broken then you will need to replace the equipment. Attempting to patch pressurized equipment, especially the filter tank, with epoxy is not a good idea at best and a dangerous proposition at worst. In most cases however the leak will not be from the equipment directly but instead from the pipe connections to the equipment.


Threaded Pipe Fitting Leaks

Most commonly pool equipment that is leaking will be leaking from a threaded pipe fitting connection that has failed. This happens very often due to the day to day interaction with the pool equipment. Depending on the type of thread sealant that you have on the threaded connection you can inadvertently break the seal which will cause a leak that can not be fixed without taking the fitting off and replumbing it with a new application of thread sealant.

Silicone - Silicone thread sealant is a great choice for connecting pool equipment with threads. It is easy to work with and will almost always create a leak free connection provided that you use 100% silicone and not latex caulk. If you use this product you must let it set before turning the plumbing system back on or you can cause a leak to form. More commonly, during day to day use, or during winterization of the equipment, you can accidentally move the pipe connected to the threaded fitting. If the threaded fitting gets moved after the silicone has set then it will break the seal and begin to drip. Applying more silicone will not resolve this problem - you must unthread the fitting and apply a fresh layer of silicone and reinstall into the equipment.


Teflon tape - Also known as thread sealant tape is a stand alone option for threaded pipe connections or can be used in addition to silicone. The advantage of thread sealant tape is that if a leak develops at the threaded connection you may have the option to tighten the connection a small amount more which should resolve the leak. This would be one of the reasons to have unions installed into your plumbing - without a union you will not likely be able to tighten the fitting any further since the pipe is connected to something on the other end. If this is the case you will need to cut into the system and tighten the fitting. When reconnecting the pipe that you cut consider adding in a PVC union instead of a PVC coupling. In the future if this becomes a problem again then you can simply spin open the union, thread the connection a little tighter, and close the union. When choosing teflon tape as a thread sealant be sure to use the thinner material as opposed to gas line thread sealant tape which can work, but has a much higher chance of cracking the plastic manifold that you are threading into. A skilled hand can use gas tape but be sure to not over-tighten!


Pipe dope - If you use a petroleum based pipe dope thread sealant then you are at risk of breaking your pool equipment. Since pipe dope expands as it ages, as well as deteriorates PVC and ABS plastics, this can very likely cause a failure of your pool equipment since most is made from resin or plastic. You should never choose pipe dope for connecting pool equipment unless it is a teflon based pipe dope.


The best method to eliminate leaks on your first attempt is to use both teflon tape as well as 100% silicone. Apply three or four wraps of teflon tape to the male threads, in the correct direction, and then apply a liberal amount of silicone overtop of this. Thread the fitting in hand tight plus 1/2 a turn with a suitable wrench and let it set for 24 hours





Pool Pump Leaks


Most commonly you will notice a pump leak problem one day when you are not able to prime your pump for some reason. It could even be that the pump has been leaking for a long time and you didn't notice, or it seemed like a minor problem, but now that it will not prime you need to deal with it. There are a few common leak points for pool pumps so it is important to determine the nature of your leak. If you have a pool pump that is leaking, and it is not leaking from the pipe connections, then there are a few likely causes for the leak. First, if you are noticing water under your pump but are not able to locate the source of the leak, you very likely have a main seal leak on your pump. The main seal is in the middle of the pump and tends to cause small drips out of the bottom of the pump. If you have a leak in this location on your pump you will require a new main seal and pump service. If the pump is older or starting to make a humming noise then you may have damage to the pump bearings as a result of this leaking water. If this is the case you will need new bearings as well as a new main seal at which point you should at least consider replacing the pump completely - especially if it is already older.



If the leak is not from the pipe fittings, and not from a main seal then it is most likely that you have a leak due to the lid gasket being dry, displaced or missing. This would result in water escaping from the lid, sometimes, but usually would simply manifest itself as air running in the pump chamber. Use a silicone based lubricant on your pump lid o-ring at least once per year to help prevent leaks in this location. The final location that is common to leak on pool pumps is from the winterization ports. Check to make sure that the winterization plugs are tight but be careful as they are only plastic and will break fairly easily. The only other possible leak location would be from a crack in the pump manifold which can be hard to see. Get a flashlight and give the pump a very close visual inspection to see if there are any cracks in the manifold. If there is do not attempt to fix this with epoxy except as an emergency repair to try to hold until replacement parts / a replacement pump arrives.


Pool Filter Leaks

Pool filters are the most likely item to develop a leak at the threaded pipe connections. If you have a leak on your filter that is not coming from the threaded connections there are a few other things that could be causing it. First and most importantly, if the filter tank itself is leaking be sure to turn off the pool equipment until you have resolved the problem. Filter tanks are large pressure vessels with far more potential energy than most people realize. If a filter tank were to explode, which can happen, with someone standing near it, this would likely be fatal to the person. Extreme caution should be taken around pool filters that are under pressure and you should never attempt to repair a cracked filter tank - replacement is the only option.

Filters can also develop leaks from a few other common locations. The drain plug on a pool filter is often threaded and hard to reach due to its location so this can result in cross-threading of the connection. If this happens the drain cap can leak even once you have threaded it on correctly. Teflon tape can be used to reconnect the drain plug if it is a threaded connection that is leaking. Silicone is not likely to work well since it will be very hard to dry the location completely. Instead use a silicone-like product that is suitable for use in wet locations like Lexel waterproof sealant.

Most commonly pool filters will leak from somewhere up top such as from the pressure gage, sight glass, filter head or backwash line locations - depending on the type of filter that you have. Pressure gage leaks need to be resolved with a new application of thread sealant. The sight glass has an O-ring that can often become lost and this can result in leaks in this location. Replace the O-ring for the sight glass or use teflon tape to thread in the sight glass in a pinch though this may not always solve the problem on its own. If you have a sand filter and you discover, or suspect, that you are losing water out of the backwash line on your filter even though you are not on the backwash setting, this can happen. The spoke gasket inside the filter head can become displaced from back pressure, from debris or from misuse of the filter (such as changing filter settings while the pump is running). You can attempt to open and re-seat the spoke gasket, potentially setting it in place with crazy glue, however there is another solution to this problem also. Since some filters are especially prone to having this problem, a workaround solution is to install a ball valve on your backwash line right where the line exits the filter head. Simply open the valve when you backwash and close when you are finished to prevent water from escaping the system. If you do not have problems with water clarity, and no sand is escaping the filter and ending up in the pool, then this effectively resolves this type of filter leak.



The final leak location for pool filters is from the band clamp. Most filters have a band clamp of some kind, whether a small one for a multiport valve on a sand filter, or a large one like you would find on a cartridge filter, and they can periodically start to leak. If the gasket on the band clamp is dry this can cause the leak and applying a silicone based lubricant will help to resolve. In stubborn leak cases then use a rubber mallet to tap the band clamp firmly all the way around the filter before tightening the clamp further. Care must be used as tightening this clamp too much could potentially break the filter flange since it is only plastic.


Pool Heater Leaks

There are not many ways that pool heaters will leak that can be repaired easily by a pool owner. Most commonly water leaking from a pool heater is an indication that the internals of the heater have failed, usually due to freeze or chemical damage, and the heater will need extensive service to repair. The most common leak locations on a pool heater other than this are with the draincocks or with the pressure switch inside the heater.

The draincocks are the ports that you can open to drain and winterize your pool heater. Most pool heaters have them with about half of them being plastic and half of them being brass. Plastic drain plugs are just like the ones used for pool pumps and are easy to see if they are leaking and replace. Brass draincocks are a little harder to work with as they can be sometimes stubborn due to cross threading of the draincock. Since the draincock and the heater are made from different metals there will be some corrosion in these areas. If you leave the draincocks out for any length of time the rust that forms may prevent you from achieving a true seal in this location. If yours are already rusted then you will need a thread tap set and chase through the hole to clean the threads before putting the draincock back in. To prevent this you should leave brass draincocks installed year round (remove for winterization and replace right away) as well as using an anti-seize lubricant.

The pressure switch is something that can leak on a pool heater - especially in the spring when you start up the system for the year. The pressure switch is located inside the heater and should be disconnected for the winter season. Being inside the heater it can often be forgotten about until start up when a water leak would be noticed. Pressure switches for pool heaters are expensive and can break very easily so care should be taken when you are working with yours. Try tightening the pressure switch if it has a slow leak which is usually a 7/16" or 1/2" nut size. If the pressure switch is damaged or broken in any way then replacement is your only option. Note that not all pool heaters have pressure switches that require winterizing, such as with Pentair and some Hayward products.


Leak In Pool Skimmer


If you have a leak in your pool skimmer then you have a serious problem on your hands. Most commonly a leaking skimmer will be due to a crack in the body of the skimmer itself. This is usually from improper winterization and freeze damage. The skimmer is one of the most likely components of your pool to fail from improper winterization and repair / replacement options are limited. If you have a crack in the body of your skimmer then this is one of the times that epoxy might be a good option for you. While unlikely to repair the problem permanently this may buy you some time to save up for a more expensive repair.

Vinyl liner pool skimmer leak - If you need to replace the skimmer on your vinyl liner pool then you are probably going to need a new liner. This is one of the reasons that a pool should be inspected thoroughly before installing a new liner. A skimmer failure, coping failure or return flange failure could cause you to need to replace the liner again in order to make the required repairs. Vinyl shrinks as it ages and taking off an existing faceplate will usually result in the liner shifting and you will not be able to line up the original holes in the liner. If your liner still has life in it then you can try to epoxy the skimmer leak which may help you to put off the repair.

Concrete pool skimmer leak - A skimmer leak in a concrete pool can be an expensive repair. As with a vinyl pool if you have a crack in the body of your skimmer you can attempt to epoxy it using a two part underwater epoxy made for swimming pools. If you need to replace the skimmer this can be a big job. Most concrete pools will have a solid concrete box poured around the skimmer to help attach it to the pool wall. Replacing the skimmer involves digging up the skimmer and jack hammering out the concrete. This can often result in damage to the pool coping and the interior surface around the mouth of the skimmer but not always. If you are lucky you can demo the old skimmer, dowel in rebar to the pool wall, install the new skimmer and pour concrete again without damaging the coping and interior surface. This is not likely a do-it-yourself job for most pool owners.



This 2 part pool epoxy would be an example of the kind of epoxy that you would use to try to repair a crack in a skimmer, body, throat or around the mouth if yours is leaking. While not a permanent repair this may buy you time to plan and save for a larger renovation that includes replacing the skimmer. This product will set even underwater so there is no need to drain the pool - just be sure to mix equal parts of each A and B components for the strongest result.

Pool Plumbing Line Leaks


If you have a leak somewhere in your plumbing system, or more likely a suspected leak, it will be very difficult for you to locate and repair this. Since most commonly the pool plumbing lines are buried underground you will need to rely on symptoms of the leak to point you in the right direction. There are not many tests that a pool owner can do to determine the exact location of an underground leak. A swimming pool professional would pressure test the system and use listening devices to locate the leak however even in the hands of a professional with access to the best tools, finding a leak can still be a frustrating experience. This is why there are companies that specialize in only leak detection.

Unexplained water loss is the main symptom of an underground pool plumbing leak. Sinking, cracking or shifting of the pool deck is another sign that water is escaping the pool system somewhere. If the paving stones above one of your pool returns are sinking then there is a good chance this area is currently leaking. The same can be said for the area around the pool skimmer as the connections to the bottom of a skimmer can be difficult to make. This can result in a weak spot that is likely to develop a leak. Also, the skimmer pipes are prone to damage from poor winterization just as the skimmer body is - except that you can not put epoxy on the pipe connection points as they are buried. If you have a serious leak around your pool returns or skimmer connection then you will need to dig down and expose this area to repair it.

In addition to leak detection equipment, many experience pool technicians understand how pools tend to break. With an understanding of the most likely locations for a leak to develop you can increase the chances of finding the leak. For example, when you install a pool return the pipe should 90 bend down right after exiting the pool wall. Having a length of straight pipe in this location, like many pools (improperly) have, will almost certainly result in a leak at some point in the future. The weight of the earth settling around the pipe will pull it down, which given enough length of straight pipe will put too much stress on the top of the return where it meets the pool wall. This is one of the single most common places to have a leak in your pool plumbing system.



A pool does not need to be old in order to develop a leak. Unfortunately many pool installers are not familiar with proper pressure testing procedures - something that should be done at multiple stages for a new pool construction project. It is possible to miss potential leaks during the pressure test if the test is not conducted correctly, or for a long enough period of time. A small leak will develop into a larger leak over time and a plumbing line failure at a random location in the line is the hardest type of leak to diagnose and locate. It should be noted that pressure testing is extremely dangerous and should only ever be attempted by qualified individuals on a closed jobsite to ensure the safety of anyone working in or around the pool area. The pressure test will definitively identify which pipes are leaking and which are not which will allow you to focus in on one location of your pool to identify the leak location.


The most common test that a pool owner will turn to for finding leaks is the dye test. What is important to understand is that a dye test is seldomly conclusive and evaluating the results of a dye test is more difficult than one might believe. A dye test is a very basic test to determine where a pool is leaking however it is better for locating structural leaks as opposed to plumbing line leaks. A crack in your skimmer or a crack in your pool shell would be good examples of where a dye test might be useful. The dye will be pulled into any active leaks that it is in close proximity of. Dye tests are also very useful for around stair flanges for in-wall steps on vinyl liner pools as the flange for this is installed with dozens of screws - any one of which could potentially be causing a leak. For pool plumbing a dye test would only be useful for locating large leaks as shown in this video.




Pool leak dye testing can be done with food coloring or with the phenol red dye that comes in any DPD pool water test kit. The only problem with these is that the dye dissipates very quickly. You can also get a dark color dye as shown with the video above but the best dye to use would be the florescent dye as pictured here. The dye is thick and will stay together in the water well, as well as being highly visible making it easier to see if the dye is being pulled by a leak. Unless you are testing only a single, specific location, then it would be a good idea to order a fluorescent dye refill bottle.





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