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Hydrostatic Valves For Swimming Pools

Note: This post may contain affiliate links. This means that at no cost to you, we may receive a small commission for made purchases.

The hydrostatic valve tends to be placed at the deepest end of the swimming pool.

A standard residential pool holds around 20,000 gallons of water, and can produce 150,000 pounds of force, but this changes when the swimming pool is empty. 

The valve is an important piece of equipment on swimming pools, ensuring that there isn’t a build up of groundwater underneath the swimming pool, creating too much pressure against the bottom. 

In the worst case scenario, this growth in pressure can damage the lower layers of the swimming pool, or raise it out of the ground entirely if not properly relieved. 

How To Avoid A “Popped Pool”

There are several measures that can be taken to alleviate the risk of rupturing the bottom of the pool, or indeed “popping” it from the ground. 

1) The first piece of advice is not to drain the pool after heavy rains.

This of course relates to outdoor pools primarily, where excess rainwater can flood the underpool drainage. 

Also, pools set into grassy areas can be made more unstable when the soil is wet from heavy rains, meaning it can become dislodged more easily by the pressure, when the counterpressure from the full pool is removed. 

2) Secondly, another good way to drain an outdoor pool is by pumping the water far away from the pool itself. 

Directing the water away, either into a storm drain, or downhill away from the pool, should alleviate the risk of water seeping into the ground beneath the swimming pool. 

3) Thirdly, you could try removing the hydrostatic pressure relief plugs. 

Simply put, these plugs are responsible for releasing pressure from the pipes underneath the pool. 

You may not need to remove all of them, but releasing a couple should alleviate the pressure significantly enough to avoid any unwanted damage. 

4) One of the most important points to takeaway is not to leave an in-ground pool empty (see also ‘How Long Can You Leave Your Pool Empty?‘) for too long. 

With the risk of excess hydrostatic pressure, there is also the risk of the plaster and vinyl pool liners (see also ‘How To Easily Patch Any Vinyl Pool Liner‘) becoming damaged from exposure to too much of the sun’s heat. 

The best way is to work quickly and efficiently, not draining the pool until you are ready for the work to begin (or as close as possible), and ensure you have the correct tools and equipment ready at hand. 

You could also hire a trained technician to handle the procedure. This will mean that they are more than likely quicker during the process, and have a greater know how of the risks involved. 

Hydrostatic Valves For Swimming Pools

This is also a good idea, because in some cases, draining a swimming pool on your own can void your warranty, leaving you unprotected in the event of unexpected damages down the line. 

Be warned however, these technicians come at an extra cost. 

When To Use Hydrostatic Valves

Hydrostatic valves are usually used when the swimming pool is empty, and there isn’t the same weight pushing down to counteract the pressure of the groundwater beneath the pool. 

The valve merely adds another level of defense, making sure nothing detrimental happens during the draining and refilling process. 

How To Know Your Valve Is Leaking

The main way to tell if the valve has a leak is often obvious. You may notice that the valve cannot close properly, making it incapable of forming a watertight seal, causing a leak. 

This is not always noticeable, as the clarity of water makes it hard to tell.

The best way to tell is to swim down to the bottom of the pool (making sure someone is close at hand with you for safety reasons) and add a few drops of water soluble dye (or food coloring) into the water around the grate, and see if the water is pulled into the drain. 

If the color drains away, then the seal is firm enough and the system is working correctly, but if it doesn’t, or there seems to be sufficient delay in the process, then you may be experiencing problems. 

Identifying Leaks

Of course, the hydrostatic valve is not the only system that can cause leakage when faulty.

A pool is a complex system that is constantly exposed to water and the elements, meaning that wear and tear can happen all the time. 

Typical reasons also include mechanical failure, structural damage, plumbing, broken pipes, and loose, perished, or broken fittings. 

Mechanical Failure

Mechanical failure can come in many forms. 

Firstly, the pump can be faulty, meaning that the water is not being filtered correctly, and mildew and algae can start to form. 

This is also true if you imbalance chemicals, or the pool has an automatic refill option that malfunctions. 

Structural Damage

Structural leaks can occur anywhere in the pool. Fiberglass models can become warped by excess inward pressure, and concrete fittings can be damaged or compromised due to excess water damage, pressure build-up, or poor installation. 

Anywhere there is a crack or seal, there can be a potential leak.

This is why it is oh so important to make sure every seam or connecting components beneath the water level are sealed firmly, especially around underwater lights, and adjoined components such as ladders and water returns. 


Hydrostatic Valves For Swimming Pools

Plumbing issues can be as simple and commonplace as corrosion. When materials are exposed to continuous water flow, they can become rusty or clogged with excess grime, oil, or waste materials. 

Similarly, improperly balancing chemicals can lead improper filtration and water pH, leading to build-ups over time. 

The complex piping system means that broken pipes can occur all the time, making them one of the leading causes of unexplained leaks. 

Return pipes that have settled in the ground at a different level to the pool itself can be a hotbed for cracks and leaks. 

Similarly, the main drain can be prone to leaks around the fixture. Being notoriously difficult to inspect (due to the complex makeup and presence of water) it can be hard to tell if a leak is present. 

Rocks or debris can also become lodged or clogged in the main valve, leading to improper seal, and ultimately a leak. 

The main culprit can often be the skimmer pipe. This is the first line of defense for keeping a pool free of debris and foreign material. As such, it can be very prone to clogs itself. 

Concrete pool skimmers are usually encased in concrete completely, making them extremely difficult to access, especially without high tech specialized equipment, or properly trained technicians. 

Methods of home testing can waste time, money, and water (especially if there is a significant leak), so it is important to hire a professional leak repair firm when tackling a problem that you know is beyond your skill level. 

Another prominent source of leaks can be the equalizer line. Especially common in older pools, this is the non-pressurized pipe that connects the main drain to the underside of the skimmer pipe. 

Due to its difficult to reach position, and the fact that they are usually left out of most pool renovations, means that serious problems can occur all because of some outdated and faulty equipment. 

Loose/Broken/Perished Fittings

As we have mentioned, leaks are most common where there are joins or seams in the system.

Any external fitting, like lights or ladder stems, can be potential victims of perishing (especially rubber seals), or becoming loose and ill fitting due to excess use and wear. 

These should always be the first port of call, but consult an expert before attempting to repair pool lights

Telltale Signs Of Leaks

The obvious sign of a leak would be a significant change in water level. While evaporation does occur in hot climates, this shouldn’t be noticeable to the observer. A leak however, would cause the levels to drop substantially.

Hydrostatic Valves For Swimming Pools

The second sign would be wet spots in the yard, where the underground water has increased in pressure, causing rising damp, or indeed burst pipes underground. 

Thirdly, noticeable rises in water bills should also be a prominent sign. This is of course only if there is no other obvious reason for the increase. 

Fourthly, damaged or moving fittings should be a clear sign. Loose or damaged tiles, corroding pipes, or the appearance of algae are all signs that something is amiss, so it is important to conduct regular checks and be vigilant when using the pool. 

How To Install A Hydrostatic Valve

Step One

The first step is to drain the swimming pool. This is done using the main valve, and can be a lengthy process consisting of several hours or even more than a day. 

Step Two

The next step is to assess where the main drainage pipe is located, disassemble the main drainage grate, and remove the dress ring.

You can remove the drain using a simple screwdriver, or anything else capable of prizing open the fitting. 

Step Three

Next, take the hydrostatic valve and place it onto the valve stem. This is generally composed of a “male” threaded end that connects into the opening of the valve stem.

This should then be tightened to create a firm seal, but this can be done by hand. 

Step Four

The fourth and final stage is to reattach the dress ring, as well as the drain grating, before securing in place once more. 

Once this has been done, the swimming pool can once again be filled ready for use. 

Final Thoughts

And there we have it, everything you should know about the potential problems of swimming pool maintenance, and the importance of the hydrostatic valve. 

The most important piece of information you could take on is to always contact a professional when undertaking major work or maintenance.

This can be much safer, time effective, and even cheaper, depending on the level of damage that could have been inflicted. 

It is certainly better not to take chances where pool maintenance is concerned.

After all, they can be expensive to buy and run, and the continued enjoyment is paramount. 

Remember folks, always be sensible!

author avatar
Anthony Barnes
Anthony Barnes is the founder of Water Heater Hub and a second-generation plumber by profession. Before developing Water Heater Hub, Anthony Barnes was a full-time plumber, and he has undertaken a wide variety of projects over the decades. As a second-generation plumber, it was easy for Anthony to get used to the technicalities of all from a tender age


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Note: This post may contain affiliate links. This means that at no cost to you, we may receive a small commission for made purchases. When it comes to dealing with clogged drains, many homeowners turn