How to Find a Pool Leak

Written by Published in Pool Maintenance

It’s a beautiful Saturday afternoon. Book and tropical beverage in hand, you stroll out to your hand-crafted backyard pool for a well-deserved respite from the week’s woes.

But as your eyes adjust to the harsh light of day, it dawns on you—someone or something has stolen all the water from your pool.

There are plenty of reasons why your pool could be running low on H2O. The most common are natural evaporation (which is why we recommend a pool cover), and splash-out. Splash-out simply means water lost from using the pool, such as exiting or playing. If you have kids, you likely have a lot of splash-out.

But what if you already use a cover and you don’t have kids?

Well, your pool probably has a leak. But to find the leak, you have two options: call a professional, or conduct a few experiments on your own.

While calling in help is faster, there are certainly a few simple tests you can run at home. If you do decide to self-diagnose, remember to run these tests in sequence, one after the other!

(It’ll make sense in a few minutes.)

So without further ado…

The Bucket Test

If you’ve already ruled out evaporation and splash-out, it’s time to grab a bucket. Grab some bricks while you’re at it, or another heavy object to hold that sucker down.

Now, take your bucket and place it on one of the first swimming pool steps where it will be partially submerged. Fill it with a couple bricks to hold it down, and fill the bucket with water to the same level as the pool’s water outside the bucket.

Next, mark both the inside and the outside of the bucket with a marker or some tape just above water level. Now we play the waiting game.

Check back in a day or two. Ideally, we want to see an equal decrease in water level both inside and outside the bucket. That means water is evaporating normally and there probably isn’t a pool leak.

On the flip side, if you see a big drop outside the bucket and little change inside, we need to do some digging and find out where your leak is.

Onwards, to…

The Filter Test

Your pool or spa’s plumbing is a frequent culprit when rooting out leaks, so let’s check here next.

To do that, we need to check your pool’s water level twice—with the filter on and off. We’ll stick with tape this time as our trusty measurement tool, since you probably don’t want to draw all over your pool with a marker.

Again, we’ll need some patience for our experiment to work. After running your pool filter for whatever length of time you normally use—let’s say 8 hours—check the water level. Now, shut off the filter and fill ‘er back up to the line of tape.

Go grab a sandwich and a margarita, take a nap, meditate, then make sure to come back after another 8 hours to check the water level. If your pool lost much more water during the filter run, you’ve probably got a leak somewhere in the plumbing system.

One of the telltale signs of a leaky plumbing system is soggy or eroded ground near your pump and filter, but you might have a plumbing malfunction without any superficial evidence.

Of course, your pool could have lost a ton of water during both 8-hour runs. In that case, you might have breakage in your pool’s shell or liner. Our last stop is…

The Dye Test

It’s usually at this point when I’d recommend pool owners call a professional. You’ll see why in a second, but for true do-it-yourselfers, here’s the game plan.

The dye test requires you to get in your pool and search for cracks. Once you find an abnormality, you have to take a little eye dropper filled with any colored solution (make sure it’s safe for you and your pool), and squirt a few drops near the crack.

One of two things will happen:

  • The dye will disperse and disappear.
  • Or, the dye will be sucked into the crack.

If the second option happens, the dye (and your pool water) must be going somewhere. This process can be incredibly tedious, especially if you have a big pool. But if you have a smaller pool or a whole lot of free time, give it a shot.

I Found the Leak. Now What?

Finding the leak is one thing, but fixing it is another matter entirely. Sadly, we can’t stuff leaky pools with wine corks or bandages like they do in cartoons.

Fixing your pool’s leak still probably requires professional help for a number of reasons. The most important of which is:

What if there’s more than one leak?

Pool pros know all the best and fastest techniques to shore up your pool or spa and stop your back yard from turning into a swamp. They’ll also save you the headache of leaving a running hose in your pool 24/7 in a desperate fight against physics.

If you have a leak (or think you do), give some of these tests a shot. And if you need to call in professional help, don’t hesitate to give us a ring—we’ve plugged more leaks than we can count.

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