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Has your pool been steadily losing water since the last wild pool party, or is a whole pool of pool water already forming in front of the pool?

Then you may have a leak in the pool.

Leaks or a pool leak can occur inside the pool or even in the filtration system. Therefore, before you look for the hole only in the pool, you should check the entire filtration system including the pump, pool heater, chlorinator and filter.

With inground pools, such an inspection is not easily possible as a layman, because cracks and breaks in pipes laid underground can also be the cause. It is better to hire a professional, who can best check the pipes for leaks.

Before looking for a possible hole, make sure there is a leak in the first place.

Sunlight causes evaporation, water sloshes out of the pool when you swim and splash, and backwashing the filter also uses water.

Per week, you can expect a loss of water or a need for filling water in the range of 3 to 5%. If you already know your pool has a leak, you can skip this step.

Use the bucket method to determine if there is a leak in the pool

For the bucket method, all you need is a large bucket that should hold about 20 gallons and a black sharpie or thick tape.

Step 1: Experiment setup

Place the empty water bucket on the first or second step in your pool. Now fill the bucket with water until the water level in the bucket equals the water level in the pool. Use sharpie or tape to mark the water level now.

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Note: If heavy rain is announced, you should not perform the test. This is because the rainwater could falsify the results.

Step 2: Turn off the pump/filter system

Turn off the circulation pump and other automated systems to refill the water. Wait for 24 hours.

Step 3: Observation

After a day of waiting, it’s time to check the results. Compare the pool water level to the water level in the bucket. If both the water in the bucket and the pool water have decreased by the same level, evaporation is the cause of water loss in your pool.

If the level of the pool water is significantly lower than the level in the bucket, your pool probably has a leak.

Step 4: Confirm the suspicion.

A one-time observation is not very reliable. Repeat the test to be sure in the cause of the water loss. This time, turn on the pump system.

Step 5: Compare again

If on the second test the water level in the pool is again significantly lower than the level of water in the bucket, your pool probably has a leak.

By significantly, we mean that the difference is at least half an inch. If the difference between the level of the pool and the bucket is more than 0.5 cm, your pool will lose quite a bit of water day after day.

How to find the leak in the pool with the ink method

When it comes to pool maintenance, you need to become self-sufficient. This includes not always hiring a company right away. The vast majority of tasks that pool owners face can be done by you.

With the ink method, you can find the leak in the pool completely without a professional. All you need for this procedure is a pair of diving goggles, a snorkel and dark food coloring.

Step 1: Drain the pool water

Start by draining the water from the pool. Of course, if there is a leak at the bottom of the pool, this is annoying because the water will drain out completely. (See step 3 to learn how to avoid this).

With a leak at the top or in the wall, the pool will eventually stop draining. If the level stops going down, you know the leak must be somewhere around the edge at the level of the current water level.

Step 2: Check the bottom, walls and surrounding area of the pool.

When determining where the leak is, it helps to scan the outside of the pool for wet spots. It is likely that trickles or puddles have already formed.

This is a good way to identify the side where the leak is located. Combine this observation with knowing at what elevation the leak is located.

Keep narrowing the area before using the dye to determine the exact location of the leak. Once you have an idea of where the leak might be, it’s time to put on swimsuits, goggles and snorkel, and head for the water.

Step 3: Use the food coloring to locate the leak.

Move to the area where the leak is suspected to be. Move slowly so as not to stir up the water unnecessarily.

Now spray the dye very close to the pool wall. If the leak is close, a current will form towards the hole. The dye makes this suction visible.

The same scheme applies to the bottom of the pool. With diving goggles on, you can also make currents visible here, with food coloring.

Swim slowly and move only with caution. Any swirls of water will disperse the dye and make the leak harder to find.

With these tips, you can find the pool leak. Now move on to repairing the hole.

Here’s how: Seal a pool leak

If you have a plaster, concrete or fiberglass in-ground pool, you can, in principle, seal the pool leak on your own. However, a professional is more appropriate in this case. The professional help ideally comes from the company that installed the pool at the time. After all, this company knows best how to seal the pool leak.

Sealing a leak in a vinyl pool

Many inflatable pools are lined with vinyl sheeting. It is easier to seal a leak in the plastic. Repair is much easier than with other materials.

Vinyl swimming pools tend to be smaller. That’s a good thing. Because the smaller the pool, the easier it is to find the leak. A leak in a vinyl liner doesn’t mean the entire shell needs to be replaced.

A simple vinyl patch will remedy the situation. This seals the leak and sticks even under water.

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The actual pool patch is quite simple:

  • Such a repair kit includes a large sheet with the vinyl sheet. Cut a large circle out of it. The diameter should be about 5 cm larger than the area to be patched. The circle shape is important because otherwise the patch might come off at the corners.
  • The back of the patch is then covered with the adhesive over the entire surface. (This is already included in the kit).
  • If the leak is over water: Thoroughly clean the area of the leak. Allow the adhesive to dry on the patch for about 2 to 4 minutes, then stick it to the location of the leak. Apply pressure for another 2 to 3 minutes.
  • If the leak is underwater: If the pool leak is underwater, things look different. Apply a slightly thicker layer of the adhesive. Fold the patch in half. Move toward the leak. If possible, the adhesive should not come into contact with water at all. Now open the patch and stick it in one movement to the spot with the leak. Keep the pressure on for 5 minutes.

Tip: Another method is to coat the patch or armor tape with silicone and simply stick it to the hole. 

If the patch comes off again over time, you can apply a new one without any problems. Of course, we hope this doesn’t happen and your pool will last with the patch for all eternity.

Pool loses water while filtering

It doesn’t always have to be that the leak is in the pool. Sometimes the pool loses water while filtering. When this happens, it is usually due to leaking pipes and valves.

Check the multi-way valve and all the seals. Often, something is just stuck or a seal has slipped. Correct the source of the problem and the supposed pool leak should be gone.

Larry has been a true water rat since childhood. Pure pleasure turned into a passion. That's why he is the first point of contact for friends and acquaintances when it comes to pool-related problems. He is an integral part of the PoolHandbook editorial team.