Among swimming pool connoisseurs, a concrete pool is considered the gold standard. With its size and shape limited only by imagination and budget, and its average useful life of 50 years, a concrete pool has numerous advantages. However, even the best isn’t immune to developing a leak. In this situation, knowing the tell-tale signs can help prevent additional damage – as well as the expense of a more extensive repair and continued high water bills.
Where Can a Concrete Pool Develop Leaks?
There are three main types of leaks that can occur in a concrete pool. According to Jason Hughes of River Pools, these are the areas to keep an eye out for:
Structural leaks – Any leak in the structure of the vessel itself is known as a structural leak. In most cases, it means there is a crack or fissure in the pool shell. Structural cracks can occur due to poor construction or engineering, ground movement, settling due to shifting soil, and groundwater pressure. It is crucial to understand that a structural leak needs to be repaired immediately.
Fitting leaks – Any fixture that penetrates the pool shell is a fitting. For example, pool lights, skimmers and pool jets are fittings that can develop a leak over time. When pool contractors insert these fittings into the pool shell, they pack them with plaster, making these spots vulnerable to leaks. Our blog post – “What to Do About a Leaking Pool Skimmer” – covers this type of leak in detail.
Plumbing leaks – Correct installation during the construction stage is critical because if the plumbing moves at all, it can leak. This means that the plumbing needs to be secured during installation. If it’s held down with straps or run all the way to the ground, the plumbing will not move. However, settling in the ground can cause systems to move, creating a leak in the plumbing. Corrosion is another issue that may cause a swimming pool’s plumbing system to leak.
How to Identify a Pool Leak
Now that you’re being observant, Hughes lists the following red flags to look for:
- Cracks in the concrete vessel.
- Loose or displaced tiles.
- Settling of the concrete vessel into the ground.
- Wet spots or standing water around the pool.
- Adding more than usual water to your pool.
- An increased water and electricity bill.
- Algae formation, especially after a chemical treatment.
- The automatic filler releases water constantly.
Should you suspect a leak but want confirmation before calling us to locate it, our blog post – “Five Ways to Detect a Pool Leak” – provides two tried-and-true methods: the bucket test and the food color test. Better yet, both are free or very inexpensive, if you don’t happen to have a bucket, painter’s tape or food coloring on hand.
Bucket test – This test requires a 5-gallon bucket and a marker or painter’s tape. Turn off the system for at least 24 hours. This test is creating two surface areas of water to test the level of the water itself.
- Fill the bucket up to 3-inches from the top.
- Set the bucket on the second step if possible, making sure the water level is higher inside the bucket. This helps prevent the bucket from floating in the pool.
- Make a mark both inside and outside the bucket to indicate each water level. Make sure the pump is turned off for the measurement.
- Wait 24 hours to measure the change in water level for both marks.
If each level measures the same amount of change, you do not have a leak. If the difference on the outside of the bucket in the pool is greater than the inside of the bucket, you do have a leak. This indicates that your pool has lost more water through leaking than by the natural occurrence of evaporation.
Food color test – While the bucket test indicates that your pool has a leak, the food color test helps you locate the possible source. First, turn off the pool pump and skimmer. Take a small squeeze bottle and fill it up with water. Next, add a few drops of red food coloring to the squeeze bottle. Once the water settles, place a few drops of colored water into the pool. You can start from the steps and check for leaks in the pool. If there is a leak in your pool, you will see the colored water leaving the pool from that area. You can put additional drops of colored water into the pool around areas where you think there might be a leak – such as a skimmer gasket, light fixtures and the drain opening.
The good people at In The Swim provide the following additional concrete pool leak detection tips:
- If your pool leaks when the equipment is on, it indicates a pressure-side return leak. When the filter pump is on, the plumbing on the pressure side (after the pump) is under pressure.
- If your pool leaks when the equipment is off, it indicates a suction-side leak. These are pipes that bring water from the pool. When the filter pump is on, the plumbing on the suction side is under vacuum.
- If there is a constant leak in your pool, it indicates either a plumbing leak or a crack in the pool shell.
- To check for a leak at the equipment pad, look closely at the filter, pump, heater and valves. Check the ground for moisture. Turn the pump on and off looking closely for spraying water when the pump is turned off. A small drip or two will not be the source of the leak. If loss of water level is noticeable in the pool, it won’t be a drip, but more of a trickle.
- To rule out a plumbing leak, shut off the pump and plug all the lines. If your pool keeps losing water, it means there is a leak somewhere else (there could also be a leak in the plumbing). If the pool stops leaking, remove the plugs one-by-one to locate the leak.
- If there is a traditional perimeter tile band at the waterline of your pool, there could be a leak inside the skimmer, or a crack in the tile.
What Happens If You Ignore a Pool Leak?
Nothing good happens if you avoid the situation and ignore the signs of a leak. You may not want to investigate for fear of having to spend money for detection and repair, but you can be assured that a pool leak will only get worse and more expensive to repair – as well as cause additional structural damage. Pool and spa builder Swimming Pool Steve offers the following account of what you can expect should you shirk your responsibility.
“As water escapes your pool system it can start to accumulate in areas where it should not be. Chlorinated water, when allowed to escape the pool, will begin to damage metal components within the pool structure such as galvanized steel walls of vinyl liner pools, and rebar embedded within the shell of concrete pools. In addition to the concern of chemical damage, an even greater concern is the movement of water through the ground around the pool. Slow moving water can carve right through solid rock … if given enough time.
“Water traveling through the ground around your pool will strip the cement from concrete, leaving only sand and gravel behind. Over a long period of time enough cement has washed away from the concrete to reduce the strength drastically. Where once there was a lattice network of cement binder along with sand and gravel aggregate, only sandy gravel remains.”
Swimming Pool Steve leaves this parting observation:
“Over a lifetime of swimming pool contracting, and being someone who specialized in difficult remediation projects, the worst pools that I ever had to fix were ones that had been leaking for an extended period of time. Swimming pools are built to last, but the specific type of damage that underground leaks do is pretty much a worst case scenario. No matter what type of swimming pool you have, vinyl liner, concrete or fiberglass, the last kind of problem that you want to have is a structural failure. Underground leaks that are left for an extended period of time will almost always cause problems for the pool structure. No pool is built to have an active leak and having one compromises the efficiency of the pool in the short term, combined with longevity of the installation in the long term.”
Enjoy Your Concrete Pool for Years to Come
Being proactive in keeping your concrete pool in good repair can go a long way in preventing leaks. Our blog post – “Concrete Pool Maintenance – What You Need to Know” – provides valuable information and advice. However, calling our experienced team at Certified Leak Detection if you suspect a leak will help keep a bad situation from becoming much worse.
We use technology and techniques we have developed over 20 years in business. In addition to quick detection of pool leaks, we provide industry-leading leak detection for spas and hot tubs, as well as slabs and foundations. Serving areas throughout Central Florida – including Orlando, Longwood, Lake Mary, Sanford, Kissimmee, Clermont and Winter Springs – our team is ready to answer your call. Contact us for quick, reliable service!