Pool & Spa Leaks: FAQ's

How do I know if my pool is leaking?

Filling a pool that has a leak
  • Water level drops 1/4" or more in 24 hours
  • Standing water, mushy spots, or uneven grass growth around pool
  • Abnormally high water bills
  • Automatic filler is always on
  • Abnormally high chemical or salt usage
  • Cracks in pool tile, shell or pool deck
  • Uncontrollable algae
  • Poor suction and/or bad circulation

Automatic Water Fillers

If you have an automatic water filler, or 'autofill', it should be shut off at least twice per year, just to make sure a leak hasn't developed. Leaks that are 'masked' by automatic refill units can go on for years, costing money for wasted water and in the process create serious structural damage.

When a pool that has an autofill begins to leak, often the only indication will be water chemistry that seems chronically unstable or out of balance. Or, in the case of a salt pool system, salt levels that inexplicably keep dropping.

No Cost Self-Test

The best way to truly determine if your pool is leaking, is to perform a Bucket Test. It does not cost anything and can easily be done by the home owner.

How much water is my pool losing?

Water Loss Calculator

For every 1" decrease in water level your pool loses:

To determine how many inches of water your pool or spa is losing, perform a Bucket Test. Surface area in square feet multiplied by 0.6 equals the gallons of water lost when pool water drops 1 inch.

Where is the water going?

Displays ground around a pool that has been lifted almost 3 inches by a leak

The answer to that question depends on the type of soil you have. Many times, the water simply obeys gravity and goes straight down. This can settle soils, causing soil movement, which includes movement of the structures built on top. In the picture to the left, the ground around a pool was lifted almost 3 inches by a leak.

In southern California there is a lot of clay in the soil. Clay has varying degrees of expansion potential. This means that when clay absorbs water from a leak in the pool, it will actually swell and expand its total volume. This can lift and crack even the heaviest steel reinforced concrete slabs, either under the house or around the pool. It can also exert lateral pressure on pool walls, causing the pool shell to crack. Repairing this type of damage can be expensive. It is always the best option to FIND THE LEAK AND STOP THE WATER!

How do we find the leak?

The swimming pool is viewed in basically three aspects:

  1. Underground Plumbing Network
  2. Structure or Shell
  3. Aboveground Plumbing and Equipment(pumps, filters, etc)

Underground Plumbing Network

Picture of Pool with Leak found under a few tiles

The underground plumbing network is pressure tested using a method that is extremely sensitive. If a section of piping indicates a leak, an air/water mixture is induced in the pipe. Operator experience comes into play here since the air/water mixture must be fine tuned to achieve the correct vibration, which is subsequently picked up by the sonar/ ultrasound unit. No two leaks are exactly the same. Soil conditions, size and length of pipe, depth of leak, and many other factors, have a bearing on interpreting the signals coming from underground. The sonar technician has to develop a mental 'catalog' of sounds over years of experience, and compare these with what he is hearing from underground. Sonar signals can echo, or be louder in an area where the soil is different, or can follow a path of least resistance. The sonar tech has to mentally work through all these challenges to achieve an accurate location.


A single tile removed to repair pool leak

The importance of accuracy is illustrated by a broken pipe under a brand new, custom deck in La Jolla California. After many months of construction and remodeling, the homeowner was extremely upset when she was told by her pool service person that the pool was leaking. She had visions of another long, costly, invasive process to remedy the problem. Leak Technologies was called in and did a comprehensive leak test on the pool. It was determined that the main re-circulation return-line for the pool was broken and leaking under the deck. As you can see by the picture to the right, our sonar locate was extremely accurate, allowing the entire repair to be performed by removing and replacing only one single tile! To achieve this degree of accuracy, state of the art equipment must be combined with operator experience.

Structure or Shell

The shell, or structure of the pool, is tested underwater using pinpoint dye testing methods. The leak detector checks areas like the main drain, the underwater light niche and conduit, etc. He looks for plaster fatigue around pipes, or any area that is a potential 'exit point' for the water. This aspect of testing requires intense focus on detail so as not to miss even the smallest opening. A crack small enough that it would be unseen from topside, can account for the loss of many gallons of water daily.

Aboveground Plumbing & Equipment

The aboveground plumbing and equipment is also a very important aspect of a comprehensive leak test. Certain plumbing configurations can allow water to exit the internal plumbing system without the homeowner being aware. All these areas must be carefully scrutinized.