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How to Perform an Evaporation Bucket Test

In the last blog, we highlighted steps swimming pool and hot tub owners can take to help conserve water. Read our past blog by clicking the button below. One of the tips is to check for leaks, but what is the best way to determine if your swimming pool leaks without paying hundreds of dollars for a professional leak analysis? Perform what is known as the "evaporation bucket test." Follow the instructions below to perform the test.


Evaporation Bucket Test Process

According to APSP, average water loss will occur from evaporation due to wind and heat. If the pool loses more than ¼ inch of water a day, there may be a leak. This test will best determine if a pool or spa leaks.

BEFORE starting this test, turn the pool off – the test will take approximately 24 hours, and the swimming pool or spa must remain off and closed to bathers for the entire test timeframe. The test should not be done on a day with high or gusting winds or heavy rains.

  1. Reset pool or spa water level to normal operating level (halfway up skimmer)

  2. Turn off any automatic fill devices and pool cleaner.

  3. REMOVE POOL OR SPA COVER UNTIL AFTER THE TEST IS COMPLETE. Low water levels can cause the cover to collapse and cause damage to the track and pool structure.



  6. Use a 2½–5-gallon plastic bucket or equivalent.

  7. Fill the bucket to about 1 inch below the top with pool water so the wind effect will be similar in the bucket compared to the pool.

  8. Set the bucket on the first or second step or bench so that at least 2/3 of the bucket is submerged in the pool water. Put bricks under the bucket if necessary to raise the top above pool level. The water in the bucket should be a little higher than the pool level; if the bucket floats, put in some bricks or stones to weigh it down. Positioning the bucket like this keeps the bucket water and pool water temperature the same. Place deck furniture next to the steps so no one will move the bucket. Also, to prevent an animal from drinking the water out of the bucket. Put the bucket on the deck near the pool if a step is unavailable. This will affect the evaporation rate because the temperature of the water in the bucket will become the same as the air temperature***

  9. Mark the starting water level in both the pool or spa and bucket. Use a tape or mark that will not harm the pool, spa liner, or surface. Mark the static pool water level inside the skimmer with a scratch mark or piece of tape.

  10. Allow the pool to sit for approximately 24 hours after the start of the test, and re-measure the two water level distances as compared to the first measurements to see if there is a difference in the water loss levels between the pool and the bucket. Any measurable difference (if pool loss is more significant than bucket loss) would indicate a leak.

  11. Quantify the results, write them down, and provide them to your technician with Nirvana Pool and Spa.


  • Generally, the rain will fall in the pool and the bucket equally. However, a pool with flat coping may get additional rainwater pouring off the deck in heavy rain, which would invalidate the test.

  • There will be negligible evaporation if a pool has a solid automatic cover over the pool for the test duration. If you do a bucket test, it will show how much water is being saved by using the automatic cover. Automatic covers must have an automatic pool cover pump on top of the cover and plugged in, ready to function. Otherwise, heavy rainfall could put enough weight on top of the cover to displace pool water over the lowered beam and into the cover box or vault.

  • ***If you place the bucket on a deck, allow a difference in evaporative loss of plus or minus 1/16 of an inch to 1/8-inch total.


Instructions are provided by the Hot Tub and Pool Alliance

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