The Bucket Test
Use The Bucket Test to determine whether or not you have a leak in your pool.
How to Perform the Bucket Test
Have your pool filled to its standard operating level (middle of skimmer throat). Using a 5 gallon bucket, fill it approximately 1-2 inches from the top of the bucket.
Make sure the pump is off when setting the bucket as well as when checking the bucket results. Also make sure the pump runs its normal cycle after the bucket is set. Immerse the bucket in the pool to about 5 inches. Setting it on the first or second step of your pool should suffice.
Mark the water level inside the bucket and the water level outside the bucket (masking tape works well).
If your pool has an autofill make sure to shut off the autofill and discontinue use of the pool until the test is completed.
Come back in 24 hours to compare the inside water level to the outside water level. If the water level outside the bucket has dropped more than the water level inside the bucket, you likely have a pool leak and need to call a professional. If the water inside the bucket drops more than the pool than it’s possible your pet drank the water.
Make a note to check the bucket at exactly the 24 hour mark, as waiting longer than this can give inaccurate results as the pool has a larger surface area than the bucket and will evaporate at a faster rate than the bucket. If it rains you will have to wait and start over when there is a clear forecast.