How to assess watershape leakage with a bucket test
A plastic bucket may be used as a control to accurately evaluate evaporative loss versus leakage loss in a vessel over a 24-48 hour period.
If a leak is suspected in a watershape, it must be assessed as soon as possible. Watershapes include:
- Pools
- Spas
- Cold plunges
- Water features
- Interactive water play
- Lazy rivers
- Float tanks
- Natural swimming ponds
- Wildlife exhibits
- Lagoons
- Baptismal fonts
- Mikvehs
- Grottos
- Waterslides
Potential problems caused by leaks include:
- Water loss
- Water and chemical expense
- Damage to landscape due to excess water and chemicals
- Erosion
- Loss of soil support
- Undermining
- Washout
- Saturation bearing capacity failure
- Hydrostatic pressure increase against structures
- Settlement and/or differential settlement of structures
Usually, leaks are slow enough that they cannot be readily assessed in a single observation. Simply shutting off the automatic fill device may indicate a loss of water in 24 hours but some of that loss is due to evaporation which needs to be excluded from the loss analysis.
A bucket test utilizes a 5-gallon bucket as a control to assess the amount of evaporation which can be subtracted from the water loss in the vessel to determine the leakage loss.
Simple Bucket Test
This test is for simple watershapes and does not work for water-in-transit systems including vanishing edges, slot-edges, and gutter pools.
- Verify that the weather is clear of precipitation for the next 48 hours.
- Fill the vessel to its normal operating level.
- Shut-off automatic fill devices.
- Close the watershape so that users, including pets, are not affecting the water volume due to absorption, adsorption, consumption, splashing, excess evaporation due to agitation, etc.
- Use a clean, leak-free 5-gallon bucket. Partially submerge the bucket to fill it between 2 and 3 inches from the top and place the bucket on the top step or a sun-shelf or similar location. If the water is higher in the bucket then there is a risk of water blowing out and affecting the results. If the water is lower in the bucket then the rim of the bucket will limit wind velocities and the bucket will not represent the same evaporation as the vessel. If the bucket is not in the vessel's water then the temperature might change and this will affect the evaporation rate in the bucket relative to the vessel.
- Use tape or a Sharpie to mark the water level inside the bucket and the vessel's water surface outside the bucket. Alternatively, take accurate measurements from the bucket's rim down to each surface. If you plan to repeat this test many times at different locations then consider dedicating a new bucket with permanent self-adhesive tape measure labels on both interior and exterior surfaces.
- Record the date, time and measurements - preferably with digital photos.
- Wait 24-48 hours.
- Record the date, time and measurements again. Determine the water level drop inside the bucket and at the vessel's water surface.
Bucket Test Results
- The water level drop inside the bucket represents pure evaporation since there are no leaks in the bucket.
- If the water level drop inside the bucket matches the water level drop at the vessel's water surface, then no leaks were detected and the water level drop in the vessel was due to evaporation only.
- If the water level drop inside the bucket is more than the water level drop at the vessel's water surface, then either 1) the bucket has a leak or 2) water was added to the vessel through the automatic fill device or other means.
- If the water level in the vessel dropped more than in the bucket, then subtract the bucket's drop from the vessel's drop to determine the amount lost to leakage. For example, if the bucket dropped 7/16-inch in 43 hours and the vessel dropped 13/16-inch, then the difference is 6/16 or 3/8-inch due to leakage.
- To determine the water loss in one day, multiply the leakage amount by 24 hours/test duration. In this example the daily loss would be 3/8-inch * 24 hours / 43 hours = 0.21-inch/day.
- To determine the volume lost in one day, multiple the daily loss by the surface area of the vessel. In this example, 0.21-inch/day * (1-ft / 12-in) * (1,100 ft2) * (7.48 gal/ft3) = 144 gal/day.