If your pool is losing water, the first question is simple: is it normal evaporation, or do you have a leak? Some water loss is expected, especially in hot, windy weather, but if the pool level keeps dropping faster than expected, you may be dealing with a structural, plumbing, or equipment-related problem. The U.S. EPA advises pool owners to use an evaporation bucket test to check for leaks, and water agencies such as the City of Mesa recommend comparing pool water loss against a bucket to tell normal evaporation from a real leak.
At 100% Plumbing, we help pool owners identify whether water loss is seasonal and manageable or a sign that repair work is needed. If the issue turns out to be more than normal evaporation, the most relevant next step is usually a professional inspection of your pool leak detection setup or wider swimming pools repairs needs.
How much pool evaporation is normal?
All pools lose some water naturally. Evaporation increases with heat, sun exposure, wind, low humidity, and water movement. The EPA notes that evaporation is a normal source of pool water loss and specifically recommends checking suspected losses with a bucket test rather than assuming every drop means a leak.
That means a falling water level is not automatically a fault. However, when the drop is consistent, unusually fast, or continues even when conditions are mild, it becomes much more important to rule out a leak.
How to tell evaporation from a leak
The simplest way to check is the bucket test.
Place a bucket on a pool step, fill it so the water inside the bucket matches the pool water level outside, mark both levels, and compare them after 24 to 72 hours. The EPA recommends doing this on a day without heavy wind or rain and with automatic fill systems turned off. If the pool water drops more than the water inside the bucket, that points to a likely leak rather than evaporation alone.
Some guidance also suggests repeating the test with the pump running and then with the pump off. If the pool loses more water when the pump is running, that can indicate a plumbing-side leak rather than evaporation or a shell issue.
Signs your pool may have a leak
A leak is more likely if you notice any of the following:
-
the water level drops faster than the bucket test suggests it should
-
you need to top up the pool more often than usual
-
wet ground appears near the pool, pipes, or equipment area
-
cracks, loose tiles, or damaged joints are visible
-
air enters the system or circulation becomes inconsistent
-
the pool loses more water when the pump is running
These signs often point to more than simple surface evaporation. If you suspect the issue is in the shell or finish, pages such as pool crack repair or grouting may also be relevant.
Common causes of pool leaks
Pool leaks can come from several places. In some cases, the leak is in the structure itself, such as a crack in the shell, movement around fittings, or deterioration in grout or tile lines. In other cases, the problem is in the plumbing, circulation, or connected equipment.
Typical causes include:
-
cracks in the pool shell
-
failed seals around lights, skimmers, or returns
-
pipework leaks
-
damaged grout or tile joints
-
worn fittings or valves
-
equipment-side leaks near pumps or filters
If your water loss is related to visible surface damage, underwater repair or replace pool tile services may be part of the solution.
Risks of ignoring pool water loss
Ignoring ongoing water loss can make the repair more expensive. A real leak does not just waste water. It can also affect the surrounding ground, undermine finishes, increase chemical imbalance, and create more wear on the system if you keep refilling and rebalancing the pool.
The EPA’s pool efficiency guidance recommends checking for leaks periodically because ongoing water loss can increase unnecessary water use and hide larger maintenance issues.
In practical terms, the longer a leak is left untreated, the more likely it is to develop into structural damage, finish deterioration, or hidden plumbing problems.
What you can do first
Before arranging repairs, there are a few sensible checks you can carry out:
-
turn off any automatic filler
-
perform the bucket test
-
check whether the loss changes with the pump on or off
-
inspect around skimmers, lights, returns, and visible joints
-
look for damp ground near the pool or equipment area
If the main issue turns out to be heat, wind, or uncovered water rather than a leak, improving evaporation control may help. That is where pool covers installation can make a practical difference.
How 100% Plumbing can help
If your pool keeps losing water and the cause is not obvious, 100% Plumbing can inspect the pool, assess whether the problem is evaporation or leakage, and recommend the right repair path. Depending on the fault, that may involve pool leak detection, structural swimming pools repairs, or broader support through our pools and plumbing services sections.
If your pool is losing water faster than it should, do not rely on repeated top-ups alone. A simple test today can help you catch a small issue before it becomes a costly repair. For expert help with pool leak detection, swimming pools repairs, or a professional inspection, contact 100% Plumbing today.
Frequently asked questions
How do I know if my pool is losing water from evaporation or a leak?
The best first step is the bucket test. If the pool water level drops more than the water inside the bucket over the same period, that suggests a leak rather than normal evaporation.
Can a pool lose water naturally in hot weather?
Yes. Heat, wind, sun exposure, and low humidity all increase normal evaporation. The EPA treats evaporation as an expected source of pool water loss and recommends testing before assuming there is a leak.
What does it mean if the pool loses more water when the pump is running?
That can point to a plumbing-side leak. City of Mesa guidance notes that higher loss with the pump running often suggests the plumbing is the source.
Is topping up the pool enough if it keeps losing water?
No. Repeated refilling hides the symptom but does not fix the cause. If the loss is due to a leak, the damage and water waste can continue until the fault is repaired.
When should I call a professional?
You should call a professional if the bucket test points to a leak, the water level keeps dropping quickly, damp ground appears around the pool, or you suspect shell, fitting, or pipework damage.
