Pool Losing Water? Leak vs Evaporation Test | Leakbusters

Here at Leakbusters Lanzarote, our team of leak detection specialists shares their expertise.

The Question Every Pool Owner Asks

Watching your pool water level drop can trigger immediate concern. Is water escaping through a crack somewhere, or is the Lanzarote sun simply doing its work? The distinction matters enormously — one requires immediate professional attention while the other is simply a fact of island life.

After years of investigating pools across the island, I've developed a systematic approach that any owner can follow before deciding whether to call for help.

Evaporation Realities in Our Climate

Lanzarote's geographical position creates a perfect storm for evaporative water loss. We sit within the Saharan air mass path, experience persistent trade winds, and enjoy over 300 days of sunshine annually.

Quantifying Normal Loss

Based on local observations across hundreds of pools, expect these rates:

Peak summer (July-August): 6-8mm daily loss. A standard 8x4 metre pool loses 190-250 litres every 24 hours. Weekly, that's 1,300-1,750 litres or approximately 1.5 cubic metres.

Shoulder seasons (May-June, September-October): 4-6mm daily. The reduction comes from lower temperatures and occasionally increased humidity.

Winter months (November-March): 2-4mm daily. Cooler air temperatures and shorter days slow evaporation significantly.

Windy conditions: Add 20-30% to any seasonal baseline. The alisios wind accelerates surface evaporation dramatically.

Variables Affecting Your Pool Specifically

Several factors influence individual pool evaporation:

Exposure: A pool sheltered by walls or buildings loses less than one exposed to wind from multiple directions.

Surface area: Water features, infinity edges, and beach entries increase evaporative surface.

Temperature differential: Heated pools lose water faster than unheated ones due to the increased vapour pressure at the water surface.

Surrounding surfaces: Light-coloured decking reflects heat back into the pool, marginally increasing water temperature and evaporation.

The Definitive Comparison Method

The bucket test removes guesswork by creating a controlled comparison between your pool and an evaporation baseline.

Equipment Needed

One sturdy plastic bucket (15-20 litre capacity works well)

Waterproof tape or permanent marker

Patience to avoid using the pool for 48 hours

Execution

Step one: Fill the bucket approximately two-thirds with pool water. Place it on the first or second pool step so it's partially submerged but stable.

Step two: Mark the water level inside the bucket precisely. Use tape with a written line or a permanent marker.

Step three: Mark the pool water level on the outside of the bucket at the exact same height.

Step four: Disable any automatic fill devices. Turn off the pump to eliminate variables, though some prefer testing with it running to check for pressure-side losses.

Step five: Wait 48 hours. Avoid swimming or adding any water.

Step six: Measure how far each water level has dropped from its original mark.

Reading Results

Scenario A — Levels match: Both the bucket and pool lost identical amounts. Your water loss is evaporative. Continue normal operations.

Scenario B — Pool lost more than bucket: The difference represents water escaping your pool through means other than evaporation. A 10mm differential over 48 hours indicates a leak warranting investigation.

Scenario C — Pool lost significantly more: Differences exceeding 20mm strongly suggest a substantial leak requiring prompt professional assessment.

Beyond the Bucket: Secondary Indicators

Physical evidence often accompanies pool leaks:

Around the Pool Deck

Shifting pavers or tiles: Subsurface water undermines supporting materials.

Cracks appearing in coping: Settlement from saturated soil beneath.

Unusually lush vegetation: Plants near the pool thriving while similar ones further away struggle.

Soggy lawn areas: Particularly on the downhill side of the pool.

The Pool Structure Itself

Tile cracking or lifting: Especially around fittings and where different materials meet.

Grout deterioration: White deposits (efflorescence) or missing sections around tile lines.

Fibreglass delamination: Bubbling or soft spots on composite pool surfaces.

Vinyl separation: Wrinkles or pulled sections in liner pools.

Equipment Area Observations

Constantly running pump: The system working harder to maintain pressure.

Air bubbles from returns: Indicating a suction-side breach.

Visible drips or wet patches: Around filter housing, pump connections, or valve assemblies.

Understanding Leak Locations

Pool leaks typically occur in predictable areas:

Structural Failures

Skimmer throats: The connection between the skimmer box and pool shell experiences significant stress from thermal expansion.

Return fittings: Repeated tightening of directional eyeballs can crack surrounding material.

Light niches: The sealed housing around underwater lights deteriorates with age and UV exposure on accessible seals.

Main drains: Settlement can stress the connection between the drain and pool floor.

Plumbing Failures

Underground pipework: PVC joints installed during construction can separate from ground movement or improper initial bonding.

Equipment pad connections: Vibration from pump operation stresses threaded and glued joints.

Check valve failures: When backflow prevention devices fail, they can allow water to drain from the system.

Financial Implications of Delay

Pool leaks rarely improve without intervention. Consider the accumulating costs:

Water replacement: At current Lanzarote rates, constantly replacing lost water adds €30-60 monthly to bills.

Chemical waste: Chlorine, acid, and other treatments disappear with escaping water.

Equipment strain: Pumps working harder to compensate for pressure loss consume more electricity and wear faster.

Structural progression: Small cracks become large cracks. Undermined decking requires replacement rather than repair.

Property damage: Water migrating through soil can affect building foundations, retaining walls, and neighbouring properties.

Taking Appropriate Action

For confirmed leaks, professional detection offers significant advantages over excavation-based searching:

Pressure testing reveals plumbing line integrity without opening trenches.

Acoustic equipment pinpoints the escape location by detecting the sound water makes passing through breaks.

Dye testing confirms shell and fitting leaks by introducing visible tracers that follow water paths.

Thermal imaging identifies temperature differentials that indicate water movement beneath surfaces.

Accurate location means targeted repair rather than exploratory demolition — preserving your investment and minimizing disruption.

Maintaining Perspective

Some evaporative loss is simply the price of pool ownership in our climate. The bucket test gives you factual data to distinguish between normal loss and genuine problems.

When results indicate a leak, early intervention protects both your property and your finances. When they confirm evaporation, you can proceed with confidence that your pool structure remains sound.