Why Is My Swimming Pool Losing Water?
9 Causes Cape Town Pool Owners Should Check
A swimming pool will naturally lose some water.
Hot weather, wind and evaporation can cause the water level to drop, particularly during Cape Town’s warmer and drier periods.
But if you’re constantly topping up your pool and the water level keeps falling, you may have a swimming pool leak.
The difficult part is knowing whether you’re dealing with normal evaporation or an actual leak.
How Much Water Should a Swimming Pool Normally Lose?
There isn’t one universal amount because evaporation depends on several factors: temperature, wind, humidity, pool surface area, water temperature, exposure to sunlight, whether the pool is covered, and how frequently the pool is used.
That means a small drop in water level doesn’t automatically mean your pool is leaking. However, a noticeable or persistent drop that requires frequent topping up deserves investigation.
9 Reasons Your Swimming Pool May Be Losing Water
1. Normal Evaporation
The simplest explanation is evaporation. Water naturally evaporates from the surface of your pool, particularly when temperatures are high, wind is strong, the pool is uncovered, the water is warm, or the pool receives direct sunlight.
Evaporation is not a pool defect. The question is whether the amount of water you’re losing is reasonable for the conditions.
2. A Leak in the Pool Shell
If the actual pool structure has developed a crack, damaged section or other defect, water can escape from the pool itself. A structural leak may become more noticeable when the pool level drops consistently, water loss increases over time, the pool loses water even when it isn’t being used, there are unexplained wet areas around the pool, or surrounding soil appears unusually damp.
If the pool shell is damaged, simply adding more water doesn’t solve the underlying problem. This is where professional pool leak detection becomes important.
3. Leaking Underground Pipes
This is one of the more difficult problems for a homeowner to diagnose. If one of those pipes develops a leak underground, you may not see water coming directly from the damaged section. Instead, you might notice unexplained water loss, damp ground, soil movement, unusually wet areas, reduced water circulation, or equipment behaving differently.
4. A Leaking Skimmer
The skimmer is an important part of your pool circulation system. If the skimmer or its surrounding connections develop a leak, water can escape even though the rest of the pool appears perfectly normal. Pay particular attention if the water consistently stops dropping around the level of the skimmer.
5. Leaking Pool Fittings
Pool fittings and connections can also develop leaks. These may include return jets, suction fittings, drains, lights, skimmer connections, and plumbing connections. Some leaks are obvious. Others are hidden behind surfaces or connected to underground plumbing.
6. A Leaking Pump or Filter System
Not every pool leak comes from the pool itself. Your equipment area should also be inspected. Check for water around the pump, leaking unions, damaged seals, leaking filter connections, cracked equipment components, water escaping around valves, or unusual dripping.
For equipment-related problems, Ocean Pools also provides pool equipment repair and maintenance services.
7. A Damaged Pool Light
Pool lights are another potential source of water loss. The light fitting penetrates the pool structure, which means damage around the fitting or associated housing can potentially create a leak.
8. A Crack or Damaged Surface
Cracks can occur for different reasons depending on the pool construction, age and surrounding conditions. A crack doesn’t necessarily mean the entire pool needs to be replaced. For some older pools, persistent leaks may also raise the question of pool relining or renovation rather than simply carrying out another temporary repair.
9. Water Loss During Pool Use
Sometimes the “leak” isn’t actually a leak. Swimming, splashing and water features can remove surprisingly large amounts of water from a pool. You should therefore compare water loss on a normal-use day versus a day when the pool is unused.
Pool Leak or Evaporation? Try This Simple Test
One of the easiest ways to investigate unexplained water loss is a bucket test.
- Fill a bucket with pool water.
- Place the bucket on a stable pool step so that the bucket water is exposed to the same environmental conditions as the pool.
- Mark the water level inside the bucket and the pool’s water level.
- Leave both undisturbed for a period of time.
- Compare the reduction in the bucket with the reduction in the pool.
If the pool level falls substantially more than the bucket level, that can indicate that water is escaping from somewhere other than normal evaporation.
Pool Losing Water Overnight? Pay Attention.
One particularly important warning sign is: Your pool loses noticeable water overnight when nobody is using it.
If there is no swimming, splashing or other obvious explanation and the water level continues falling, investigate it.
What Happens If You Ignore a Pool Leak?
A small leak may initially seem like an inconvenience. But persistent water loss can create several problems:
- Increased water consumption
- Chemical imbalance
- Equipment problems
- Surrounding property damage
- More expensive repairs
The right response isn’t panic. It’s early diagnosis.
Can a Leaking Pool Be Repaired?
| Problem | Potential solution |
|---|---|
| Leaking fitting | Repair/replacement |
| Damaged pipe | Plumbing repair |
| Equipment leak | Equipment repair |
| Significant surface deterioration | Relining/resurfacing |
| Older deteriorated pool | Renovation or relining |
Should You Repair, Reline or Replace the Pool?
This is where the problem becomes a bigger investment decision. You have several options:
- Option 1 — Repair: Best when the underlying pool remains structurally sound.
- Option 2 — Reline or Resurface: Potentially appropriate when the pool’s surface has deteriorated. Pool Relining in Cape Town →
- Option 3 — Renovate: May make sense where several components need upgrading.
- Option 4 — Replace: For severely compromised pools, a new installation may ultimately make more financial sense. See our Swimming Pool Installation Cost in Cape Town: 2026 Price Guide.
Need help with a leaking swimming pool?
Ocean Pools Group provides pool leak detection, repairs, relining and renovation services in Cape Town.
Frequently Asked Questions
Common causes include evaporation, splashing, leaking pipes, damaged fittings, equipment leaks, cracks and structural problems.
Monitor the water level and compare it with expected evaporation. A bucket test can provide an initial indication. Persistent excessive water loss may require professional leak detection.
Yes, depending on the source. Repairs may involve plumbing, fittings, equipment, structural repairs, relining or renovation.
Final Takeaway
If your swimming pool is losing water, don’t immediately assume you need a new pool.
Start by determining whether you’re dealing with evaporation → usage → equipment → plumbing → fittings → structural leakage.
The sooner the actual cause is identified, the easier it becomes to decide whether the right solution is a simple repair, leak detection, relining, renovation or, eventually, a complete replacement.