A backyard pool is often a place for fun, relaxation, and exercise. But sometimes, pool owners notice something strange: the water level is higher on one side. This problem can appear suddenly or develop slowly over time. It can lead to confusion, worry, and even damage if not handled correctly. Understanding why a pool becomes uneven is important for both safety and enjoyment.
Many people think pools are always perfectly level. In reality, several factors can cause a pool to tilt or the water to appear higher on one side. Some of these are easy to fix, while others need professional help. This article explores all the reasons why a pool may be higher on one side, how to diagnose the problem, and what steps you should take to solve it.
We will also look at the risks, how to prevent this issue, and answer some common questions.
If you own a pool or plan to get one, this guide will help you spot early warning signs, avoid expensive repairs, and keep your pool safe and enjoyable for years.
Understanding Pool Level Issues
Before looking at the causes, it’s important to know what “higher on one side” really means. Water always finds its level. So, if the water looks uneven, the pool structure itself is most likely the problem.
What Does “higher On One Side” Mean?
This phrase describes a situation where the pool seems tilted. One edge might show more water against the tile or skimmer than the opposite side. Sometimes, the pool deck may also appear uneven. There are two main types of pools affected:
- In-ground pools: These are set into the ground, surrounded by soil and concrete.
- Above-ground pools: These sit above the ground, usually with a metal or resin frame.
Both types can develop a noticeable tilt, but the causes and solutions are often different.
Why Is It A Problem?
An uneven pool is more than just an eyesore. Here are the main concerns:
- Structural Stress: A tilted pool puts stress on walls and foundation, leading to cracks or leaks.
- Water Circulation: Uneven pools can have poor water flow, making cleaning and filtration less effective.
- Safety Risks: Swimmers may trip or slip, and diving can be dangerous in shallow spots.
- Equipment Damage: Pumps and skimmers may not work correctly, causing wear and tear.
Even a small tilt can grow worse over time, so it’s important to fix it early.
Common Causes Of A Pool Being Higher On One Side
Several factors can cause a pool to become uneven. Some are natural, while others are the result of poor construction or maintenance.
1. Ground Settlement
Soil movement is one of the most common reasons for a tilted pool. Over time, the ground under your pool can shift. This can happen because:
- The soil was not compacted properly before the pool was built.
- Heavy rain washes soil away.
- Tree roots grow and push the pool.
As the ground settles unevenly, one side of the pool may sink.
2. Poor Installation
If the pool was not installed on a flat, stable base, it may start to lean. This is especially true for:
- Above-ground pools: The base must be perfectly level before the frame is set up.
- In-ground pools: The foundation (often made of gravel, sand, or concrete) must be even and strong.
Mistakes during installation often show up as uneven water levels within the first few months.
3. Erosion
Erosion happens when water carries soil away from under or around the pool. This can be caused by:
- Faulty drainage systems
- Leaking pipes or pool liner
- Heavy rainstorms
When soil is washed away, one side of the pool may lose support and drop.
4. Structural Damage
Cracks, broken tiles, or damage to the pool’s shell can allow water to escape. This water can erode the soil underneath, making the pool tilt. Signs of structural damage include:
- Cracks in the pool floor or walls
- Sudden drops in water level
- Uneven tiles or coping
5. Tree Roots
Large trees near a pool can cause problems in two ways:
- Roots seek out water and may grow under the pool, pushing it up.
- When roots die or are removed, the soil can collapse, creating empty spaces.
Both situations can lead to one side of the pool being higher than the other.
6. Water Table Changes
The water table is the level underground where soil is saturated with water. If the water table rises, it can push up on the pool, especially if the pool is empty or partially drained. This is more common in areas with:
- High rainfall
- Poor drainage
- Clay soil
A changing water table can make a pool “float” or lift, causing unevenness.
7. Earthquakes And Vibrations
Even small earthquakes or vibrations from nearby construction can cause soil to shift. This can lead to sudden or gradual tilting.
8. Pool Wall Failure
In above-ground pools, the metal or resin wall can buckle or collapse if the base is not level or if the wall is damaged. This can cause one side to appear higher.
9. Improper Backfilling
During in-ground pool installation, soil is put back around the pool (backfilling). If this is done unevenly or with the wrong material, settling can occur.
10. Construction Near The Pool
Adding a patio, driveway, or other heavy structure near the pool can press down on the soil and cause shifting.
Key Insight: Even Small Mistakes During Installation Or Maintenance Can Take Months Or Years To Appear As A Tilted Pool.
Diagnosing The Problem
Finding out why your pool is higher on one side takes careful observation and sometimes professional help.
Visual Inspection
Walk around your pool and look for these signs:
- One side of the pool wall is higher than the other.
- Waterline tiles show more or less water exposure on one side.
- Cracks or gaps in the deck, tiles, or pool shell.
- Sinking or raised spots in the pool deck.
Measure The Difference
You can check the tilt using a simple tool:
- Fill the pool to the normal level.
- Use a tape measure to check the water level at several points around the pool.
- Mark the difference between the highest and lowest sides.
A difference of 1/4 inch (6 mm) or less is normal. More than that may need attention.
Check For Leaks
Look for wet spots, soggy soil, or water loss. Leaks can cause erosion and uneven settling.
Professional Assessment
If you suspect a serious problem, contact a pool contractor or structural engineer. They can use special tools like lasers or transits to measure the tilt and check for hidden issues.
Common Beginner Mistake
Many people assume the pool was always uneven or blame it on a small manufacturing defect. In fact, most problems develop over time, not overnight.
Risks Of Ignoring The Problem
Some pool owners hope the problem will “fix itself” or isn’t serious. This is rarely true. Here’s why you should act:
- Cracks and leaks can become larger, causing expensive damage.
- Equipment may break if water doesn’t flow correctly.
- Safety hazards increase, especially for children and older adults.
- Property value drops if the pool looks or feels unsafe.
- Costs go up if you wait, as repairs become more complicated.
Solutions For An Uneven Pool
Fixing a pool that’s higher on one side depends on the cause, the type of pool, and how severe the tilt is.
For Above-ground Pools
These pools are usually easier and less expensive to correct.
1. Draining And Re-leveling
If the tilt is small, you can:
- Drain the pool (following local laws to avoid fines)
- Take apart the frame and liner
- Level the ground using a long board and a carpenter’s level
- Rebuild the pool
2. Adjusting The Base
Sometimes, only part of the base needs extra sand or soil. Add material in thin layers and compact each one.
3. Wall Or Frame Repair
If the tilt is due to a bent wall, replace or repair the damaged part before refilling.
4. Professional Help
For large tilts or if you’re not comfortable with DIY, hire a professional. They have special tools and know-how.
Practical Tip
Always check the manufacturer’s guide before draining or moving an above-ground pool. Some warranties are void if the pool is moved.
For In-ground Pools
Repairs are more complex and often need experts.
1. Soil Stabilization
If ground settlement is the cause, professionals may inject special materials (like grout or foam) under the pool to lift and support it.
2. Underpinning
This involves adding supports or piers under the pool. It’s common for concrete or gunite pools.
3. Crack Repair
Fix any visible cracks with approved patching materials. For large cracks, hire a pool repair specialist.
4. Deck Leveling
If only the deck is uneven, it might be possible to “mudjack” (inject material under) the deck without touching the pool.
5. Drainage Correction
Fix any drainage problems to prevent further erosion or soil movement.
Key Insight
In-ground pools should never be emptied without consulting a professional, especially in high-water table areas. The pool can “pop out” of the ground.
Comparing Repair Options
Here’s a quick look at different repair methods for in-ground pools:
| Method | Best For | Cost Range (USD) | DIY Possible? |
|---|---|---|---|
| Soil Stabilization | Minor settling | $1,500 – $6,000 | No |
| Underpinning | Major tilt | $5,000 – $20,000+ | No |
| Deck Leveling | Uneven deck only | $500 – $2,500 | Sometimes |
| Crack Repair | Small cracks | $200 – $2,000 | Yes (small jobs) |
Preventing Pool Tilt
Once you fix the problem, you want to make sure it doesn’t return. Prevention is the best way to avoid future headaches.
1. Choose The Right Location
Place the pool away from trees, large roots, and areas with poor drainage. Avoid building near slopes or fill dirt.
2. Prepare The Ground Properly
For both in-ground and above-ground pools:
- Compact the soil before installation.
- Use a stable base of gravel or sand.
- For in-ground pools, ensure proper drainage layers.
3. Install Good Drainage
A well-designed drainage system keeps water away from the pool structure. This prevents erosion and shifting.
4. Regular Maintenance
- Check for leaks, cracks, or wet spots around the pool.
- Inspect the deck and pool structure every season.
- Clean gutters and drains to direct water away.
5. Watch For Warning Signs
Catch problems early by looking for:
- Changes in water level
- Cracks or gaps
- Sinking or raised areas
6. Professional Inspections
Have a pool contractor check your pool every few years, especially if you notice changes.
Comparing Pool Types For Stability
Some pool types are less likely to become uneven. Here’s a comparison:
| Pool Type | Risk of Tilt | Main Weak Point |
|---|---|---|
| Above-Ground | High | Poor base preparation |
| Vinyl In-Ground | Medium | Shrinking soil, leaks |
| Concrete/Gunite | Low to Medium | Soil movement, cracks |
| Fiberglass | Low | Water table changes |
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Real-world Examples
Example 1: Above-ground Pool Sinking
A homeowner in Texas noticed her above-ground pool was about 1. 5 inches lower on one side after a heavy storm. The cause was water runoff eroding the soil under one edge. The solution was to drain the pool, add and compact new soil, and rebuild the frame.
Example 2: In-ground Pool Tilt
In Florida, a concrete pool started tilting after several years of drought, followed by heavy rain. The soil shrank and then rapidly expanded, causing the pool to move. Engineers stabilized the soil with grout injection and repaired cracks to stop further movement.
Example 3: Tree Root Problem
A pool in California developed a bulge on one side. The cause was a large tree root growing under the wall. The tree was removed, the root cut, and the soil replaced. The pool was then stabilized and the deck repaired.
Non-obvious Insight
Sometimes, the pool isn’t the only thing moving. Expanding or shrinking soil can also move patios, fences, or even parts of your house. If you notice changes in other structures, check your pool as well.
The Science Behind Water Level
Some pool owners are surprised by how sensitive pools are to even small changes in the base. Water always seeks its own level, meaning it’s always flat if the container is stable. If water looks uneven, the container (the pool) is not level.
Even a 1-inch tilt in a 20-foot pool creates a visible difference. This is why small shifts in soil can make a big impact.
Calculating The Tilt
To estimate how much your pool has shifted:
- Measure the difference in water level from one side to the other.
- Divide by the pool’s width to get the slope.
A shift of more than 1 inch per 10 feet is usually a sign of trouble.
How Much Is Too Much?
Most experts agree:
- Up to 1/4 inch difference per 10 feet is normal.
- 1/4 to 1 inch may need watching.
- More than 1 inch per 10 feet should be fixed.
What To Do If You Notice A Problem
If you suspect your pool is higher on one side, don’t panic. Here’s a step-by-step guide:
- Stop using the pool until you know it’s safe.
- Measure the tilt as described above.
- Check for leaks or wet spots.
- Inspect for cracks or damage.
- Call a pool professional if you find a problem or the tilt is more than 1/4 inch.
- Follow expert advice on repairs.
- Keep records of all measurements and repairs.
Cost Of Repairs
Fixing a tilted pool can be expensive, but waiting often costs even more. Here’s what you might pay in the U.S.:
- Above-ground pool re-leveling: $500 – $2,000
- Minor soil stabilization: $1,500 – $6,000
- Major pool lifting (underpinning): $5,000 – $20,000+
- Crack repair: $200 – $2,000
Prices depend on your location, the size of the problem, and the type of pool.
Insurance And Warranty
- Homeowners insurance may cover repairs if caused by a covered event (like a storm).
- Pool warranties rarely cover soil movement but may cover installation errors.
Always check your policies and call your agent if you have questions.
When To Replace A Pool
Sometimes, repairs are not enough. You may need to replace your pool if:
- The structure is badly damaged.
- The cost of repair is more than half the cost of a new pool.
- The tilt is greater than 2 inches per 10 feet.
A new pool also gives you a chance to fix other problems, like old plumbing or outdated design.
Expert Advice For Buyers
If you’re buying a home with a pool, always have a professional pool inspection. Ask for a written report on the pool’s level, structure, and equipment. This can save you from expensive surprises later.
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Long-term Maintenance Tips
- Check the water level regularly at several points around the pool.
- Keep trees and large plants away from the pool area.
- Repair small cracks early before they become big problems.
- Clean and inspect drains to prevent water from pooling near the foundation.
- Document all repairs and inspections for future reference.
Comparing Professional Vs. Diy Repairs
| Aspect | DIY | Professional |
|---|---|---|
| Cost | Lower | Higher |
| Skill Needed | High (for major repairs) | Expert |
| Risk | High (mistakes can worsen problem) | Low |
| Time | Longer (especially for in-ground pools) | Faster |
| Warranty | Usually none | Often included |
Credit: jazeswim.com
Additional Resources
For in-depth details on pool construction and soil problems, check out the Wikipedia entry on swimming pools.
Frequently Asked Questions
Why Does My Pool Look Higher On One Side After Heavy Rain?
Heavy rain can wash away soil under part of your pool, causing it to settle unevenly. This is especially common if your yard has poor drainage or slopes toward the pool.
Can I Use My Pool If It’s Not Level?
It’s not safe to use a pool with a noticeable tilt. The water depth may be uneven, and the structure could be stressed or damaged. Fix the problem before swimming.
How Can I Tell If My Pool Has A Serious Tilt?
Measure the water level at several points around the pool. If the difference is more than 1/4 inch per 10 feet of width, call a professional for an inspection.
Will Insurance Cover Repairs For An Uneven Pool?
Coverage depends on your policy. Some types of damage, like from storms, may be covered. Damage from poor installation or soil movement usually isn’t. Always check with your insurance agent.
What Is The Best Way To Prevent My Pool From Becoming Uneven?
Prepare the ground well before installation, use good drainage, keep trees away, and inspect your pool regularly for early signs of problems.
A pool that is higher on one side is more than just a visual annoyance—it can signal deeper issues with your yard, soil, or construction. By understanding the causes, acting quickly, and caring for your pool, you can enjoy safe swimming and avoid costly repairs for years to come.