Semi-inground pools offer the best of both worlds: they blend the affordability of above-ground pools with the sleek, built-in look of inground designs. But while they’re a great choice for sloped yards and creative landscaping, semi-inground pools come with their own unique set of challenges.
From structural concerns to plumbing issues and water chemistry complications, this guide breaks down the most common semi-inground pool problems—and exactly how to deal with them.
1. Pool Wall Bowing or Shifting
Quick Answer: Wall movement or bowing is often caused by improper backfilling, unstable soil, or water pressure imbalances during installation.
Common Causes:
- Uneven or uncompacted backfill material
- Excess hydrostatic pressure from heavy rain or groundwater
- Insufficient water level inside the pool during backfill
How to Fix:
- Re-excavate and backfill using clean gravel or flowable fill
- Always maintain proper water level while adding soil
- Install a French drain around the perimeter to manage excess groundwater
Pro Tip: Consult with a pool contractor if structural shifting is significant—reinforcement may be needed.
2. Liner Wrinkles or Slipping
Quick Answer: Wrinkles in the liner usually result from groundwater pressure, improper fit, or shifting walls. A slipping liner means the bead is not properly seated.
Causes:
- Low water temperatures during install
- Poorly leveled pool base or foam cove issues
- Water table pressure pushing upward
Fix It:
- Warm the liner with hot water or sunlight and smooth wrinkles with a pool brush
- Use a liner lock bead wedge to secure loose beads into the track
- Install a drainage system if groundwater is the recurring cause
Recommended Product: A Liner Lock Kit ensures your liner stays in place through seasonal shifts.
3. Flooding or Water Accumulation Around Pool
Quick Answer: Flooding near a semi-inground pool is caused by improper site grading or inadequate drainage systems.
What to Check:
- Gutters or landscape runoff directing water toward the pool
- Incorrect slope away from the pool structure
- Missing gravel or drainage tile around the base
How to Solve It:
- Regrade the yard to slope away from the pool (minimum 1” drop per foot)
- Install perforated drain pipe around the pool base
- Add crushed stone or river rock to help with water flow and appearance
Upgrade Tip: Consider adding a sump pump system in high water table areas to actively redirect water.
4. Uneven Settling or Sinkholes
Quick Answer: If part of your semi-inground pool base starts to sink or settle, it’s typically due to poor soil compaction or underground erosion.
Warning Signs:
- Deck gaps forming
- Pool wall movement or leaning
- Sudden changes in water level
How to Handle It:
- Backfill voids with flowable fill or compacted gravel
- Monitor water chemistry to prevent soil washout from plumbing leaks
- Avoid planting large root systems nearby
Professional Tip: Hire a geotechnical expert if your yard has clay or sandy soil to ensure stability.
5. Pool Equipment Malfunctions
Quick Answer: Equipment like pumps, filters, and heaters may malfunction due to flooding, improper voltage, or restricted water flow.
Common Issues:
- Pump won’t start (check breaker or timer settings)
- Filter pressure too high (clean cartridge or backwash sand)
- Heater shuts off (inspect for flow issues or low voltage)
Maintenance Tip: Elevate pool equipment on concrete slabs or polymer blocks to prevent flood damage.
Suggested Product:
Use a Weatherproof Pool Equipment Cover to protect components from seasonal wear and excess moisture.
6. Deck Cracking or Heaving
Quick Answer: Concrete or paver decking around a semi-inground pool can crack due to freeze-thaw cycles, poor soil prep, or hydrostatic pressure.
How to Prevent and Repair:
- Install expansion joints every 10–12 feet in concrete
- Use compacted gravel base before laying pavers
- Seal cracks with flexible polyurethane caulk to prevent water infiltration
Pro Upgrade: Consider rubber deck coatings or foam underlayment to improve flexibility and crack resistance.
7. Plumbing or Skimmer Leaks
Quick Answer: Leaks in plumbing or skimmer areas can occur from ground shifting, freezing, or improperly sealed fittings.
Signs to Watch For:
- Water level dropping faster than normal evaporation
- Wet or muddy spots near return lines or skimmer box
- Air bubbles coming through jets
How to Fix:
- Pressure test lines to isolate the leak
- Use epoxy putty to patch minor cracks in skimmer housing
- Reseal threaded fittings using Teflon tape and pipe dope
Recommended Product: Fix-A-Leak Pool Leak Sealer works well for minor, non-structural plumbing leaks.
Semi-Inground Pool Troubleshooting Table
| Problem | Cause | Solution |
|---|---|---|
| Wall shifting | Uneven backfill, water pressure | Rebackfill with gravel, monitor water level |
| Liner wrinkles | Cold install, groundwater, liner misalignment | Warm liner, re-seat bead, add liner lock |
| Flooding | Poor drainage or slope | Regrade, install drain tile or French drain |
| Sinkholes | Soil erosion or plumbing leaks | Backfill with flowable fill, repair leaks |
| Cracking deck | Freeze-thaw cycles, settling | Add joints, seal cracks, use flexible coatings |
Best Practices for Preventing Semi-Inground Pool Issues
Before Installation:
- Choose well-draining soil or install drainage systems
- Compact soil in layers to avoid settling
- Use foam or sand cove around the base
After Installation:
- Backfill evenly with gravel, not loose soil
- Keep the pool full of water during backfilling
- Install proper grading and water runoff controls
Conclusion: Keep Your Semi-Inground Pool Problem-Free
Semi-inground pools are a stylish and smart investment, but only if installed and maintained correctly. From shifting walls to liner issues and drainage trouble, most problems can be avoided or fixed with a little know-how and the right tools.
Need help? Use this guide to diagnose and repair common issues fast—or work with a pool pro to protect your investment and extend your pool’s life for years to come.