Introduction
Is your pool losing water faster than usual? One of the most common sources of mystery leaks is the pool skimmer—especially where it meets the concrete or the pool wall. Learning how to seal a leaking pool skimmer can prevent costly water loss, protect your equipment, and help you avoid major repairs down the line. This guide walks you through how to detect, diagnose, and seal a skimmer leak quickly and effectively.
Why Sealing a Pool Skimmer Leak Matters
The pool skimmer plays a critical role in circulating and cleaning water, but it’s also a common spot for leaks. Over time, the connection between the skimmer body and the pool structure can crack, deteriorate, or separate.
If left unsealed, a skimmer leak can:
- Waste hundreds of gallons of water weekly
- Spike your water and chemical costs
- Cause erosion around the pool shell
- Lead to pump cavitation or equipment failure
Promptly sealing the leak will preserve your water level, extend equipment life, and prevent expensive damage to the surrounding pool area.
Step-by-Step Guide to Sealing a Leaking Pool Skimmer
Step 1: Confirm the Skimmer Is the Leak Source
Before sealing, you need to confirm that the skimmer is leaking and not another part of the system.
Do a Bucket Test:
- Fill a bucket with pool water and place it on the pool step.
- Mark the water level inside the bucket and the pool water level outside.
- Run the pool as usual for 24 hours.
- If the pool water drops more than the bucket, you have a leak.
Isolate the Skimmer:
- Turn off the pump.
- Plug the skimmer with a rubber expansion plug.
- Wait 24 hours.
- If the leak stops, the skimmer is the source.
💡 Tip: Use food coloring around the skimmer throat or body while the pump is off. Watch for it getting pulled into cracks.
Step 2: Drain Water Below the Skimmer
To access the skimmer crack properly, lower the pool water level about 2–3 inches below the skimmer opening.
- Use the pool pump’s “waste” setting or a submersible pump.
- Make sure the skimmer area is dry before applying sealant.
⚠️ Caution: Don’t drain the pool too much, especially in fiberglass or vinyl pools, as it could cause structural damage.
Step 3: Clean the Skimmer Area
Use a brush and mild detergent to clean around the skimmer faceplate, throat, and body. Remove:
- Dirt
- Debris
- Algae
- Loose sealant or grout
Dry the area thoroughly with a towel or cloth.
💡 Tip: Use isopropyl alcohol to wipe down the surface for better adhesive bonding.
Step 4: Choose the Right Sealant
For most skimmer leaks, especially at the joint where the plastic skimmer meets the concrete, a flexible underwater pool sealant or epoxy putty is recommended.
Options include:
- Pool silicone sealant – Good for minor cracks or sealing around fittings
- Epoxy putty – Best for structural cracks or larger gaps
- Hydraulic cement – Ideal for fixing leaks in the concrete base or around skimmer housing (not for vinyl pools)
💡 Product Tip: Look for “underwater sealant” or “wet application safe” for best results.
Step 5: Apply the Sealant
For Sealant Tubes (Silicone/Adhesive):
- Cut the nozzle to the desired width.
- Load into a caulk gun.
- Apply the sealant generously along the crack or joint.
- Smooth with a gloved finger or caulking tool.
For Epoxy Putty:
- Cut and knead the putty until it’s a uniform color.
- Press it firmly into the crack.
- Smooth it out and blend into the surface.
For Hydraulic Cement:
- Mix according to instructions (sets fast—work quickly).
- Press into crack or void using a putty knife or trowel.
⚠️ Always follow manufacturer instructions for curing times before refilling water or running the pump.
Step 6: Refill Pool and Monitor
Once the sealant has fully cured (usually 24–48 hours depending on the product):
- Refill the pool to normal water level.
- Turn the pump back on.
- Monitor water level over the next few days.
If the water holds and no dye is drawn into cracks, the repair is successful.
💡 Tip: Take a photo of your water level and check after 24 hours to track any subtle changes.
Common Mistakes to Avoid
1. Sealing a Wet Surface
Most sealants require a dry surface to adhere properly.
✅ Drain below the skimmer and thoroughly dry the area before applying.
2. Using the Wrong Product
Household caulk or regular silicone won’t hold up in chlorinated water.
✅ Use pool-rated sealants or underwater epoxies only.
3. Skipping Surface Prep
Dirt or algae can prevent sealant from bonding.
✅ Always clean and prep the surface before sealing.
4. Overlooking Hidden Cracks
Leaks often occur behind the faceplate or inside the skimmer throat.
✅ Inspect all around the skimmer housing—not just the visible front.
5. Not Waiting for Cure Time
Refilling too soon can wash out uncured sealant.
✅ Follow the curing instructions exactly—patience pays off.
Extra Tips & Pool Hacks
- Install a skimmer faceplate gasket if yours is worn or leaking around the screws.
- Check the skimmer lid—a cracked lid can let debris and rain in, putting extra pressure on seals.
- Use a mirror and flashlight to inspect hard-to-see cracks inside the skimmer throat.
- Consider a skimmer saver plug for temporary sealing if you can’t do a full repair right away.
🧼 Related Tip: [Check out our guide on how to clean your skimmer basket] to maintain healthy water flow and prevent leaks from pressure buildup.
Conclusion
A leaking skimmer doesn’t always mean a major repair—many leaks can be sealed quickly with the right tools and technique. By following these steps to detect, clean, seal, and test your skimmer, you’ll restore your pool’s water level, prevent costly damage, and enjoy peace of mind all season long.
👉 Bookmark this guide for your next pool inspection or leak check!