How to Get Waterbugs Out of Your Pool—And Keep Them Gone

Reviewed by a Certified Pool Technician (CPT)

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The Short Answer

Waterbugs appear in pools because algae, organic debris, or insect larvae serve as their food source. Removing the bugs alone won't solve the problem you need to clean the pool, restore proper water chemistry, eliminate algae, and maintain regular filtration to remove the food supply that attracts them. Identify which species you have first: water boatmen are harmless algae-eaters; backswimmers bite and require a more urgent removal approach.

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Seeing bugs in your pool water is alarming, but understanding what you're actually dealing with changes both the urgency and the treatment. There are two common pool aquatic insects that most pool owners encounter: water boatmen and backswimmers, and they're related in a way that matters for treatment: backswimmers eat water boatmen, which means a backswimmer infestation often follows a water boatmen infestation. Fix the underlying cause (algae and organic debris), and both species eventually leave.

 

How to Tell if You Have Water Boatmen or Backswimmers

These two species look similar but behave very differently and the difference matters for how urgently you need to act.

Water Boatmen (Corixidae)

Identification:

• Oval, flattened body approximately 3/8 to 5/8 inch long

• Brown or olive color with fine crosshatching on the back

• Paddle-like hind legs used for swimming

• Swim right-side up, this is the key visual identifier

• Often seen resting near the pool bottom or walls

• Can fly (which is how they find your pool)

Behavior: Water boatmen are herbivores. They feed primarily on algae and microscopic plant material in the water. They are completely harmless to humans and pets, they do not bite. If you have water boatmen, you have algae (even if it's not yet visible), because that's what they're eating.

Threat level: Low to none for swimmers. High as an indicator of a problem; their presence signals active algae growth.

Backswimmers (Notonectidae)

Identification:

• Similar oval body shape, slightly larger than water boatmen (up to 3/4 inch)

• Pale or whitish back with dark markings appears lighter on top

• Swim upside down back is on the underside while swimming; this is the definitive visual identifier

• Move quickly and erratically compared to the more deliberate water boatmen

• Long oar-like hind legs that extend to the sides while swimming

Behavior: Backswimmers are predators. They eat water boatmen, mosquito larvae, small aquatic insects, and occasionally tadpoles. They are attracted to pools that already have water boatmen. Unlike water boatmen, backswimmers can and will bite the bite is painful and has been compared to a bee sting. They are capable of flying and relocating between pools.

Threat level: Significant bites are painful, and pets swimming in the pool can be bitten repeatedly. If you have backswimmers, you almost certainly had water boatmen first.

 

Do Waterbugs Mean Your Pool Has Algae?

Almost certainly yes, and this is the most important connection for understanding why bugs keep coming back.

Water boatmen are almost exclusively found in water with an active algae or microorganism population. Per university-based aquatic entomology research (University of Florida's Featured Creatures database, which documents pool-relevant aquatic insects): water boatmen are strongly associated with algae-containing water and are one of the earliest biological indicators of an emerging algae problem in pools.

What this means practically:

• If you see water boatmen, test your water. Chlorine is almost certainly depleted or pH is high enough that chlorine is ineffective.

• The algae feeding water boatmen may not yet be visible as color, water can look clear blue while harboring enough algae biomass to support a water boatmen population.

• Killing the bugs without treating the algae only temporarily removes them. They will return as long as the food source remains.

The backswimmer connection: Backswimmers are secondary, they arrive to eat the water boatmen. A pool with visible backswimmers has almost certainly had a water boatmen infestation for at least several days. Treating algae eliminates the water boatmen food source, which eliminates the reason for backswimmers to stay.

 

Can Waterbugs Bite People or Pets?

Water boatmen: No. They have no mechanism for biting humans or pets and pose zero health risk to swimmers. They are a nuisance indicator problem, not a safety problem.

Backswimmers: Yes, and painfully. Backswimmers use the same beak structure they use for hunting prey to bite larger animals (including humans and pets) when they feel threatened. The bite injects a small amount of digestive fluid that causes immediate localized pain, redness, and swelling, comparable to a bee sting. Unlike bees, backswimmers can bite multiple times. They will bite if they come into contact with skin in the water.

If a pet swims in a backswimmer-infested pool: Dogs and cats swimming in heavily infested water can receive numerous bites. Pets may react strongly to backswimmer bites, watch for pawing at face or eyes (indicating a bite near those areas) and localized swelling.

Safe swim threshold: If water boatmen are present but no backswimmers, swimming is generally safe but unpleasant. If backswimmers are visible, don't allow children or pets in the pool until the infestation is treated and bugs are no longer visible.

Why Waterbugs Keep Coming Back

The frustrating recurring cycle has a consistent explanation: the food source wasn't fully eliminated.

Reason 1: Algae wasn't fully killed. A shock treatment that wasn't strong enough, or that was applied without brushing first, may have killed visible algae while leaving microscopic algae and spores that continue to feed water boatmen. Water that clears up after shocking can still have enough microscopic algae to attract and sustain bugs.

Reason 2: Chemistry wasn't maintained after treatment. Chlorine that drops below 1 ppm creates an opening for algae to re-establish. Without consistent chemistry, the food source rebuilds and bugs return.

Reason 3: Debris isn't being removed. Leaves, pollen, and organic matter at the bottom of the pool provide both nutrition for algae and a direct food source for water boatmen. Organic debris that isn't vacuumed sits and decomposes, sustaining the bug population even when algae is controlled.

Reason 4: Pool lighting at night. Both water boatmen and backswimmers are attracted to light. Lights on the water surface or bright pool lights at night attract flying insects, which in turn attract backswimmers. Reduce or redirect poolside lighting during peak bug season.

Reason 5: Nearby algae-heavy water sources. Ponds, ditches, or bird baths near the pool are bug reservoirs. Water boatmen that fly in from nearby natural water will be drawn to algae in your pool even after you've treated it. Prevention (see below) matters as much as treatment.

How to Remove Waterbugs from Your Pool: Step-by-Step

Step 1: Don't Use Dish Soap (The Myth)

Many online guides recommend adding dish soap to break the surface tension and drown water bugs. This temporarily works on the surface but doesn't address the underlying algae, creates foam, disrupts pool chemistry, and doesn't prevent reinfestation. Skip it.

Step 2: Test Water Chemistry

Before adding anything, test free chlorine, pH, and alkalinity. This tells you how bad the chemistry situation is and what correction the pool needs.

Step 3: Brush All Pool Surfaces

Brush walls, floor, steps, and corners thoroughly. This physically disrupts algae colonies (especially in early stages) and exposes algae cells to the shock treatment you're about to add. Don't skip this step, it significantly improves shock effectiveness against algae.

Browse our pool brush collection for brushes matched to your pool surface type.

Step 4: Shock at Treatment Dose

Add chlorine shock at treatment-level dose, not maintenance dose. For a standard green-tending or algae-suspected pool: 2 lbs cal-hypo per 10,000 gallons at dusk. For visible algae or confirmed bug infestation: increase to 3 lbs per 10,000 gallons.

This kills algae and deprives waterbugs of their food source.

Step 5: Run the Filter Continuously for 24 Hours

Keep the pump running through the treatment period. Dead algae cells need to be captured by the filter; stagnant water allows algae to persist in dead-flow zones. For help with filter timing, see our guide to how long to run your pool pump.

Step 6: Backwash or Clean the Filter

After 24 hours of treatment circulation, clean the filter to remove captured algae and debris. See our filter backwashing guide for the full process.

Step 7: Vacuum Dead Debris

Once algae is dead and the pool is clearing, vacuum the floor and walls to remove settled organic debris that could sustain a re-infestation.

Step 8: Physically Remove Remaining Bugs

After treatment, any surviving bugs can be removed with a fine-mesh leaf net. Skim the surface and walls, then immediately dispose of the bugs away from the pool, they can fly back in. A second sweep the following day usually catches stragglers.

Best Pool Chemicals to Prevent Waterbugs

The chemical strategy is about eliminating algae, not directly killing bugs.

Chlorine (primary): Maintain free chlorine at 1–3 ppm consistently. Chlorine that drops below 1 ppm creates the opening for algae and therefore bugs. Test at minimum twice per week during summer.

Algaecide (preventive): A monthly maintenance dose of polyquat or copper-based algaecide prevents algae from establishing between chlorine treatment cycles. Algaecide doesn't kill bugs directly but removes their food source. For algaecide selection, see our guide to the best algaecides for pools.

pH management: Chlorine is most effective at pH 7.2–7.6. At pH 8.0, only about 20% of free chlorine is active, meaning bugs can find algae even in a pool testing at 3 ppm chlorine if pH is too high. Test pH alongside chlorine every time.

Pool chemistry balance: For a complete overview of all parameters that affect sanitizer effectiveness, see our guide to what's the deal with pool chemical balance.

Seasonal Tips to Prevent Waterbug Infestations

Spring opening: Before re-filling or reopening after winter, clean any organic debris (leaves, pollen, debris) that settled during the closed period. Opening to algae-free, balanced water prevents the first bug wave of the season.

Early summer (peak bug season): Water boatmen and backswimmers are most active May through August when water temperatures are warm enough for rapid algae growth. Increase testing frequency to 3× per week during this period. Test after any heavy rain, which dilutes chemistry and introduces phosphates that feed algae.

During pollen season: Pollen settles on pool surfaces and adds organic load that can promote algae. Skim the surface daily during heavy pollen periods and vacuum weekly. For more on managing pollen in pools, see our pollen removal guide.

Night lighting management: Reduce or redirect bright lights near the pool during May through August. Water boatmen and backswimmers are attracted to light and will fly toward illuminated pool surfaces. Consider using yellow or amber lights near the pool, these wavelengths are less attractive to flying insects than white or blue-white lights.

Bird baths and nearby water sources: If you have bird baths, outdoor pet water dishes, or decorative water features within 50 feet of the pool, empty and refill them weekly during bug season. These serve as staging areas for waterbugs before they migrate to the pool.

 

Common Mistakes That Attract Waterbugs

Not brushing before shocking. A shock treatment applied without brushing first doesn't penetrate algae colonies efficiently. The algae that feeds water boatmen survives, and bugs return within days.

Under-dosing shock. A maintenance dose of chlorine won't eliminate an active algae population. Use treatment dose (2–3× maintenance) when bugs are present.

Turning off the pump at night. Algae establishes fastest in stagnant water. Running the pump only during the day leaves overnight water untreated. During active bug issues, run the pump 24 hours until the pool is clear.

Leaving pool lights on at night during peak season. Bright white pool lights attract flying waterbugs from surrounding areas. Turn off or dim pool lighting at night during June through August, or switch to insect-repelling amber/yellow lights.

Not vacuuming after treatment. Dead algae and organic debris that settles to the pool floor after treatment continues to serve as nutrition for any remaining bugs and for new algae growth. Vacuum thoroughly after every shock treatment during bug season.

Ignoring nearby water sources. A beautifully maintained pool 30 feet from a stagnant bird bath is still going to attract waterbugs from that bird bath. Manage all standing water in the surrounding area.

Frequently Asked Questions

How do I get water bugs out of my pool?

Shock the pool at treatment dose after brushing all surfaces, run the filter continuously for 24 hours, backwash the filter, vacuum dead debris, and maintain free chlorine at 1–3 ppm. The bugs will leave when their algae food source is eliminated. Physically remove any remaining stragglers with a fine-mesh net.

What are the water bugs in my pool?

Almost certainly water boatmen (harmless algae-eaters that swim right-side up) or backswimmers (predatory insects that swim upside down and bite painfully). Both indicate algae in the pool water; water boatmen directly eat algae; backswimmers eat the water boatmen.

Do pool water bugs bite?

Water boatmen: no. Backswimmers: yes, they deliver a painful bite similar to a bee sting and will bite multiple times. If you see insects swimming upside down, you have backswimmers and should keep people and pets out of the pool until treated.

Why do water bugs keep coming back to my pool?

Because the food source, algae and organic debris, wasn't fully eliminated. Bugs don't stay in pools for the water; they stay for the food. Consistent chemistry (free chlorine 1–3 ppm, pH 7.2–7.6), regular brushing, and monthly algaecide maintenance eliminate the conditions that sustain bug populations.

Does dish soap get rid of pool water bugs?

Temporarily, dish soap breaks surface tension and can trap bugs, but it creates foam, disrupts pool chemistry, and doesn't address the algae causing the infestation. Proper treatment (shock + chemistry + filtration) is the only lasting solution.

Are water bugs in pools dangerous?

Water boatmen are harmless. Backswimmers bite, causing localized pain and swelling. Neither species transmits disease. The more significant concern is that their presence confirms you have an algae problem, which in a heavily affected pool can harbor bacteria if chlorine is severely depleted.