Can Spiders Swim? Spider Behavior Around Water

The short answer is: some can, some cannot, and a few are surprisingly good at it. Spider interactions with water are more complex and fascinating than most people realize.

Can Spiders Swim?

Most spiders cannot truly swim in the way fish or frogs do. However, many species have adaptations that allow them to survive encounters with water:

Walking on Water

Many spider species can walk on the surface of still water. Their lightweight bodies and water-repellent leg hairs allow them to exploit surface tension, effectively standing on the water's surface like water striders. Wolf spiders and some jumping spiders commonly use this ability.

Rowing and Sailing

Some spiders can "row" across water surfaces using their legs, and a few species can raise their legs or body to catch the wind and "sail" across ponds and streams. Research published in 2015 showed that many common spider species can use wind-powered sailing to cross bodies of water.

Diving

A few remarkable spider species are semi-aquatic:

• Diving bell spider (Argyroneta aquatica): The only truly aquatic spider, found in Europe and Asia. It lives underwater in a silk "diving bell" filled with air, spending its entire life submerged.
• Fishing spiders (Dolomedes spp.): Found in North America, these large spiders hunt on the water's surface. They can submerge entirely and remain underwater for up to 30 minutes by trapping air in their body hairs.

Surviving Submersion

Many spider species can survive being submerged for extended periods:

• Spiders trap a thin layer of air in their body hairs, creating a temporary air supply.
• Some species can survive underwater for hours to days by entering a state of reduced metabolic activity.
• This is why you sometimes see spiders apparently "come back to life" after being washed down a drain.

Spiders in Bathrooms and Water

The common belief that spiders crawl up through drains is largely a myth. Modern plumbing includes water traps that prevent this. Spiders found in bathtubs and sinks typically fell from walls or ceilings and became trapped — the smooth surfaces are too slippery for them to climb out.

For more on why spiders appear in bathrooms and how to prevent it, see our dedicated guide.

Does Water Kill Spiders?

Flushing a spider down the drain or spraying it with water may not kill it. Many spiders can survive submersion for surprising lengths of time. If you want to remove a spider, capturing and releasing it outdoors is more reliable than drowning it.

Practical Implications

Understanding spiders' relationship with water helps with pest control:

• Rain drives ground-dwelling spiders indoors.
• Reducing moisture in basements and bathrooms makes these areas less attractive to moisture-loving species.
• Spiders found near water features are likely fishing spiders or wolf spiders — both harmless.
• Water-based spray treatments remain effective since the active ingredients, not the water itself, kill spiders.

Spiders and Floods

During flooding events, spiders demonstrate remarkable survival strategies:

• Mass ballooning: After floods in Australia, entire fields have been covered in silk as millions of spiders balloon to higher ground simultaneously. The result, sometimes called "angel hair," is a dramatic visual reminder of spiders' survival capabilities.
• Raft building: Some ground-dwelling spiders form rafts of silk and debris to float on floodwaters.
• Tree climbing: Ground-dwelling species climb vegetation to escape rising water, sometimes congregating in large numbers on elevated surfaces.

These behaviors explain why spider activity often increases in and around homes after heavy rain — displaced spiders are seeking any available high, dry ground.

Can You Drown a Spider?

While many people flush spiders down toilets or drains, this method is not as effective as it might seem. Spiders can survive for hours underwater by trapping air in their body hairs. They may simply wash through the plumbing and emerge elsewhere, or survive in the water trap.

More reliable removal methods include:

• Capturing and releasing outdoors
• Vacuuming (dispose of the bag or canister contents)
• Using sticky traps

For more spider facts and behavior, see do spiders sleep, types of spiders, and our complete guide to spiders.

Expert Insights

I have been asked about spiders and water countless times during my 15 years in pest management. One memorable call involved a homeowner who found a large wolf spider in her swimming pool. The spider was very much alive and walking on the surface tension of the water. I explained that many spider species can survive on water surfaces and some can even dive beneath the surface for short periods. — Sarah Mitchell, BCE

Sources and References

• University of California Riverside Spider Research
• Burke Museum of Natural History and Culture
• Ohio State University Extension

Main Causes

Spiders end up near or in water for the same reason they appear anywhere else: prey and shelter. Moisture-loving prey insects such as mosquitoes, midges, and shore flies concentrate near standing water, attracting hunting spiders. Heavy rain displaces ground-dwelling spiders from flooded burrows and saturated soil, causing them to move to any elevated dry surface - including interior spaces. Wolf spiders in particular migrate indoors after rainstorms because they hunt at ground level and their microhabitats flood quickly. Bathroom and basement encounters are rarely the result of spiders entering through drains; they almost always represent spiders that entered through gaps in the structure while following prey or seeking shelter from wet conditions outside.

How to Identify

Spiders found near water indoors are most often wolf spiders or fishing spiders. Wolf spiders are brown to gray, 10 to 35 mm in body length, hairy, and move quickly across open surfaces. Fishing spiders (Dolomedes spp.) are similar in color but typically larger - females can reach 25 mm in body length with a leg span approaching 75 mm - and may have a pale stripe along each side of the cephalothorax. Neither species builds webs indoors. Cellar spiders and house spiders found in bathroom corners are web builders and are not related to water; they simply prefer the humid conditions. No species found near indoor water sources in North America is medically significant.

Risk and Severity

Spiders encountered near water, including pools, bathrooms, and basement drains, pose no meaningful medical risk. The species most likely to appear near indoor water - wolf spiders and cellar spiders - are harmless. Fishing spiders, while impressively large, are also not medically significant. Flushing spiders down drains is an ineffective removal method, as many species can survive submersion for hours by trapping air in their leg hairs. A spider that survives flushing may simply exit the plumbing elsewhere. Physical capture and outdoor release is more reliable and eliminates the spider without the possibility of survival in the drain system.

Prevention

Reduce indoor moisture to make basements and bathrooms less hospitable to spiders and the prey insects that attract them. Run exhaust fans during and after showers. Fix leaking pipes and faucets. Use a dehumidifier in basement spaces to keep relative humidity below 50 percent. Seal gaps around pipe penetrations where spiders enter from outdoors. Install intact door sweeps on any exterior entry at ground level. Remove debris and standing water from the property perimeter to reduce the rain-displacement events that push ground-dwelling spiders indoors. These measures address the underlying conditions rather than individual spiders.

Solutions and Actions

For most spider species the goal is removing webs and reducing prey rather than chemical treatment. Vacuum or sweep down all visible webs weekly, including egg sacs, in garages, basements, attics, eaves, and exterior corners. Reduce indoor insect populations by maintaining screens, sealing entry points, and addressing any active pest issue — fewer insects means fewer spiders. Apply a residual insecticide barrier to the foundation perimeter, around windows and doors, and in eaves to deter newly arriving spiders. For confirmed black widow or brown recluse populations in storage areas, use professional pest control, wear long sleeves and gloves when handling stored items, and shake out shoes and clothing left in garages or basements. Single sightings indoors without webs are usually transient and need no chemical response.

Frequently Asked Questions

Can spiders survive in water?

Many spider species can survive on water for extended periods by using surface tension to stay afloat. Some species, like fishing spiders (Dolomedes), are semi-aquatic and can walk on water, dive beneath the surface, and even catch small fish and aquatic insects.

Will spiders drown in my pool?

Spiders that fall into pools may not drown immediately. Many can survive on the water surface for hours. However, most terrestrial spiders will eventually drown if they cannot reach the pool edge. Using a pool cover and keeping vegetation trimmed away from the pool edge can reduce spider encounters.

Do spiders come up through drains?

Despite the common myth, spiders rarely enter homes through drains. Spiders found in bathtubs and sinks usually fell in from above and cannot climb the smooth surfaces to escape. The curved water trap in drain pipes prevents anything from traveling up through the plumbing.

What should I recheck first for spiders around water?

Recheck the exact place, timing, and repeated signs connected with spiders around water before changing your plan. A single sighting or old web can mean something very different from fresh activity in several rooms. Confirm whether insects, clutter, moisture, gaps, or stored items are supporting the issue, then match the response to what you actually found.