How many lice live in a pool? - briefly
No lice are found in a swimming pool; the environment is unsuitable for their survival. Chlorinated water kills them almost immediately, resulting in a count of essentially zero.
How many lice live in a pool? - in detail
The presence of lice in a swimming pool depends on species, environmental conditions, and human activity. Head lice (Pediculus humanus capitis) cannot survive long in chlorinated water; chlorine concentrations of 1–3 ppm kill them within minutes. Consequently, the viable population of head lice in a typical public pool is effectively zero.
Body lice (Pediculus humanus humanus) share the same susceptibility to chlorine and require clothing for habitat. Since swimmers rarely wear clothing that supports lice development, their numbers in a pool are also negligible.
Pubic lice (Pthirus pubis) are similarly vulnerable to chlorine and do not thrive in water. Their detection in pool water is rare and limited to accidental transfer on skin, which chlorine eliminates quickly.
Empirical studies on lice survival in swimming environments report the following:
- Immediate mortality (≤5 min) at chlorine levels ≥1 ppm for all three human lice species.
- No egg (nit) hatching observed after 10 min exposure to standard pool disinfectant concentrations.
- Laboratory replication of pool conditions shows complete eradication of adult lice within 2 min of exposure.
Given these data, a well‑maintained pool with proper chlorination will host no living lice. In poorly maintained or non‑chlorinated bodies of water, occasional transient presence is possible, but numbers remain low because lice require human hosts for feeding and reproduction. The maximum theoretical count in such an environment would be limited to the number of infested individuals who enter the water, typically a handful in any given session.
Therefore, the realistic estimate for lice inhabiting a properly treated swimming pool is zero. Any detection of live lice would indicate a failure in water treatment protocols.