Bidet toilet seats with warm-water tanks: residual chlorine, microbial community, and structural analyses.

Keiko Asakura,Kazuyuki Omae,Makiko Nakano,Toru Iyo,Mutsuko Yamada

doi:10.2166/wh.2015.057

Keiko Asakura, Kazuyuki Omae + Show 3 more

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https://doi.org/10.2166/wh.2015.057

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Abstract

Despite the reported health-related advantages of the use of warm water in bidets, there are health-related disadvantages associated with the use of these toilet seats, and the bacterial research is sparse. We conducted a survey on the hygienic conditions of 127 warm-water bidet toilet seats in restrooms on a university campus. The spray water from the toilet seats had less residual chlorine than their tap water sources. However, the total viable microbial count was below the water-quality standard for tap water. In addition, the heat of the toilet seats' warm-water tanks caused heterotrophic bacteria in the source tap water to proliferate inside the nozzle pipes and the warm-water tanks. Escherichia coli was detected on the spray nozzles of about 5% of the toilet seats, indicating that the self-cleaning mechanism of the spray nozzles was largely functioning properly. However, Pseudomonas aeruginosa was detected on about 2% of the toilet seats. P. aeruginosa was found to remain for long durations in biofilms that formed inside warm-water tanks. Infection-prevention measures aimed at P. aeruginosa should receive full consideration when managing warm-water bidet toilet seats in hospitals in order to prevent opportunistic infections in intensive care units, hematology wards, and other hospital locations.

Highlights

The spray water is warmed to a suitable temperature in a tank, whereas in the on-demand type the water is warmed as needed inside a tube
The geometric means (GM) of residual chlorine in the spray water of warm-water bidet toilet seats and in tap water was 0.04 mg/L and 0.24 mg/ L, respectively, which represented a significant difference (P < 0.01). This result demonstrated that there is clearly less residual chlorine in spray water than in tap water (Table 1). When these data were log-normalized, it became clear that artificial factors caused the residual chlorine to disappear in the spray water
Frequent inflow of tap water into a toilet’s warm-water tank is needed to maintain the chlorine concentration in spray water; that is, the residual chlorine concentration cannot be maintained without frequent use

Summary

Introduction

Warm-water bidet toilet seats are equipped with a device that sprays warm water (spray water) on the external genitalia and. A toilet seat equipped with bidet functions first appeared on the market in the United States in 1964 (Altman ). A consumer behavior survey conducted by the Japanese Cabinet Office showed that 74.0% of households had warm-water bidet toilet seats in March 2013, with 102.9 units per 100 households (effectively one per household) (Cabinet Office Government of Japan ). There are two types of warm-water bidet toilet seats: tank types and on-demand types.

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