بررسی آلودگی باکتریایی در آب‌های بطری شده و مقایسه آن با آب آشامیدنی شبکه توزیع شهر سمنان در سال 91

Background and purpose: Heterotrophic plate count (HPC) is commonly used to assess the general microbiological quality of drinking water. HPC must be less than 500 colonies per milliliter in drinking water. The aim of this study was to compare the heterotrophic bacteria of bottled water and drinking water distribution system and their relationship with water quality parameters. Materials and methods: In this study 21 samples of bottled water belonging to seven domestic brands and 15 samples of drinking water from water distribution system in Semnan were analyzed and compared for HPC. The Relationship between HPC with pH, temperature, turbidity and free residual chlorine were also determined in drinking water distribution system. Results: The results showed that HPC was lower in bottled water compared with that of the tap water. HPC has increased when the temperature increased. In contrast, HPC has decreased when free residual chlorine increased. Turbidity and pH did not influence the HPC in drinking water distribution system. Conclusion: The quality of all bottled water was consistent with the Iranian drinking water standards and also the standard levels proposed by World Health Organization. However, HPC was found more in some parts of distribution system where the residual chlorine was low.