The Saen Saeb canal, a transportation route in the central of Bangkok, nowadays is polluted with domestic wastewater. People along the canal still use the Saen Saeb water for watering plants. However, the effect of Saen Saeb water usage on plant growth and soil microorganisms is not well understood. The present study showed the effect of Saen Saeb water on the growth of Chinese kale (Brassica alboglabra), tomato (Lycopersicon esculentum), and Dendrobium orchid (Dendrobium Sonia ‘Earsakul’) at greenhouse and sterile conditions. We found that the Saen Saeb water reduced the growth of Chinese kale and Dendrobium orchid in the greenhouse condition as well as the growth of the Chinese kale and tomato in the sterile condition. Moreover, the Saen Saeb water reduced the amount of rhizosphere microorganisms of the Chinese kale to five times less than that of tap water. Thus, this may affect the plant growth.
