Understanding point-of-use tap water quality: From instrument measurement to intelligent analysis using sample filtration

In most cases, point-of-use tap water quality is not routinely monitored due to widely-dispersed sampling sites and the costly tests. Although previous studies have revealed the variation of drinking water quality during distribution in municipal networks, the influence of aging pipes in buildings on quality is still unknown and this makes it difficult for water utilities to conduct regular maintenance. Herein, we have undertaken a survey of tap water samples across 8 districts in Beijing (China) to evaluate the potential effects of pipe age on point-of-use water quality, including turbidity, organic matter characteristics, and bacterial community. By grouping the collected samples according to the pipe age and source water respectively, the results suggested that bacterial diversity is significantly influenced by the pipe age. However, bacterial community structure is clearly influenced by the source water. Similarly, aging pipes in buildings are also responsible for the deterioration of the final water quality, and their effects have been closely linked to selected water quality parameters by evaluating the relevant factors. Moreover, the interrelationships between physico-chemical parameters and bacteria abundance were identified. For example, pH, Ca2+, Mg2+, Na+ and K+ showed a positive relationship with Bacillus abundance. In addition, an intelligent analysis method for understanding pipe age, organic matter concentration, and hardness (i.e., Ca2+ and Mg2+ concentration), based on image analysis of filtered membranes has been developed. The accuracy of prediction was encouraging, but can be improved with the collection of more data from tap water samples. We expect that this method can be exploited by the public to monitor their tap water and provide a feasible and cost-effective approach for water suppliers to locate aging/deteriorating pipes which need to be replaced or maintained.

Automated summary

This study aimed to evaluate the influence of pipe age on point-of-use water quality. The results showed that bacterial diversity is affected by pipe age, while bacterial community structure is influenced by the source water. Aging pipes in buildings were also found to contribute to the deterioration of water quality. The study identified the relationships between physico-chemical parameters and bacteria abundance, and developed an image analysis method for predicting pipe age, organic matter concentration, and hardness.