A study has found that the water quality of a home can differ in each room and change between seasons, challenging the assumption that the water in a public water system is the same as the water that passes through a building’s plumbing at any time of the year.
“This study reveals that drinking water in the service line water is clearly not the same quality at your faucet,” said Andrew Whelton, a Purdue University associate professor of civil engineering and environmental and ecological engineering. Researchers from Purdue, the University of Memphis and Michigan State University conducted the study, published in the journal Building and Environment.
The study is so far the largest and most intensive investigation of water quality over time and throughout a single house. The researchers collected data 58 times at the house over the course of a year, logging more than 222,000 hours and 2.4 billion records.
While more studies at this scale are needed before generalizing findings to other American homes, the results are concerning: 10% of the time, disinfectant was not found in the water entering the house studied, meaning that the water was not properly protected from bacteria growth once it entered the home.
There were also increases in water pH inside the house and large fluctuations in organic carbon. Either can indicate drastic changes in drinking water chemistry.
“After water enters a home it continues to age. Older water is more likely to have contaminants that are problematic. Because the quality of water delivered to a single home can vary significantly, and building plumbing can change the water too, predicting drinking water safety at every building faucet is currently not possible,” Whelton said.
The researchers note that different plumbing materials, a varying number of house occupants and other factors could affect the water quality of a home. These factors warrant future study.
More studies like this one could inform the development of new technology for preventing people from encountering unsafe water in their home.
In the meantime, there are several precautions consumers could take to improve their home’s water quality.
“Choose plumbing designs that minimize the amount of water and time that water sits still. This should help limit microbial growth and lessen the chance that chemicals leaching from the plumbing exceed unacceptable levels. If you have an existing home, flush the faucet before taking a drink to get rid of the old water. Flushing can help bring in new, fresher water from the building entry point,” Whelton said.