Laundry items that are washed with the same water may contain dangerous bacteria, a new study has found.
The findings could mean more expensive cleaning solutions may be required, potentially making cleaning your clothes a more expensive proposition.
A study of 4,000 washing machines found that those that used a rinse cycle and used a chlorine rinse cycle were more likely to contain bacteria than those that were not.
The bacteria were found to be present in the detergent, soap and water used to wash clothes.
The findings have been published in the journal Environmental Science & Technology.
The study also found that washing machines with a chlorine cycle were most likely to have a pH of 3 or higher, which could potentially affect how the water reacts with the clothes.
“We were interested to know if the pH of a wash cycle was associated with the presence of bacteria,” Dr. Simon Williams, who led the study, said in a statement.
“We also wanted to determine whether these results were specific to washing machines or to detergent that had been used.
To do that we ran a number of tests on each detergent to see how it differed in its pH with respect to each wash cycle.
While the results are not entirely clear-cut, we can’t rule out that some of the washing machine bacteria are being transferred from the washing machines into the washing water,” Williams added.
According to the study authors, this may mean that detergent manufacturers have to make a wash water with a pH higher than 3.
It is also possible that the chlorine cycle is causing the bacteria to survive longer in the water.
“The longer they survive, the more bacteria there are in the wash water,” Dr Williams told the BBC.
“So we know that they may be more likely than other items to make it into the water.”
Williams added that the study showed that detergents should not be used to clean clothes for more than a day at a time.
This may include washing a washing machine for a day or two, as well as washing clothes for a longer period.
He said the study only looked at detergent washing machines and not the products that were sold as laundry detergens.