22:23

Sam Levin here, taking over our ongoing live coverage of tropical storm Harvey, which now has a confirmed death toll of 31 people, a number expected to rise.

The AP is now reporting on a Texas A&M University analysis of Houston floodwater samples, showing E coli levels that are 125 times higher than is considered safe for swimming. Walking through the floodwater could lead to infections and other problems, said Terry Gentry, an associate professor in the university’s department of soil and crop sciences.

A test in a suburb northwest of Houston showed bacteria levels 15 times above the safe level, according to the AP. Here’s an ABC News segment with more detail:

The Environmental Protection Agency and Texas Commission on Environmental Quality have also just released a statement noting that there can be “releases of wastewater from sanitary sewers occur during major flood events”, adding: