HOUSTON – When you think of wastewater treatment plants, you may not think of medical research. But weekly water samples from 39 different Houston area treatment plants are now helping in the fight against the coronavirus. Researchers compare the wastewater data to the daily positivity rates and then monitor trends across Houston. “The key discovery with this project was that the wastewater signal seems to be ahead of the nasal testing data,” Dr. Maresso said. Health officials said overall the Houston area numbers are going down, but in southwest Houston, the numbers are slightly higher.