HOUSTON, Texas (KTRK) -- For more than a year, the city of Houston's health department has been testing wastewater to get a better idea of how fast the virus is spreading and what is to come.
Now, the Chief Medical Officer for the City of Houston Dr. David E. Persse said the levels of the virus have more than tripled the benchmark taken more than a year ago.
During a news briefing Wednesday, Persse explained the use of wastewater has helped predict what the situation would be like at least two weeks ahead.
"The wastewater predicts what's about to happen two to four weeks ahead of time," Persse said. "We saw the value of the wastewater dropping, before we saw the positivity rate dropping, before we saw the hospitalizations drop."
It's a method Persse said is "extremely reliable."
Wastewater plants are seen all over Houston, 39 treatment facilities to be exact. They're responsible for treating more than 250 million gallons of wastewater per day and are connected by 6,100 miles of sewer lines.
This is not the first time health experts have looked at the wastewater levels to look ahead at what's to come.
Earlier this year in March, as the U.K. variant was spreading, Persse said the variant was found "in large amounts" and is spreading through the city fast.
At the time, said on Feb. 8, the U.K. variant was found in 21 of the city's 39 wastewater treatment plants. Fourteen days later, on Feb. 22, he said the variant was found in 31 out of 39 treatment plants.
"Nineteen percent of all the virus that has been tested in the wastewater across the city has the genome that's consistent with the U.K. variant," said Persse. "That does not mean that 19% of the people in Houston are infected with the U.K. variant ... it does not mean that. We know that there is a fairly large amount of the U.K. variant in our community and it is spreading."
WATCH: Dr. David Persse on the wastewater detection of COVID spread
So with delta now showing to be the dominant variant, what do the current wastewater levels look like?
In June of this year, without peak, the levels were at 250%. Two weeks ago, levels were at 231% and last week, the levels were at 370%, according to Persse.
According to a tweet from the health department, a graphic also showed that the current wastewater is 320% more than the benchmark level of July 6, 2020.
"The virus is spreading rapidly. It's spreading everywhere. It's spreading very intensely," Persse said on Wednesday. "We are at a level of virus in the wastewater that we have never seen before."
Given those numbers, Persse said the wastewater predicts what we'll see in the positivity rates in two weeks, which also predicts what we will see in hospitalizations.
"I can pretty much guarantee you it's only going to worse over the next four weeks," said Persse, who also urged Houstonians to get vaccinated.