Haizhou Liu of UC Riverside's department of chemical and environmental engineering

Already under siege by cost overruns and litigious contractors, San Diego mayor Kevin Faulconer's $1.4 billion plan to turn the city's sewage into drinkable water faces new doubts and questions of increased costs brought on by the global coronavirus pandemic

"Regulatory guidelines for virus removal in potable reuse systems need additional review for possible more stringent requirements in the event of a coronavirus outbreak," says an April 2 editorial in the journal Environmental Science and Water Technology, co-authored by Haizhou Liu of UC Riverside's department of chemical and environmental engineering.

Co-author Vincenzo Naddeo of the University of Salerno's sanitary environmental engineering division, department of civil engineering

"For example, the state of California currently requires a 12-log removal of viruses during the entire indirect potable treatment train."

But that may not be enough in the face of pandemic onslaughts by newly evolved viruses, say Liu and co-author Vincenzo Naddeo of the University of Salerno's sanitary environmental engineering division, department of civil engineering.

"Additional log-removal credit may be needed to protect public water systems in light of a virus outbreak," per the paper. "Preferential requirements for different viruses may be needed."

"Another important research need is a better understanding of the efficacy of emerging disinfection technologies for coronavirus inactivation, especially treatment steps that are integrated into potable water reuse."

Yet one more potentially expensive challenge in the age of Covid-19, according to Lieu and Naddeo, is to " develop new or upgrade existing water and wastewater treatment infrastructure for hot-spots that possibly receive coronavirus from sources including hospitals, community clinics and nursing homes."

Long controversial, the mayor's toilet-to-tap sewage reuse plan swept through city council after sponsors agreed to bar non-union contractors from bidding on much of the job, gaining the backing of council Democrats.

The local Associated General Contractors chapter subsequently sued, arguing that special state legislation to prevent non-union contractors from working on state-financed portions of the project was illegal.

Authored by Assembly Democrat Todd Gloria, a current candidate for mayor, and Toni Atkins, state senate pro-tem president, the fate of the bill is before a superior court judge, whose ruling is widely expected to undergo appeal regardless of the decision.

The legal wrangling is likely to add to the project's timeline and cost, which threatens to go sky-high in the face of new treatment requirements brought on by the Covid-19 crisis, which itself is spawning more varieties of disease with which to contend, Liu and Naddeo note.

"As a preventative measure against the coronavirus outbreak, the public is significantly increasing the use of bactericides, virucides, and disinfectants to prevent a possible infection and is limiting travel and activities

"This behavior affects our lifestyle and the economy, but from an environmental point of view it will increase the environmental presence of antibiotic-resistant bacteria."