Coronavirus and water: what we know and don't know

Bad Dad and I met in a chemistry lab and most of our friends are also in STEM.  I just want to clear up some points of confusion about Coronaviruses (CV) for the lay public.

First off, don't panic if you are among the many that can't find cleaning supplies.  We're running low on TP and cleaning supplies at our house but we still have soap.  Fortunately, you don't need anything fancy and you probably have enough around your house.

Coronaviruses (CV) have a lipid (fatty) envelope and detergents break up their envelope/shell.  Without it, the RNA inside can't force their way into your cells.  Any soap will do.

The American Chemical Society did a great video, Can Soap REALLY Kill the Coronavirus?



It features Professor Palli Thordarson, whose Twitter thread about how we are so certain that soap kills Coronaviruses went viral.

It's well worth 5 minutes, if only to take a trip down memory land about how a HS chemistry teacher's chance remarks led me to take honors chemistry at Berkeley and change my major to chemistry.  Hydrogen bonds got me hooked on chemistry and played a big part in my PhD research.  It's all so great.  I hope you watch it with your kids.

The short answer is that soap is Kryptonite to fatty structures.  Soap, scrubbing and rinsing thoroughly are all you need to do.  Alcohol (if it is strong enough) and oxidizing agents such as bleach, ammonia and hydrogen peroxide will also work.

There are so many chemists on Twitter, sharing what they know and don't know.  It's a little bit hard to parse it all.  On the one hand, one pair of engineering professors say our water supply might not be safe from CV?

Two researchers, Haizhou Liu, an associate professor of chemical and environmental engineering at the University of California, Riverside; and Professor Vincenzo Naddeo, director of the Sanitary Environmental Engineering Division at the University of Salerno, have called for more testing to determine whether water treatment methods are effective in killing SARS-CoV-19 and coronaviruses in general.

On the other hand, another pair of engineering professors, Wigginton and Boehm, tell us our water treatment systems are effective at killing CV and our water supply is safe.

Which is it?

After much reading, and recalling conversations with a friend and chemical engineering professor that does wastewater recycling research, I can tell you all four of them are correct and they actually came to the same conclusion.  Mostly safe, but more research is needed.

If our water system is well maintained (no leaks, no overflows) then our primary and secondary waste water treatment will remove most of the CV in sewage.  It will end up in the biosolids portion, which will be composted at such a high temperatures that it will kill the CV.

The small amount that is in the liquid part, as long as it is undergoes disinfection either with oxidation (chemical sanitization) or ultraviolet light (UV sanitization), should also be safe.  Here's a flow chart (ha ha) of the tertiary and advanced water treatment steps taken at my LA area's plant:

The purple pipe landscaping water sent out to parks and schools is disinfected and should be safe. The industrial water sent to refineries and power plants for cooling is not usually disinfected.  But, it undergoes microfiltration and then reverse osmosis (RO).  Viruses and bacteria are just too big to get through the little holes of the microfilters.  Even the remnants are too big to go through the many layers of the polymer membranes used in reverse osmosis.  If the system is in good working order, the water sent to refineries and power plants and that you see evaporating into the air is safe.

The water that is put into the aquifers through barrier injection wells undergoes microfiltration, RO, aeration, UV disinfection and then gets some minerals (lime) put back in to stabilize it at a neutral pH.  As long as there are no leaks or biofilms, it's perfectly safe.  It's cleaner than the water that is already there.  In fact, it's the purest source of water available to us in Los Angeles.

Biofilms is the problem that Liu and Naddeo alluded to.  They are incredibly tenacious.  If they form in your pipes, they are really hard to remove.  They also form in water recycling plants.  That's one reason why they need to be taken off-line for periodic maintenance.  They can also form in household plumbing.  Most biofilms are harmless (and I hope the one in my toilet is one of the harmless ones.)  Legionaire's disease was able to spread in hotels and on ships through biofilms in shower heads. What we don't know is if CV can incorporate into biofilms.

SARs spread through Amoy Gardens, an older Hong Kong apartment building through a vulnerability in sewage plumbing.

Recent investigations into the March 2003 outbreak of SARS in Hong Kong have concluded that environmental factors played an important role in the transmission of the disease. These studies have focused on a particular outbreak event, the rapid spread of SARS throughout Amoy Gardens, a large, private apartment complex. They have demonstrated that, unlike a typical viral outbreak that is spread through person-to-person contact, the SARS virus in this case was spread primarily through the air. High concentrations of viral aerosols in building plumbing were drawn into apartment bathrooms through floor drains. The initial exposures occurred in these bathrooms. The virus-laden air was then transported by prevailing winds to adjacent buildings at Amoy Gardens, where additional exposures occurred. This article reviews the results of the investigations and provides recommendations for maintenance and other measures that building owners can take to help prevent environmental transmission of SARS and other flulike viruses in their buildings.

Los Angeles' housing stock skews old.  This is the stuff I worry about.  How well designed, built and maintained is all that old plumbing?  How do we come up with the money and will to take inventory and ensure everyone is safe?  This crisis has exposed so many of our society's cracks.

The COVID-19 Waterblog is available for all you water nerds out there. That's how I learned about Professor Krista Wigginton's research in SARs and CV.  Survivability, Partitioning, and Recovery of Enveloped Viruses in Untreated Municipal Wastewater is fascinating reading.

The American Chemical Society has put together a special virtual issue: Overview of Research on the Fate and Behavior of Enveloped Viruses in the Environment.  It combines older, peer-reviewed research with our best educated guesses based on emerging evidence.

So there's stuff we don't know.  And stuff we do know.  Combining those, we have a good idea of how we should protect ourselves.  Fortunately, even though COVID-19 persists and is detectable in raw sewage for many hours, it appears to be less biologically active in water than SARS.  It's more easily spread in human-to-human contact due to asymptomatic people spreading it around.

COVID-19's ability to spread from person to person is scary enough.  But, I'm not worried about the sewage line that runs down the middle of the street.  Our area pays parcel taxes for water systems in addition to the water bill.  That provides a sustaining source of money to maintain and upgrade systems.  In the time that I have lived here, I've seen upgrades/replacements/repairs on stormwater and sewage systems.  In fact, a large chunk of the sewage pipe on my block was dug out and replaced.

I also know that deferred maintenance is the norm in most parts of the country.  Flint is not unusual. Continuous monitoring and maintenance is essential, but it requires a continuous budget.

Since I became the Natural Resources chair for the League of Women Voters of Los Angeles County, I began writing a monthly roundup of local environmental news-both the science and the policy.  Half of the March newsletter (written in February) was about the safety and affordability of water in LA county.  Are you interested in reading about it here on the blog as well?

What kinds of things do you want to read?