Liquid oxygen — often used to treat tap water — is in short supply because it's needed for hospitalized COVID-19 patients.
WUSF's Daylina Miller spoke with Tampa Bay Water Acting Chief Operating Officer Jack Thornburgh about what that means for the area's water supply.
Daylina Miller: Cities like Tampa and Orlando are asking residents to cut down on unnecessary water use because the hospitals need liquid oxygen for COVID-19 patients. What is liquid oxygen and how's it used for treating water?
Jack Thornburgh: "Liquid oxygen is used in our plant to generate ozone. And ozone is a very powerful disinfectant that has a very short lifespan. So it can be used in places where normally chlorine would be used or some people call, you know, bleach, sodium hypochlorite. But the benefit of it is it has such a short lifespan and it's very powerful, and it doesn't combine with other compounds that make it not good for human consumption. So it is a preferable disinfectant."
Tampa Bay water announced recently that liquid oxygen would be replaced temporarily by bleach for treatment. But drinking water would still be meeting local, state and federal regulations. Can you tell us more about that?
"The groundwater plant is more amenable to being converted to chlorine, because the water that goes into that plant is pretty clean. Disinfecting there and treating the other compounds with bleach is not too big of a deal. Our other plant is a surface water treatment plant. And we treat river water; the pollutants that come in that water are a lot more challenging to treat. And those are the ones that can have some detrimental effects if they combine with chlorine before you remove them from the water. So we normally remove all of those compounds at our surface water plant with either clarification or the ozonation that we're using or filters. Before we add any chlorine to that water."
As COVID cases continue to rise, there may be a greater need for liquid oxygen, what if you can't use it at all anymore?
"We have a lot of resiliency built into the design of our system. So we have three sources. Normally, we have the groundwater in multiple locations, we have the surface water that I just discussed, we also have desalinated water that we can access most of the time. So because of that, we're able to shift our supplies around and access water more where we need it. Now our surface water is generally supply almost half of the water that we make for our system. It's not an easy change, but our system is able to handle it. It's just a matter of us having to reconfigure the entire system."
COVID cases are rising in other parts of the state, not just Central Florida. So why aren't we seeing more municipalities issuing warnings about water usage?
"The Tampa Bay area is one of the larger users of ozone for water treatment. You've already heard from like Orlando utilities put out an announcement. This is a very rapidly changing issue. And you may be hearing more from other people. But we are really more dependent on the liquid oxygen in this area. So that's why you're hearing more from us. We use chlorine instead of ozone in in many places in our system already. The ozone is just preferable, where we're treating things like the surface water because that river water is much more treatable with ozone than it is with the chlorine."
Is it possible that Tampa Bay water would stop using liquid oxygen altogether at some point?
"In the long term, I think that we wouldn't be able to change our system to not use any liquid oxygen at all."
With the pandemic being far from over, what's the future look like for Tampa Bay Water?
"We're going to switch to the sources that are not using liquid oxygen. We'll continue to use our surface water plan as long as we can get liquid oxygen but if we run out, we will just switch to the other sources related to groundwater and such. Right now we're going to have to lean a little bit more on the groundwater. So our surface water plant in our DSL plant were designed to help reduce our reliance on the groundwater, but we still have it available to us so we're gonna switch to that for the time being and as soon as this liquid oxygen shortage is over, we'll be putting putting ourselves back into a mode where we can conserve more of the groundwater and use other sources."
