Can You Reuse Sous Vide Water?

Sous vide machines have been popular in professional kitchens for years, but they're slowly making their way into home kitchens — and not just because this method makes the best thick-cut bacon. Cooking sous vide calls for slow cooking vacuum-sealed food at low temperatures in a large amount of water. This method is entirely temperature-controlled and takes the guesswork out of cooking. You can be precise in cooking food to perfect doneness without any cutting, poking, or prodding, all while preserving moisture and keeping flavor consistent. 

The sous vide method of cooking has a lot of perks, but compared to other cooking techniques, it's not the most sustainable. Namely, it wastes a lot of water. Instead of drawing fresh water from the tap every time you break out this tool, can you reuse sous vide water instead? There's a lot of debate around the topic, so we asked Bryan Quoc Le, food science consultant, to get some insight. 

The water used for sous vide cooking never touches the food, which is inside food-grade vacuum-sealed bags. Still, due to food safety concerns, Le says it's only okay to reuse the water on the same day. "Although many people will reuse the water for days or even weeks, this is a big hazard and is imprudent, since even large sous vide vessels use less water than a typical shower," he says.  

Even after only one use, the risks of reusing the water remain. For this reason, Bryan Quoc Le encourages chefs to proceed with caution. "Anytime there is standing water, there is the risk of microorganisms growing in it. One such concern is the formation of biofilms, which are slimy layers of bacteria that form in watery environments, are extremely difficult to remove, and are more heat resistant than free-floating bacterial cells." Some chefs might feel safe since the food is in a bag, but that's not always enough. Le explains that "although the food is sealed within a bag, the bacteria from the water are still on the outside of the bag, which can spread onto the food once it is opened."

Especially if you're using a recipe that calls for lower temperatures, consider using fresh water for peace of mind. "I would like to emphasize that the heat resistance of some bacteria is an important point, since sous vide that is performed at lower temperatures would not kill any bacteria present in the water; just because the time and temperature cooks food does not mean that it kills bacteria," Le notes.

If you do decide to reuse water for sous vide, it's important to store the water correctly to avoid any issues. For starters, always keep the water in a food storage bin with a lid, such as Komax's airtight container. Mold can still grow in the water between uses and makes the water cloudy. If this is the case, toss it, but don't use that as your only metric. "Many people who reuse the water will use the cloudiness or color of the water as an indicator to discard it, but at that point, it is already full of bacteria, since clean water is always clear," Bryan Quoc Le says. 

Lastly, if your vacuum-sealed bag becomes punctured and water seeps in, you should throw the food and water away. You can reuse sous vide water because it does not touch the food, but if your reused water happens to seep inside, the whole meal is compromised. After you've reused sous vide water once, or any unsavory changes to the look or smell of the water become noticeable, it's time to pour it down the sink and start fresh.