Is Re-Boiling Old Water Safe? ByStephanie Holmes, 04/26/2017 Gourmandize shares Share on Facebook Share on Twitter Pin it Share on WhatsApp Share on Google+ 4/4 Previous Next What about day-old water? Seeing as most water boilers have been upgraded in recent years, there are typically no pollutants found within 24 hours of leftover water. So you can probably use yesterday's water, but if it's been several days, it's advised to replace it. More steaming articles Past Contests International Team Christmas Countdown - 24 Days to go! Chef Tips and Tricks 8 Mistakes That Everybody Makes With Pasta Do you put the pasta in without waiting for the water to boil? Add oil? Forget the salt?