Halogen’s sensors are the only sensors Certified to NSF61 for safe drinking water exposure. Other sensors require a waste of over 70,000 gallons per year of treated water that must be disposed of. One customer measured 138,000 gallons of waste stream water from his prior  instrument. This water would otherwise be billable at rates of $0.007 to more than $0.01 per gallon.  This is at least $400 per year.