The Bright Dyes Dye Tracer Liquid Blue is a blue liquid dye used to detect leaks in plumbing and HVAC systems. It contains a concentrated blue dye that mixes with water. When added to a system, any leaks will release blue-dyed water for easy leak detection. This product is rated for use in all potable water systems and is safe for PVC, CPVC, copper and other common plumbing materials. It comes in a 16 oz plastic bottle with an easy pour spout that allows controlled dispensing into systems. This professional-grade leak detector provides an effective method to pinpoint leaks.