How much water are your trap primers wasting?
Compare annual water usage, cost, and environmental impact of traditional trap primer systems against Green Drain waterless trap seals. Adjust the inputs below to match your facility.
Configure Your Trap Primer Systems
Enter the details for each trap primer type in your facility. Leave inputs at their defaults for a typical comparison, or adjust to match your specific setup.
Continuous Flow Primer
Systems that continuously flow water to maintain trap seals.
Pressure Drop Activated Primer
Activate based on pressure changes in the water supply line.
Flush Valve Operated Primer
Divert a small amount of water from flush valves to maintain trap seals.
Electronic Trap Primer
Electronically controlled systems that discharge water on a set schedule.
Results: Annual Comparison
| System | Annual Water (gal) | Annual Cost | CO₂ (lbs) | Energy (kWh) |
|---|
Includes water + sewer charges. Check your utility bill or use $10 as a national commercial average.
Why Trap Primers Waste Water
Every floor drain in a commercial building relies on a P-trap – a U-shaped pipe section that holds water to create a seal against sewer gas, odors, and pests. When drains are not used regularly, the water in the P-trap evaporates, breaking the seal and allowing harmful gases to enter occupied spaces.
Trap primers were designed to solve this problem by periodically or continuously delivering water to the drain to replenish the trap seal. While effective at maintaining the seal, they come with significant drawbacks:
The Water Cost Adds Up
A single continuous flow trap primer running at 0.5 GPM for 8 hours per day consumes over 87,600 gallons of water per year. Multiply that across dozens of drains in a commercial facility, and the annual water waste becomes substantial – often tens of thousands of dollars in water and sewer charges alone.
Mechanical Complexity
Trap primers require water supply connections, distribution piping, pressure regulators, and in many cases electrical connections. Each component is a potential point of failure. When a trap primer fails, the P-trap dries out and the building loses its sewer gas protection – the very problem the system was designed to prevent.
The Green Drain Alternative
Green Drain replaces the water-dependent trap primer approach with a mechanical, waterless solution. A one-way silicone valve sits inside the drain pipe, allowing water to flow through normally while sealing shut against backflow of sewer gas, odors, and pests. Because the seal is physical rather than water-based, it works whether the drain is used daily or sits idle for months – with zero water consumption.
This means every gallon shown in the calculator above is water your facility would save by switching to Green Drain. No water supply connections, no distribution piping, no electricity, and no ongoing water cost.
Understanding the four types of trap primers
Not all trap primers work the same way. Each type uses a different mechanism to deliver water to floor drain traps, and the water consumption varies significantly between them. Here is how each system works and why it uses the amount of water shown in the calculator above.
Continuous Flow Primers
Highest water consumption
Continuous flow primers work by maintaining a constant, low-volume stream of water to the drain trap. They connect directly to the building's water supply and deliver a steady flow, typically between 0.25 and 1.0 GPM, throughout operating hours.
While simple and reliable, they are the most water-intensive option. Even at a modest 0.5 GPM running 8 hours a day, a single unit consumes over 87,600 gallons per year. Facilities with dozens of drains can waste hundreds of thousands of gallons annually. These systems are commonly found in older buildings where they were specified before more efficient alternatives became available.
Common applications: Older commercial buildings, hospitals, schools, and industrial facilities with infrequently used floor drains.
Pressure Drop Activated Primers
Moderate water consumption
Pressure drop activated primers detect changes in water pressure within the building's supply piping. When a fixture is used elsewhere in the building (a toilet flush, a faucet opening), the resulting pressure drop triggers the primer to release a measured amount of water to the drain trap.
These are more efficient than continuous flow systems because they only deliver water when triggered. However, in busy buildings with frequent fixture use, the activations add up quickly. At 12 activations per day with 0.5 gallons per activation across 10 units, the annual consumption reaches nearly 22,000 gallons. They also require careful calibration and can fail silently if the pressure sensing mechanism degrades.
Common applications: Commercial office buildings, retail spaces, and facilities with moderate fixture usage patterns.
Flush Valve Operated Primers
Low to moderate water consumption
Flush valve operated primers tap into the water supply of nearby flush valve toilets or urinals. Each time the fixture is flushed, a small amount of water is diverted from the flush cycle to the floor drain trap. The diverted volume is typically small, around 0.1 gallons per flush.
While individually efficient per activation, these systems depend entirely on fixture usage. In high-traffic restrooms, the cumulative water diversion is significant. In low-traffic areas, the opposite problem arises: the trap does not receive enough water and can dry out. They also add complexity to the flush valve assembly and require a dedicated distribution line to each drain location.
Common applications: Restroom-adjacent floor drains in airports, stadiums, convention centers, and other high-traffic facilities.
Electronic Trap Primers
Lowest water consumption among primers
Electronic trap primers use a solenoid valve controlled by a timer or building management system to deliver precise, scheduled doses of water to drain traps. They are programmable, allowing facility managers to set the exact volume and frequency of each discharge cycle.
These are the most efficient traditional primer type, using as little as 0.25 gallons per discharge at intervals as infrequent as every 4 hours. However, they require both a water supply connection and an electrical connection, making installation more complex and costly. They are also dependent on power, so a building outage means trap protection stops. Battery backup units exist but add further complexity and cost.
Common applications: New construction, healthcare facilities, data centers, and buildings with building management system integration.
Green Drain: The Waterless Alternative
Zero water consumption
Green Drain takes a fundamentally different approach. Instead of adding water to maintain a P-trap seal, it replaces the water seal with a one-way silicone valve that physically blocks sewer gas, odors, and pests. Water flows through normally when present, and the valve seals closed when the drain is dry.
This eliminates the need for water supply connections, distribution piping, electrical connections, timers, solenoid valves, and pressure regulators. There are no moving mechanical parts to fail, no calibration to maintain, and no water to consume. The device drops into the existing drain opening in under 60 seconds with no tools required.
Every gallon shown in the calculator above represents water your facility would save by switching to Green Drain. For most facilities, the product pays for itself within the first year through water savings alone.
Frequently Asked Questions
What is a trap primer?
A trap primer is a plumbing device that adds water to floor drain traps to prevent the water seal from evaporating. When a P-trap dries out, sewer gases, odors, and pests can enter the building through the drain opening. Traditional trap primers solve this by periodically or continuously sending water to the drain, but this approach consumes significant amounts of water over time. Green Drain eliminates the need for trap primers entirely by using a waterless, one-way silicone seal that blocks sewer gas regardless of water levels in the trap.
How accurate is this calculator?
This calculator provides estimates based on the inputs you provide and standard operating assumptions. Actual water usage may vary depending on water pressure, system age, maintenance schedules, and local conditions. The default values represent typical installations based on industry data. For a detailed assessment of your specific facility, contact our team for a customized analysis.
How does Green Drain eliminate water usage?
Green Drain uses a patented one-way silicone valve that sits inside the drain pipe. The flexible silicone flaps allow water to flow down through the drain normally but seal closed when there is no flow, creating an airtight barrier against sewer gas, odors, and pests. Because the seal is mechanical rather than water-based, it works indefinitely without any water input – eliminating trap primer water usage entirely.
What is ASSE 1072?
ASSE 1072 is the performance standard published by the American Society of Sanitary Engineering for pressurized flushing devices used as trap seal primers. It establishes testing requirements and performance criteria for devices that maintain water seals in floor drain traps. Green Drain is listed to ASSE 1072, confirming it meets the standard's requirements for trap seal protection – without requiring a water supply connection.
Ready to eliminate trap primer water waste?
Green Drain replaces water-dependent trap primers with a simple, waterless solution that drops into your existing drains. Request a quote for your facility today.