Tap (Valve): Definition & Technical Guide
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A tap is a valve mechanism that controls the release of water from a plumbing supply line at a point of use, such as a sink, bathtub, or outdoor hose bib. Taps operate by opening and closing a flow passage using a handle, lever, or sensor, allowing the user to start, stop, and regulate the flow rate and temperature of water delivered to a fixture.
Valve Element Types: Compression Washer, Ball, Cartridge & Ceramic Disc
The term “tap” is used interchangeably with “faucet” in American plumbing, though “tap” more precisely refers to the valve mechanism itself rather than the complete fixture assembly. A tap converts the pressurized water in the supply line into a controlled stream by modulating an internal valve element, which may be a compression washer, ceramic disc, ball, or cartridge.
When a tap handle turns or lifts, the internal valve element moves away from the valve seat, creating an opening through which pressurized water flows. The degree of opening determines the flow rate. In single-handle taps, the same mechanism also blends hot and cold water supplies by adjusting the ratio of each input.
Municipal water pressure typically ranges from 40 to 80 PSI at the service entrance. The tap must regulate this pressure into a usable stream without creating excessive noise, vibration, or water hammer. Properly functioning tap valves reduce flow smoothly and seat completely when closed, eliminating drips that waste water and increase utility bills.
Compression, Ball, Cartridge & Ceramic Disc Tap Configurations
Compression taps use a rubber washer pressed against a brass seat by a threaded stem. Turning the handle tightens or loosens the washer against the seat. These are the oldest design and the most prone to dripping as washers wear.
Ball taps use a slotted metal or plastic ball that rotates to align openings with the hot and cold supply ports. These are common in single-handle kitchen faucets.
Cartridge taps contain a movable cartridge with channels that align to open or close flow. Both single-handle and double-handle versions exist. Cartridge replacement restores a worn tap to like-new condition.
Ceramic disc taps use two polished ceramic plates that slide against each other. These are the most durable tap type, resisting wear for hundreds of thousands of cycles without developing drips.
Faucet Cartridge Replacement, Backflow Prevention & Fixture Services
Tap repair and replacement is one of the most common residential plumbing service calls. A dripping tap wastes up to 3,000 gallons of water per year according to the EPA. Bonded Plumbworks’ faucet and fixture services include tap cartridge replacement, valve seat reconditioning, and complete faucet installation.
Outdoor taps, known as hose bibs or sillcocks, require frost-free designs in climates with freezing risk, though in warm-climate regions the primary concern is backflow prevention. Bonded Plumbworks installs vacuum breaker attachments on outdoor taps to comply with backflow prevention requirements and protect the potable water supply.
EPA WaterSense, ASME A112.18.1 & NSF/ANSI 61 Lead-Free Requirements
The EPA WaterSense program certifies taps that use no more than 1.5 GPM at 60 PSI, compared to the federal maximum of 2.2 GPM. The State building codes reference ASME A112.18.1/CSA B125.1 for faucet and tap performance standards, including flow rate, durability testing, and lead content limits. The Safe Drinking Water Act requires all taps used for potable water to comply with NSF/ANSI 61 for lead-free materials (less than 0.25 percent weighted average lead content).
Moen, Delta Diamond Seal, Kohler Purist & Pfister Pforever Product Lines
Moen manufactures cartridge-based taps with the 1225 and 1222 cartridge system for single-handle operation. Delta produces the Diamond Seal Technology series with ceramic disc valves. Kohler offers the Purist line with precision ceramic disc valve technology. Pfister manufactures Pforever Seal taps with a lifetime drip-free guarantee.