CO Plumber cheat sheet

Static pressure conversion: 1 foot of water column = 0.433 psi; 1 psi = 2.31 feet of water column.

Drainage slope: 1/4 inch per foot for pipe 2-1/2 inches and smaller; 1/8 inch per foot for 3-inch and larger horizontal drainage pipe.

Fixture trap seal must be a minimum of 2 inches and a maximum of 4 inches of water depth.

Air gap = unobstructed vertical distance through free atmosphere between the lowest supply opening and the flood level rim; never less than 1 inch and at least twice the effective pipe opening.

Backflow occurs by backsiphonage (negative supply pressure) or backpressure; protection is by air gap, vacuum breaker, or testable backflow preventer.

Excavations 5 feet deep or more require a protective system (slope, shore, or shield); trenches 4 feet or deeper need a ladder within 25 feet of travel.

Confined space entry requires atmospheric testing: oxygen between 19.5% and 23.5%, and no flammable or toxic gas above exposure limits.

DWV water test: 10-foot head of water held for at least 15 minutes with no drop in level; an approved air test may be substituted where allowed.

Copper tube wall thickness: Type K heaviest (green), Type L intermediate (blue), Type M lightest (red); Type M is restricted in some underground and high-pressure uses.

Solder and flux for potable water must be lead-free, meaning not more than 0.2% lead, and labeled as such.

PVC is joined with PVC solvent cement plus listed primer (purple); CPVC requires cement and primer listed for CPVC and is rated for hot water distribution.

PEX is joined only with mechanical insert fittings (copper crimp rings, stainless clamp rings, or compression) and must be protected from sunlight and freezing.

A dielectric union or dielectric nipple is installed between copper and steel or galvanized pipe to break the electrical path and prevent galvanic corrosion.

Support spacing: copper 1-1/4 inch and smaller every 6 feet, 1-1/2 inch and larger every 10 feet; PVC 1/2 to 1 inch every 3 feet, 1-1/4 to 2 inch every 4 feet.

Hubless cast iron soil pipe is joined with a neoprene gasket sleeve compressed by a stainless steel band clamp (no-hub coupling).

Buried pressure pipe needs thrust blocks at bends, tees, and reducers, or restrained joints, to resist the thrust of flowing water.

Minimum sizes: building water service 3/4 inch; fixture supply tube 3/8 inch; building drain 3 inch where the code permits.

Temperature and pressure relief valve opens at 210 degrees F or 150 psi, whichever occurs first, and must be rated to match the heater's input.

T&P discharge must be full size, gravity-flow, without valves or traps, terminate unthreaded no more than 6 inches above the floor or outside above grade.

A water heater in a closed system (check valve, pressure-reducing valve, or backflow preventer) requires an expansion tank or other approved thermal expansion control.

Gas-fired water heaters must be listed as flammable vapor ignition resistant (FVIR) with a sealed burner compartment and flame arrestor.

A sediment trap (drip leg) is required on the gas line at each appliance, downstream of the appliance shutoff valve and as close as practical to the inlet.

Minimum flowing pressure: 8 psi at a fixture outlet; 15 psi for flushometer (flush valve) water closets and urinals.

Water closet clearance: at least 15 inches from bowl centerline to any sidewall and at least 21 inches of clear space in front of the bowl.

Shower control valves must be pressure-balancing or thermostatic mixing type to limit temperature swings and reduce scald risk.

Dishwasher discharge must connect through an air gap or air break; floor drains subject to evaporation need an approved trap primer.

A permit is required before installing, altering, or replacing plumbing piping, fixtures, or water heaters, subject to the exemptions listed in the code.

Rough-in inspection is requested after DWV and water piping are installed and tested, and must occur before the work is covered or concealed.

Final inspection is requested after fixtures are set, appliances are connected, and the system has been tested and is ready for use.

Colorado adopts the International Plumbing Code with state amendments as the Colorado Plumbing Code, administered through the State Plumbing Board.

Testing before inspection: drainage and vent piping with a 10-foot head of water for at least 15 minutes; building sewer tested separately.

The State Plumbing Board, within the Department of Regulatory Agencies, licenses master, journeyman, and residential plumbers.

A master plumber is the licensee authorized to contract for plumbing work, take out permits, and supervise journeymen and apprentices.

Work concealed before inspection may be ordered exposed by the code official so that it can be examined and tested.

The code official may approve materials or methods not specifically named in the code when evidence shows they are equivalent in quality, strength, and safety.