Water Supply Lines & Gas Connectors

Seventy-six supply lines and appliance connectors, from Fluidmaster (51), LSP Products (11), BrassCraft (10), T&S Brass (2), Mountain Plumbing (1) and Pasco (1). By fixture: 33 faucet and sink, 17 toilet, 9 gas, 9 dishwasher, 4 washing machine and 4 ice maker.

Every supply line is three numbers, in this order

A water supply line is described as inlet x outlet x length, and getting the order right is most of the job. The inlet is what threads onto the shutoff valve under the fixture. The outlet is what threads onto the fixture itself. The length is the third number, and it is the one people guess at. A listing that reads 3/8" x 1/2" x 16" means a 3/8" connection at the stop, a 1/2" connection at the faucet, and 16 inches between them.

What COMP, FIP, OD COMP and ballcock actually mean

COMP is compression, and the number is the outside diameter of the tube the nut seats on - 3/8" COMP is the near-universal outlet on a residential angle stop. FIP is female iron pipe, a tapered thread; 1/2" FIP is the standard faucet shank. OD COMP is the same compression nut sized to slip straight over 3/8" tubing with no adapter. Ballcock is the 7/8" nut on a toilet fill valve, and it is the same on every fill valve made in the last forty years, which is why every toilet supply line here ends in 7/8". Match the thread type, not just the number: a 3/8" COMP nut will not seal on a 3/8" FIP thread.

Toilet supply lines

Seventeen toilet connectors, all 7/8" ballcock on the tank side, with 3/8" or 1/2" COMP or FIP at the stop, in 9", 12", 16" and 20". Fluidmaster's PRO1T and PRO4T series are the braided stainless versions; B1T, B3T and B4T are the same lengths in No-Burst. LSP's SWC-112-PP and SWC-116-PP cover 12" and 16". The Mountain Plumbing MT436X/CPB is the outlier - a rigid 20" flat-head riser in polished chrome, for exposed installations where a braided hose would look wrong. Pair these with the stop valves they thread onto and the toilet repair parts on the other end.

Faucet and sink supply lines

The largest group at 33. The common case is 3/8" COMP at the stop and 1/2" FIP at the faucet, which is the PRO1F and B1F series in 9" through 30". When both ends are compression - a stop and a faucet that both take 3/8" tubing - that is the PRO6F, PRO8F, B6F and B8F series. When both ends are FIP, it is PRO4F and B4F. BrassCraft's 1-36A and B8-16A are rigid chrome supply tubes rather than flexible hose, for the same exposed-installation reason as the Mountain riser. A faucet supply line should reach with a gentle curve: one pulled straight and under tension fails at the ferrule, not in the middle.

No-Burst and braided stainless are not the same thing

Fluidmaster sells both and the listings say which. Braided stainless steel is an EPDM rubber core inside a woven stainless jacket - the jacket is what stops the core ballooning. No-Burst is a reinforced polymer construction. Both are rated for potable water and both pass the same standards; the practical difference is that inspectors and property managers generally expect braided stainless on appliance connections, and it is what you want anywhere a failure drains onto drywall.

Dishwasher supply lines

Nine, and they are longer than people expect - 48" to 84" - because the line has to run from the sink base cabinet, behind or under the cabinet wall, to the inlet at the front of the dishwasher. Fluidmaster's B1W and B6W series cover 48" and 60" in 3/8" and 1/2". LSP's MightyFlex KDW-560-PP and KDW-684-PP are 48" and 84" with a 3/8" COMP x MIP end, which is the elbow the dishwasher inlet actually takes. Buy the length that reaches without a coil behind the machine.

Washing machine hoses

Four, in 48", 60" and 72", all 3/4" FGHT - female garden hose thread - on both ends. This is the one connector in the house most worth replacing on a schedule rather than on failure: a burst washing machine hose discharges at full supply pressure into a room with no one in it, and it is a leading cause of residential water damage claims. Braided stainless is the right choice here and it is what all four of these are. Turn the valves off if the machine sits unused for a week.

Ice maker lines and gas connectors

The four ice maker supply lines are Fluidmaster's 12IM series, 1/4" COMP on both ends in 72", 84", 96" and 120" - long, because the run goes from under the sink to behind the refrigerator. The nine gas connectors are a different animal: BrassCraft's CSS series in 1/2" and 3/4" FIP x MIP from 12" to 48", plus two T&S Brass commercial hoses, the HG-2D-36 and the HG-4D-48K with quick disconnect for foodservice equipment. A gas connector is never reused. The flare seat deforms permanently the first time it is tightened, so a connector that comes off an appliance during a move or a repair is replaced, not reinstalled. For rigid runs see flexible gas pipe.

Getting the length right

Measure from the face of the stop valve to the fixture inlet, then add roughly 3 inches. Too short puts the line in tension and loads the ferrule; too long forces a coil that kinks against the cabinet floor. For toilets, 12" covers most standard rough-ins and 20" covers a stop set low or off to one side.

Related

Supply lines are half of a pair - see the angle stops and straight stops they connect to. For the fixtures on the other end, browse centerset faucets, pull-out kitchen faucets and toilet tanks, or the full kitchen and bathroom departments.