08Hoses, lines and seals · thread first
A 3/8-inch supply line is not a 1/2-inch one with a different nut.
Braided supply line in 3/8 compression or 1/2 FIP, washer fill hoses, and O-rings sold one at a time by dash number. Lines run $8 to $22, single O-rings about $0.40, kits $12 to $28. Indicative figures; the counter confirms after it reads the thread.
Measuring thread OD · not the nut
RK-08A
Braided supply line, 3/8 compression or 1/2 FIP, cut to the length you need
A supply line runs from the angle stop on the wall to the faucet or the toilet fill valve. Ours are stainless steel braid over a PEX or EPDM core, with crimped brass or plated ferrules. The two ends are what matter. On the stop side it is almost always a 3/8 compression nut. On the fixture side it is 1/2 FIP for most faucets, 3/8 compression for some, and 7/8 ballcock for a toilet.
People bring in a nut and say "it's half inch." The nut is wider than the thread it fits, so a 3/8 compression nut reads close to 5/8 on a ruler. Measure the outside diameter of the male thread on the stop instead, or bring the old line. We hold it against a thread gauge in about ten seconds.
Length runs 12, 16, 20 and 24 inches on the shelf, with 30 and 36 for kitchen islands. Buy the shortest one that reaches without a tight bend. A braided line kinked into a loop under a sink is the one that bursts on a Sunday.
| Connection | Where you find it | Thread OD, approx. | Lengths |
|---|---|---|---|
| 3/8″ compression | Angle stop outlet, some faucet tails | ≈ 0.56″ | 12–36″ |
| 1/2″ FIP | Faucet shank, older lav faucets | ≈ 0.84″ | 12–30″ |
| 7/8″ ballcock | Toilet fill valve shank | ≈ 0.88″ | 12–20″ |
| 1/2″ compression | Some older stops and ice-maker tees | ≈ 0.69″ | On request |
$8–$22 per line · indicative, confirmed on reply
Washer fill hoses: change them on a calendar, not on a leak
Rubber washer hoses fail at the crimp, usually without warning, and a 3/4 garden hose thread at house pressure moves several gallons a minute. Braided replacements in 4, 5 and 6 foot lengths with a 90-degree elbow at the machine end are on the shelf. Five years is the usual swap interval printed by the hose makers. If the old washer at the nut has gone flat and hard, replace the hose, not just the washer.
RK-08B · O-ring assortment and singles
O-rings by dash number, in nitrile or silicone, one at a time
An O-ring has three numbers that count: inside diameter, cross-section and material. The AS568 dash number captures the first two. A 2-018 is 0.739 inch ID by 0.070 inch section; a 2-112 is 0.487 by 0.103. Two rings with the same ID and a different section will both slide on, and only one will seal.
Nitrile (Buna-N, 70 durometer) is the default for cold water and most appliance couplings. Silicone handles hot water and coffee makers better but tears if you roll it over a sharp thread. We cut nothing to size. If a ring is not on the AS568 chart, we say so and point you to a supplier who carries metric.
Bring the old ring in a bag, even if it is flattened. We measure the groove too when you bring the fitting, because a squashed ring reads small.
| Dash no. | ID | Section | Typical use |
|---|---|---|---|
| 2-010 | 0.239″ | 0.070″ | Cartridge stem, small valves |
| 2-015 | 0.551″ | 0.070″ | Faucet spout body |
| 2-018 | 0.739″ | 0.070″ | Filter housings, spout swivels |
| 2-112 | 0.487″ | 0.103″ | Diverters, inlet valve couplings |
| 2-214 | 0.984″ | 0.139″ | Pump housings, larger caps |
$0.40 each · kits $12–$28 indicative, confirmed on reply
AS568 · nitrile 70A · silicone
→From leak to fitting
Four steps from the drip to the right fitting
- Shut the stop and take the old part off
Keep the line or the ring. A photo of both ends with a coin for scale also works.
You · before you send anything - We read the thread
Thread gauge and caliper on the male end. Dash number from the ring and, if you brought it, the groove.
Counter · a few minutes - Price confirmed
Shelf stock leaves with you. Odd lengths or metric rings get a confirmed number before we order.
Counter · on reply - Hand-tight plus a quarter
We tell you how far to turn it. Overtightened compression nuts crack the ferrule and leak worse than before.
Counter · at handover
?Thread questions
What people get wrong about lines and rings
Do I need plumber's tape on a compression fitting?
No. A compression fitting seals on the ferrule, not the thread. Tape on it can keep the nut from seating. Tape belongs on tapered pipe threads, and even there a supply line with a rubber cone washer does not need it.
Can I just buy a kit of 200 O-rings?
You can, and for a workshop it makes sense. For one dripping spout, buy the two rings it takes. The kit has the right section in maybe four sizes.
Who should not buy here?
Gas appliance connectors are not sold over this counter. Neither are hydraulic or high-pressure air fittings. If the line feeds a gas range or dryer, that connection goes to a licensed tech.
Ask about this part
- The old line, both ends attached
- The O-ring in a bag, flattened or not
- Distance from stop to fixture, in inches