Quick Answer: A gas sediment trap (also called a drip leg) is a simple tee-and-capped-nipple fitting that both the IFGC and NFPA 54 require on nearly every gas-fired appliance, including tankless water heaters, to catch pipe debris before it reaches the unit’s gas valve and burner. If you’re plumbing a new gas line and don’t yet have a shutoff valve installed, the Webstone H-22443-24-FP (about $85–$95) bundles a full-port gas ball valve, the trap tee, and a 24-inch flex connector in one kit. If you already have a shutoff valve and just need the code-required trap fitting itself, the LDR Industries 6092500 (about $10–$15, 1/2-inch) or the EasyFlex EFG-TP-034 (about $10–$12, 3/4-inch) covers it for a fraction of the price.
Search “tankless water heater installation checklist” and most guides mention gas line sizing, venting, and condensate drainage — and skip the sediment trap entirely, even though it’s one of the few components a gas inspector will specifically fail an install over. It’s a five-dollar fitting that gets left out because it’s small, cheap, and easy to assume the installer already accounted for.
Why code requires this, and what it actually does
A tankless heater’s burner fires on demand, drawing gas through orifices sized to a tight tolerance. Any loose debris in the supply line — pipe cuttings left over from threading, rust flakes, dried thread sealant — has a direct path to those orifices and the gas valve’s internal passageways if nothing catches it first. Per the IFGC and NFPA 54, a sediment trap is required on gas utilization equipment specifically to collect that debris before it can reach those small passageways, with the code text describing it as a tee fitting with a capped nipple installed in the tee’s bottom branch, positioned downstream of the equipment shutoff valve and as close to the appliance as practical.
The exception list is short and doesn’t include water heaters: ranges, illuminating appliances, clothes dryers, and outdoor grills are the equipment types NFPA 54 exempts, precisely because their listed construction already integrates an equivalent trap or doesn’t face the same risk profile. A gas tankless water heater has no such exemption.
Sediment trap vs. drip leg — same fitting, different job
The two terms get used interchangeably at the counter of most plumbing supply stores, and the physical fitting — a tee with a capped nipple hanging off the bottom — is often identical. Technically, a drip leg sits at the gas line’s point of entry into the building and is meant to catch liquid condensate out of “wet” gas, required only when the local utility specifies it. The sediment trap that matters for a tankless install sits downstream, right before the appliance, and catches solid particulate rather than liquid. In practice, plumbing supply catalogs and installers use “sediment trap” and “drip leg” for the same appliance-side fitting — this guide follows that common usage.
3/4-inch vs. 1/2-inch: match your gas line size
| Product | Type | Size | Includes shutoff valve? | Price |
|---|---|---|---|---|
| Webstone H-22443-24-FP | All-in-one kit | 3/4" | Yes — full-port gas ball valve | ~$85-$95 |
| LDR Industries 6092500 | Standalone trap | 1/2" | No | ~$10-$15 |
| EasyFlex EFG-TP-034 | Standalone trap | 3/4" | No | ~$10-$12 |
Our gas-line sizing guide covers why most flagship residential gas tankless units land on a 3/4-inch line — the sediment trap has to match that same diameter, not the unit’s BTU rating directly.
1. Webstone H-22443-24-FP — Best All-in-One Kit
Webstone H-22443-24-FP Gas Sediment Trap Kit
- Bundles the three things a new gas tankless install typically needs at the appliance connection — a full-port shutoff valve, the code-required sediment trap tee, and a flexible connector — into one part number instead of three separate trips to the fitting aisle.
- The full-port ball valve doesn't restrict gas flow when fully open, the same design logic the site's isolation-valve-kit roundup uses on the water side — a reduced-port valve can measurably choke flow on a unit already running near its rated BTU input.
- Webstone also sells a 1/2-inch version (H-22442-24-FP) with the identical kit contents scaled down for a shorter or smaller-diameter run.
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This is the pick if you’re plumbing a new gas connection from scratch and don’t already have a shutoff valve at the appliance — one part number covers the whole code-required assembly.
2. LDR Industries 6092500 — Best Standalone Trap (1/2”)
LDR Industries 6092500 Sediment Trap for Water Heater
- Covers just the code-required fitting — a tee, a nipple, and a cap — for anyone who already has a shutoff valve installed and only needs the trap itself, not a full valve kit.
- Sized for 1/2-inch gas lines, which our gas-line sizing guide notes still applies on some flagship units under Rinnai's TB-111 bulletin when the run is short and supply pressure is high enough.
- At roughly a tenth the cost of the all-in-one kit, this is the right buy any time the actual gap in your install is the trap fitting alone, not a missing shutoff valve.
The pick if your install already has a shutoff valve and your gas line runs 1/2-inch.
3. EasyFlex EFG-TP-034 — Best Standalone Trap (3/4”)
EasyFlex EFG-TP-034 Gas Sediment Trap (Drip Leg)
- Same role as the LDR trap above — a standalone fitting, no valve included — sized for the more common 3/4-inch line most flagship gas tankless units land on.
- EasyFlex also sells the identical part in 1/2-inch (EFG-TP-012) if your run turns out to be sized smaller.
- Zinc-plated steel construction is standard for this fitting type and matches the material most inspectors expect to see on a sediment trap, versus a mismatched brass or copper substitute.
The pick if your install already has a shutoff valve and your gas line runs 3/4-inch — the size most flagship residential units need.
How to choose
- New gas connection, no shutoff valve installed yet: the Webstone H-22443-24-FP (3/4”) or its 1/2-inch sibling H-22442-24-FP bundles the valve, trap, and flex line in one kit.
- Shutoff valve already in place, 1/2-inch line: the LDR Industries 6092500 covers just the trap fitting for a fraction of the kit price.
- Shutoff valve already in place, 3/4-inch line: the EasyFlex EFG-TP-034 is the same role, sized for the more common flagship-unit pipe diameter.
- Not sure which pipe size your install needs: check our gas-line sizing guide — BTU load and run length determine the diameter, and the trap has to match it.
- Electric tankless unit: skip this category entirely — there’s no gas line, so no sediment trap applies.
The bottom line
A gas sediment trap is a $10-$95 fitting that both the IFGC and NFPA 54 require on nearly every gas tankless install, yet it’s one of the first things a DIY installation skips because it looks like an optional extra rather than a code-mandated part. If you’re starting a new gas connection with no shutoff valve yet, the Webstone H-22443-24-FP bundles the full-port valve, trap tee, and flex line into one purchase. If the valve’s already there and you just need the trap itself, the LDR Industries 6092500 (1/2”) or EasyFlex EFG-TP-034 (3/4”) covers the code requirement for about the cost of a fast-food meal. Not sure which pipe diameter your install needs in the first place? Start with our gas-line sizing guide.