ABS DWV Fittings Explained: Complete Guide

Pipe gets all the attention, but abs dwv fittings are what make a drain system actually work. Every turn, branch, and connection in your home's drain-waste-vent plumbing happens through a fitting — and using the wrong one is one of the most common reasons DIY drain work fails inspection. This guide explains every major ABS DWV fitting, what it does, where it belongs, and what it costs.

What Are DWV Fittings?

DWV stands for drain, waste, and vent — the gravity-fed system that carries wastewater out of your home and vents sewer gases through the roof. ABS DWV fittings are the black plastic connectors, elbows, and junctions molded to ASTM D2661 standards that join ABS pipe into a working system. If you are new to the material itself, start with our complete guide to ABS pipe before diving into fittings.

Every legitimate ABS fitting carries printed markings: the manufacturer's name or mark, the nominal size, the material designation (ABS), the ASTM standard, and often a certification mark such as NSF-dwv. If a fitting has no markings, do not use it in a permitted installation — inspectors will flag it. Our pipe identification guide explains how to read these markings in detail.

Fittings come in two connection styles. Hub (socket) fittings have a belled end that slips over the pipe — this is the standard for solvent welding. Spigot (street) fittings have a plain end the same diameter as pipe, designed to fit directly into another fitting's hub, saving space in tight assemblies. You will see the word "street" on these (for example, a "street 90").

Sizes follow the pipe: 1-1/2 inch, 2 inch, 3 inch, and 4 inch cover nearly all residential work. For the full dimension tables, see our ABS pipe sizes chart.

Elbows: 90s, 45s and Street Fittings

Elbows change the direction of a drain line. In DWV work, the type of elbow matters as much as the angle, because drain fittings are designed to keep wastewater flowing smoothly without creating places for solids to collect.

• 90-degree elbow (quarter bend): turns the line 90 degrees. In drain lines, long-sweep 90s are preferred wherever space allows — the gentler curve maintains flow and is easier to snake later. Short-turn (tight) 90s are restricted by code in horizontal drain lines but allowed in venting.
• 45-degree elbow (eighth bend): turns the line 45 degrees. These are the workhorses of drain offsets — two 45s make a smoother, more snakeable offset than a single 90.
• 22-1/2 degree elbow (sixteenth bend): for fine adjustments in alignment, common in shower and tub drains.
• Street elbows: one hub end and one spigot end, letting you glue directly into another fitting's hub. Useful when space is tight, such as inside a wall cavity.
• Long-sweep 90: an extra-gentle 90 required by most codes for horizontal-to-horizontal and some horizontal-to-vertical transitions in drain lines.

Rule of thumb: in any drain carrying solids (toilets, kitchen sinks), use the gentlest bend the space allows. Tight bends in the wrong place cause clogs and will be flagged by an inspector who knows the code.

Tees: Sanitary vs Straight

Tees connect a branch line into a main run. This is where most fitting mistakes happen, because there are two kinds and they are not interchangeable.

• Sanitary tee: has a curved, swept inlet that directs branch flow smoothly into the run. Required by code anywhere a drain branch joins — sinks, tubs, showers, toilets. The sweep keeps solids moving and prevents the branch from fighting the main flow.
• Straight tee (vent tee): has a sharp 90-degree inlet with no sweep. Allowed only in vent piping, where no water flows. Using a straight tee in a drain line is one of the most common DIY code violations.

Orientation matters too: a sanitary tee must be installed so the sweep points in the direction of flow. Installed backwards or on its back (horizontal with the branch pointing up in a drain application), it violates code in most jurisdictions. When in doubt, remember: the curve follows the water.

Wyes and Combination Fittings

Where a branch needs to join a line at a gentler angle than a tee allows, you use a wye.

• Wye (Y): joins a branch at 45 degrees. The standard fitting for connecting branch drains into horizontal main lines — toilets, in particular, almost always connect through a wye or combination fitting.
• Combination wye and 1/8 bend (combo): a wye with a 45 already attached, making a long-sweep 90 turn. The go-to fitting for horizontal-to-horizontal drain connections and for toilet flanges connecting into the main.
• Double wye: connects two branches from opposite sides into one line — common for back-to-back bathroom sinks or tubs.
• Double fixture fitting: similar to a double wye but shaped for two fixtures discharging at once without cross-flow interference.

If you take one principle from this guide, make it this: horizontal drain connections want wyes, not tees. A sanitary tee lying on its side to accept a horizontal branch is a code violation under both major US model codes.

Couplings and Adapters

Couplings join pipe to pipe. Adapters join ABS to something else — another material, a fixture, or a threaded connection.

• Coupling: a straight sleeve joining two lengths of pipe. The simplest fitting in the catalog.
• Repair coupling (slip coupling): has no internal stop, so it can slide fully onto one pipe, then slide back to bridge a gap. Essential for repairs where you cannot flex the existing pipe apart.
• Female adapter: hub on one end, female pipe threads on the other — connects ABS to a threaded male fitting.
• Male adapter: hub on one end, male pipe threads on the other.
• Trap adapter: connects a tubular P-trap (the chrome or plastic trap under your sink) to the ABS drain stub-out in the wall. One of the most commonly purchased DWV fittings in existence.
• Closet flange: the fitting a toilet bolts to, connecting the toilet to a 3- or 4-inch drain. Available in hub and spigot styles, with or without stainless steel rings.
• No-hub coupling (shielded coupling): technically a separate product — a rubber sleeve with a stainless steel shield and clamps. Used to join ABS to cast iron or PVC, or for repairs. See our transition fitting guide for the full story on joining ABS to other materials.

Reducers, Caps and Cleanouts

• Reducer bushing / increaser: changes pipe size within a run — for example, 3-inch to 2-inch. Bushings fit inside a hub; couplings-style reducers have hubs on both ends.
• Cap: permanently seals the end of a pipe — used on rough-in stubs awaiting future fixtures.
• Plug: like a cap but threaded or designed for test and access purposes.
• Cleanout adapter and plug: provides a code-required access point for snaking the line. Cleanouts are required at specific intervals and direction changes — your inspector will check that they exist and are accessible, not buried behind drywall.
• P-trap: the U-shaped fitting holding a water seal that blocks sewer gases. ABS P-traps are solvent-welded; under sinks you will more often see tubular slip-joint traps connecting through a trap adapter.

How Much Do ABS Fittings Cost?

The good news: individual ABS DWV fittings are inexpensive. The bad news for budgeters: a whole-house drain system needs dozens of them, and the total adds up. Typical US retail prices in 2026:

For a typical bathroom rough-in, expect $60–$120 in fittings alone. A whole-house DWV system in new construction commonly runs $400–$900 in ABS fittings before pipe and cement. Buy 10–15% more than your takeoff — a forgotten wye discovered mid-glue-up costs more in lost time than the fitting ever will.

Joining and Code Basics

ABS fittings join to pipe with solvent cement — a chemical weld, not glue. The one-step ABS cement softens both surfaces so they fuse into a single piece. No primer is required for ABS (unlike PVC), which is one reason pros like working with it. Our step-by-step gluing guide walks through the technique, cure times, and the mistakes that cause joint failures.

Three code principles cover most fitting questions:

• Right fitting, right place: sanitary tees for vertical drain takeoffs, wyes and combos for horizontal connections, long sweeps where the code demands them.
• Maintain grade: horizontal drain pipe needs 1/4 inch of fall per foot (for pipe 2-1/2 inches and under). Fittings do not fix bad pitch.
• Keep it accessible: cleanouts at required locations, and no burying mechanical joints where they cannot be reached.

Mixing ABS fittings with PVC pipe (or vice versa) requires the correct transition method — not just the right cement. Our mixing guide explains what the code actually allows.

Planning a drain project and not sure which fittings your takeoff needs? Call (877) 762-1902 — Emergency Plumbing Services helps homeowners scope drain work in 11,114 cities nationwide, and a five-minute conversation can save you a failed inspection.