Get the RectorSeal Clean Check 97024: listed to ASME A112.14.1, buried outside and serviced from the yard. Inside on a basement drain: Canplas 223284W. Simplest inline valve: Oatey 43904.
Top pick: RectorSeal Clean Check$195.68 at AmazonPrice as of Oct 24, 2026, 5:30 AM EDT · low stock then
All three are 4-inch PVC sewer backwater valves with a flapper that closes when sewage pushes back. All were new and in stock on Amazon on Oct 23, 2026, and each scores 7.0 or higher.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.com at the time of purchase will apply to the purchase of this product.
How the three compare on our spec score
Five checks from each maker’s data sheet, listing or product page, equal weight. Rules and inputs are in the method section.
PlumbingPicks spec score out of 10, from RectorSeal’s data sheet and ICC-ES PMG-1007 listing, Canplas’s bulletin and Oatey’s product page, read Oct 23, 2026. It is not a flow test of our own or a customer rating.
The checks are what you’d want on paper before burying a valve: whether the maker names the backwater valve standard the code asks for, whether the flapper can be replaced, whether dimensions are published, whether there’s a warranty, and how much back-pressure the flapper is rated to hold.
RectorSeal publishes all five. Canplas and Oatey make sound valves but publish less.
Each backwater valve, in detail
What each maker says, where each one installs, and where each lost points.
4 in. PVCUp to 12 ft deep75 psi flapperASME A112.14.1CSA B181.28 lb
Buy it if
You want the valve on the building sewer outside, so you service it from the yard instead of the basement.
Skip it if
You can only reach the drain from inside; a basement inline valve like the Canplas is easier.
The Clean Check is the backwater valve I’d put on a house that’s had a sewer backup, and I’ve used it. RectorSeal says it prevents sewage backups caused by a plugged sewer, excess volume or groundwater flooding.
It installs outside on the building sewer, up to 12 feet below ground, with no manhole. You reach the flapper from ground level through its riser, so you don’t open a valve in the basement.
RectorSeal’s data sheet describes a T-shaped body, a top and bottom collar and a replaceable PVC flapper with a TPV coating. It says the heavy-duty flapper holds up to 75 psi of back-pressure. The 4-inch PVC kit, 97024, weighs 8 pounds.
The paperwork is the reason it scores 10. Its ICC-ES PMG-1007 listing covers the IPC, IRC and UPC and lists ASME A112.14.1 for backwater valves and CSA B181.2 for PVC DWV, the standards IPC 714.2 names.
RectorSeal publishes flapper replacement instructions for the 3- and 4-inch valves and backs its products with a minimum 3-year limited warranty, no registration needed.
RectorSeal makes the same valve in ABS (97004) and in versions with an adapter and plug (97034). Match the body to your sewer pipe.
It didn’t lose a point on our checks. The trade-off is the dig: it goes in the yard, on the sewer line before it reaches the house.
The ICC-ES listing describes it as a valve for horizontal runs of building sewers, with grade access to maintain the seat and replace the valve disc. RectorSeal’s flyer also marks it as approved by the State of Wisconsin.
My call: it’s the best choice for a finished basement, because nobody has to open a sewer valve inside the house to service it.
4 in. PVCDWV hubsNeoprene O-ring lidAcme-thread lidSleeve kit 223304WWhite
Buy it if
You’re putting a valve on a basement branch or building drain and want a sleeve and lid system for under a slab.
Skip it if
You want the code standard named on the paperwork; RectorSeal’s listing names it.
Canplas is a Canadian maker of DWV fittings, and its 4-inch PVC backwater valve is what I’d put on a basement branch line. I’ve used it.
Canplas’s bulletin explains the job: under normal flow the lightweight flapper opens and lets waste out to the sewer, and during a backflow it seals closed so sewage can’t reach the drains inside.
The valve has a built-in drainage slope, socket-by-socket DWV hubs, and a lid sealed with a neoprene O-ring on Acme threads. Canplas says 2-inch DWV pipe can be solvent-welded to the 4-inch lid as an extension handle to reach the plug.
Canplas sells the parts that matter: a 4-inch flapper with O-ring, a 4-inch sleeve kit (223304W) and sleeve lids for 8-inch SDR 35 sewer pipe. The bulletin gives the 4-inch valve’s drawing dimensions too.
Where it lost points: the bulletin doesn’t name a backwater valve standard, a warranty or a back-pressure rating, each scored 7.
Canplas says that if the valve is buried or under concrete, an access sleeve with a lid must go over the opening so the valve can be inspected. That matches IPC 714.3’s access rule.
The Amazon listing is Canplas’s retail number 73009; its model field reads 223284W, the 4-inch white PVC DWV valve in Canplas’s part list.
Its drawing lists the 4-inch model at 7, 6¼ and 6½ inches across its lettered dimensions, so you can check the fit in a trench or a slab cut before you buy. Canplas makes the same valve from 1½ to 6 inches in PVC and ABS.
My call: Canplas recommends valves on branch lines that serve low fixtures, leaving the main open to drain and vent. That’s the smart layout for a basement bathroom.
4 in. PVCSch 40Hub × hubSolvent weldNeoprene cap sealUPC 038753439044
Buy it if
You want a plain inline valve with a hand-tight cap and parts you can find at any supply house.
Skip it if
You want the most paperwork behind it; RectorSeal publishes standards, dimensions and a pressure rating.
Oatey’s 43904 is the plain inline backwater valve you’ll find at most supply houses, and I’ve used it. Oatey says it protects low areas and basements from backflow or waste from street sewers.
Oatey lists an elastomeric seal on a quick-action flapper for a watertight seal, and a threaded access cap with a neoprene seal that tightens or comes off by hand.
The valve fits 4-inch Schedule 40 PVC with hub-by-hub solvent weld connections, and its hub fits DWV pipe and can be adapted to sewer and drain pipe. It accepts access sleeves made of Schedule 40 pipe.
Oatey sells the wear parts on the same product page: a 4-inch PVC flapper with O-ring (43927) and a 4-inch PVC threaded cap (43918). The listing’s UPC, 038753439044, matches Oatey’s 4-inch PVC valve.
Where it lost points: Oatey’s page doesn’t name a backwater valve standard, list dimensions, give a back-pressure rating, or show warranty terms on the product page, each scored 7.
Oatey also makes the same valve in 3-inch and 6-inch PVC and in 3, 4 and 6-inch ABS. Match the body to your pipe; the 43905 is the 4-inch ABS version.
One odd note: Oatey’s family page describes its backwater valves as preventing pumped water from flowing back into a basin. The 43904’s own features describe sewer backflow, which is how I’d use it.
If you bury it, build the access sleeve from Schedule 40 pipe up to the finished floor, as Oatey allows, so the cap stays reachable. That’s what IPC 714.3 asks for: access to the working parts.
My call: buy a spare flapper with it. Flappers are the part that wears, and having one on the shelf turns a service call into a five-minute swap.
The three valves side by side
From the makers’ sheets and pages. Scroll sideways on a phone.
All three are 4-inch PVC sewer backwater valves. Green marks a strength and amber a gap.
Does code say you need a backwater valve?
Answer three questions. It answers from IPC Section 714 and the makers’ install notes.
The one height that decides it is the rim of the next manhole upstream on the public sewer. If your basement floor is below it, sewage that backs up in the street can rise higher than your floor drain. My call: if your neighborhood has flooded basements in heavy rain, ask the city for that manhole’s rim elevation before you plan the valve.
What IPC Section 714 says
The 2021 International Plumbing Code’s backwater valve rules, in plain words.
Section
What it says
714.1 Sewage backflow
Fixtures on a floor below the next upstream public sewer manhole cover need a backwater valve in the building drain or the branch serving them
714.1 Upper floors
Fixtures on floors above that manhole cover shall not discharge through a backwater valve
714.1 Exception
In existing buildings, fixtures above the manhole cover may discharge through one
714.2 Material
Backwater valves comply with ASME A112.14.1, CSA B181.1 or CSA B181.2
714.3 Location
Installed so the working parts can be reached
Why upper floors shouldn’t drain through it: when the valve closes during a backup, anything draining from above has nowhere to go but out of the lowest fixtures. Canplas makes the same point when it recommends valves on branch lines serving low fixtures, leaving the main line open to drain and vent.
Outside, under the slab or exposed: which valve where
The three picks suit different spots.
Location
Valve
Access
Building sewer, outside
RectorSeal Clean Check
Riser to ground level, up to 12 ft deep
Under a basement slab
Canplas 223284W or Oatey 43904
Access sleeve with lid to the floor
Exposed in a crawlspace or basement
Canplas 223284W or Oatey 43904
Lid or cap within reach
Branch to one low bathroom
Canplas 223284W or Oatey 43904
Sleeve or cleanout-style access
An outside valve keeps the mess outside, which is RectorSeal’s point: no opening a sewer valve in a finished basement. An inside valve is easier to retrofit when the basement floor is already open. For finding where your drain runs, see our drain cleanout locations guide.
How to keep a backwater valve working
My call on the routine, using the makers’ access features.
1
Open the access
Unscrew the cap or lid by hand (Oatey and Canplas say it’s hand-tight).
2
Look at the flapper
It should swing freely and seat flat; clear any debris.
3
Check the seal
Wipe the O-ring or seal and the seat.
4
Replace worn parts
Flappers and caps are sold separately by all three makers.
5
Close it tight
Seat the cap or lid fully so it doesn’t leak sewer gas.
My call: check it once a year and after any backup or heavy storm. A valve stuck open does nothing, and a valve stuck shut backs up your own drains. Wear gloves; it’s a sewer line. A sewer camera can show you whether the line beyond it is clear.
Write the date on the cap or lid each time you check it. If you ever sell the house, a backwater valve with a service record is a selling point, and the next owner will know it’s there. If the valve is outside, mark the riser so nobody mows over it or buries it under landscaping; RectorSeal’s whole design depends on reaching it from ground level.
Backwater valve vs backflow preventer
Same word, two different jobs.
Device
Protects
Where
Backwater valve (this page)
Your drains from sewage pushing back in
Sewer or building drain
Backflow preventer (potable)
The drinking water supply from contamination
Water service and fixtures
Sump check valve
The sump pit from pumped water draining back
Sump discharge line
People search for both as “backflow preventer.” If you’re protecting your drinking water, see our backflow preventer guide. If you need a valve on a sump pump line, that’s a check valve on the discharge, not a backwater valve.
3, 4 or 6 inch: which size?
Each maker’s range, from its own part lists.
Maker
PVC sizes
ABS sizes
RectorSeal Clean Check
3, 4 and 6 in.
3 and 4 in.
Canplas
1½, 2, 3, 4 and 6 in.
1½, 2, 3, 4 and 6 in.
Oatey
3, 4 and 6 in.
3, 4 and 6 in.
Match the valve to the pipe it goes on, in size and material. My call: most house building drains and sewers are 4-inch, which is why all three picks here are 4-inch. A branch to one basement bathroom may be 3-inch; a valve on a single floor drain line may be 2-inch. Don’t reduce the pipe to fit a smaller valve.
My call: PVC and ABS don’t solvent-weld to each other with ordinary cement, so a PVC valve goes on PVC pipe and an ABS valve on ABS. Use a transition fitting where the materials change.
Signs your house needs a backwater valve
My call from service calls, not a maker list.
Sign
What it suggests
Sewage came up a basement floor drain in a storm
The city sewer surcharges higher than your floor
Neighbors have had sewer backups
The street sewer backs up in your area
Basement bathroom or laundry below street level
Low fixtures are the first place sewage comes out
Old combined sewer (storm and sanitary together)
Heavy rain can overload it
Your city offers a backwater valve rebate
The city knows backups happen there
A backwater valve stops the city’s sewage from coming in. It doesn’t stop your own drains from backing up if your line is blocked between the house and the valve; that’s a cleaning job. Our sewer jetter guide covers clearing the line.
Backwater valves we checked and left out
These came up on Amazon and in Google’s results.
Valve
What we found
Why it’s out
Sioux Chief 869 ProCheck
Listings show the brand as “Soux Chief”
Can’t confirm the listing is genuine
RectorSeal 97004
4 in. ABS version, 2 left
Same valve; ABS pipe only
Oatey 4 in. ABS (43905)
Not in stock on Amazon
Not available
Unbranded 4 in. PVC valves
Many listings
No maker documents
Floor drain ball valves
Drain-insert devices
Different kind of product
How to choose in four questions
Question
If yes
If no
Is your floor below the upstream manhole cover?
You need one; keep going
Ask your inspector
Can you dig outside on the sewer line?
RectorSeal Clean Check
Keep going
Under a slab, with a sleeve to the floor?
Canplas 223284W
Keep going
Exposed and easy to reach?
Oatey 43904 or Canplas
Canplas 223284W
Questions people ask
What is a sewer backflow preventer?
A backwater valve: a flapper valve on the sewer or building drain that closes when sewage pushes back toward the house.
Are sewer backflow preventers required?
IPC 714.1 requires one for fixtures on a floor below the next upstream public sewer manhole cover.
Can you put a backflow preventer on a sewer line?
Yes; a backwater valve goes on the building sewer or building drain. RectorSeal’s Clean Check installs outside on the building sewer.
What’s the difference between a backwater valve and a backflow preventer?
A backwater valve keeps sewage out; a backflow preventer protects drinking water.
How does a sewer backflow preventer work?
A flapper swings open for normal flow and seals shut when water pushes back, per Canplas’s description.
What standard should a backwater valve meet?
IPC 714.2: ASME A112.14.1, CSA B181.1 or CSA B181.2.
Can upstairs bathrooms drain through a backwater valve?
In new work, IPC 714.1 says fixtures above the manhole cover shall not; existing buildings are an exception.
How deep can a backwater valve be buried?
RectorSeal’s Clean Check extends up to 12 feet below ground.
Do backwater valves need maintenance?
Yes. IPC 714.3 requires access to the working parts. My call: inspect it yearly and after any backup.
What are the potential problems with a sewer backflow preventer?
My call: debris holding the flapper open, a worn seal, or a closed valve backing up your own drains during a long storm.
How much does a sewer backflow preventer cost?
The valve’s price is on the buy button; installation depends on depth, slab and permit. My call: get a quote with the permit included.
Can I install a backwater valve myself?
My call: it’s permit work in most places, often under a slab or in the yard; hire a licensed plumber.
What size backwater valve do I need?
The same size and material as the pipe it goes on; most house building drains and sewers are 4-inch, and a single basement branch may be 3-inch.
Where does the backwater valve go on a house?
On the building sewer outside (like RectorSeal’s Clean Check) or on the building drain or branch inside, with access to the working parts per IPC 714.3.
Does a backwater valve stop my own drain from backing up?
No. It stops sewage from the city line; a blockage in your own line still needs cleaning.
How we picked these
Why trust me
I’m Isaac Daniels, a licensed journeyman plumber in Georgia (license #JP507711), and I’ve used all three picks. Specs come from RectorSeal’s data sheet and ICC-ES listing, Canplas’s bulletin and Oatey’s product page; code rules from the 2021 IPC. All read Oct 23, 2026. Where I add advice of my own, it’s labeled as my call.
How I pick
One kind of product: 4-inch PVC sewer backwater valves from established DWV makers, new and in stock on Amazon, checked through Amazon’s product data the same day.
Each listing was matched to the maker’s part number; Oatey’s by UPC and Canplas’s by model number.
Each card’s spec score comes from the five checks below. All three score 7.0 or higher.
Where the listing and the maker disagree, the maker’s information is used.
The spec score, check by check
Each check scores 0 to 10 and counts one fifth. It’s our score from maker documents, not a customer rating or a test of our own.
Check (weight)
How it’s scored
Standard named (⅕)
10 when the maker names ASME A112.14.1 or CSA B181; 7 when not
Replaceable flapper (⅕)
10 when the maker sells or documents a replacement flapper; 7 when not
Dimensions published (⅕)
10 when the maker publishes dimensions; 7 when not
Warranty published (⅕)
10 when the maker states warranty terms for it; 7 when not
Back-pressure rating (⅕)
10 when the maker publishes one; 7 when not
Total
Average of the checks, to one decimal
Pick
Standard
Flapper
Dims
Warranty
Pressure
Score
RectorSeal Clean Check
10
10
10
10 (3-yr min)
10 (75 psi)
10.0
Canplas 223284W
7
10
10
7
7
8.2
Oatey 43904
7
10
7
7
7
7.6
Sources
RectorSeal, Clean Check 4 in. PVC Extendable Backwater Valve product page, Clean Check product data sheet (R50382-0125) and flyer. Read Oct 23, 2026.
ICC-ES PMG Product Certificate PMG-1007, Clean Check Extendable Backwater Valves (effective November 2025). Read Oct 23, 2026.
Canplas, Backwater Valves bulletin GD-00168-01-19 and backwater valve product page. Read Oct 23, 2026.
Oatey, Backwater Valves product page (4 in. PVC, part 43904). Read Oct 23, 2026.
International Code Council, 2021 International Plumbing Code, Section 714 Backwater Valves. Read Oct 23, 2026.
Brand-written Amazon listing text for B008A3ULE4, B002KKVET4, B000BQSFJ6, B008A3UKTK, B00GG1BD08 and B007UQLTUM, read through Amazon’s product data, Oct 23, 2026.
Google results for “sewer backflow preventer”: seen Oct 23, 2026. Search volumes from Semrush, Oct 23, 2026.
