---
product_id: 287871785
title: "4\" Mainline ABS Backwater Valve"
brand: "mainline"
price: "KD 120.93"
currency: KWD
in_stock: true
reviews_count: 11
category: "Mainline"
url: https://www.desertcart.com.kw/products/287871785-4-mainline-abs-backwater-valve
store_origin: KW
region: Kuwait
---

# Clear top for instant inspection 4-inch full-port flow Integral clean-out for easy rodding 4" Mainline ABS Backwater Valve

**Brand:** mainline
**Price:** KD 120.93
**Availability:** ✅ In Stock

## Summary

> 🚨 Protect your home from costly sewer backups with the valve that works as hard as you do!

## Quick Answers

- **What is this?** 4" Mainline ABS Backwater Valve by mainline
- **How much does it cost?** KD 120.93 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.com.kw](https://www.desertcart.com.kw/products/287871785-4-mainline-abs-backwater-valve)

## Best For

- mainline enthusiasts

## Why This Product

- Trusted mainline brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Effortless Maintenance:** Built-in clean-out allows quick rodding without disassembly or damage.
- • **Instant Visual Assurance:** Clear polycarbonate lid lets you verify valve operation and cleanliness at a glance.
- • **DIY-Friendly Installation:** Fits standard 4" ABS pipes with solvent-weld hubs; install in under an hour with basic tools.
- • **Unmatched Flow Efficiency:** 4" full-port design ensures zero drainage restriction for seamless sewer flow.
- • **Disaster-Proof Your Basement:** Patented valve design slams shut instantly to block sewer backflow during storms.

## Overview

The Mainline 4" ABS Backwater Valve features a patented full-port design with a clear inspection lid and integral clean-out, providing reliable sewer backflow prevention and easy maintenance. Engineered for durability and quick DIY installation, it safeguards basements from flooding and costly damage during extreme weather events.

## Description

The Mainline #4963 Full-Port Backwater Valve is typically installed in homes or buildings that have basements, cellars, crawl spaces or area that are accessible for servicing. The normally open gate allows the sewer system to ‘vent’ any gases that may be causes by positive or negative pressures in the sewer line. The 4963 has a ‘Clear View’ top that makes inspection of the valve quick and simple for the building owner or plumber! As well, the 4963 comes with an integral clean-out for rodding the sewer lateral. Should rodding from the stack be necessary, the snake can easily pass over the open gate and be retracted with out doing any harm to the components.

Review: Saved my basement from a $15,000 disaster – 4" ABS Backwater Valve (the clear lid version) - I wish I never had to learn how important a backwater valve is, but after raw sewage backed up through the basement floor drain during a massive rainstorm two years ago (yes, the city main overflowed), I swore it would never happen again. Spent days cleaning up that nightmare. Never again. Installation Fits perfectly inline on 4" Schedule 40 ABS DWV pipe Solvent-weld hubs on both ends, just like any other ABS fitting Took me about 45 minutes with a saw, primer, and cement (I’m just a homeowner with basic plumbing skills) The clear polycarbonate lid is genius, you can actually see the flapper working and confirm it’s clean/no debris Performance Last month we had another 100-year storm event (over 6" of rain in 4 hours). City sewer was completely overwhelmed again. This valve slammed shut instantly when the pressure reversed. ZERO sewage came up the floor drain. Basement stayed bone dry while my neighbor (who didn’t have one) lost everything again. Flapper still opens freely for normal drainage, no restriction at all when flowing the correct direction. Build quality Heavy-duty ABS body, beefy rubber flapper seal Comes with a neoprene sleeve for the extension rod if you ever need to service it from above Rated for full burial, I have mine 18" underground under the concrete, zero issues Only minor nitpick It’s directional! Make sure the arrow points away from the house (away from your fixtures). I almost glued it backwards because I was rushing. Double-check before you cement. If you tie into a combined sewer or have ever had even a hint of backup, spend the $120 and 2 hours to install this thing. It’s the cheapest insurance policy you’ll ever buy. 100% worth it. Would buy again in a heartbeat. Thank you for saving my sanity (and my finished basement).
Review: Great product. Worth the money - Easy to install. Absolutely works. Had flash flooding and no worries with. y basement getting back flow from city sewer line coming into the house. Very easy access.

## Features

- Mainline Fullport Backwater Valve - 4" Normally Open - ABS
- Unique Patented Design Nearly Eliminates Failure and Allows for Easy Cleaning and Rodding
- Clear top allows for easy inspection

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B07J2QSWX4 |
| Best Sellers Rank | #190,869 in Industrial & Scientific ( See Top 100 in Industrial & Scientific ) #6,370 in Pipe Fittings |
| Brand | Mainline |
| Brand Name | Mainline |
| Customer Reviews | 4.3 out of 5 stars 41 Reviews |
| Exterior Finish | Abs |
| Inlet Connection Size | 14 Inches |
| Inlet Connection Type | Full port |
| Item Dimensions | 18 x 14 x 14 inches |
| Item Weight | 5.97 Pounds |
| Item dimensions L x W x H | 18 x 14 x 14 inches |
| Manufacturer | Mainline Backflow Products Inc. |
| Manufacturer Part Number | 4963 |
| Material | Acrylonitrile Butadiene Styrene |
| Material Type | Acrylonitrile Butadiene Styrene |
| Model Number | ML-4963A |
| Number of Pieces | 1 |
| Number of Ports | 2 |
| Outlet Connection Size | 4 Inches |
| Size | 4" DWV |
| UPC | 696794000014 |
| Unit Count | 1.0 Count |
| Valve Type | Check Valve |

## Product Details

- **Brand:** Mainline
- **Exterior Finish:** Abs
- **Inlet Connection Size:** 14 Inches
- **Inlet Connection Type:** Full port
- **Item dimensions L x W x H:** 18 x 14 x 14 inches
- **Manufacturer:** Mainline Backflow Products Inc.
- **Material:** Acrylonitrile Butadiene Styrene
- **Number of Ports:** 2
- **Outlet Connection Size:** 4 Inches
- **UPC:** 696794000014

## Images

![4" Mainline ABS Backwater Valve - Image 1](https://m.media-amazon.com/images/I/71mnyGvfR8L.jpg)
![4" Mainline ABS Backwater Valve - Image 2](https://m.media-amazon.com/images/I/51X8sADEhXL.jpg)
![4" Mainline ABS Backwater Valve - Image 3](https://m.media-amazon.com/images/I/3146EWdbatL.jpg)
![4" Mainline ABS Backwater Valve - Image 4](https://m.media-amazon.com/images/I/41aUZHTwDyL.jpg)
![4" Mainline ABS Backwater Valve - Image 5](https://m.media-amazon.com/images/I/31RrPX+UmXL.jpg)

## Questions & Answers

**Q: if installed outside, does it need additional cleanouts before/after it or it can be snaked/unclogged thru the lid without any damage to the valve?**
A: My install was interior but buttoned in a concrete floor so I would say you don’t need to do additional clean outs.

## Customer Reviews

### ⭐⭐⭐⭐⭐ Saved my basement from a $15,000 disaster – 4" ABS Backwater Valve (the clear lid version)
*by D***S on December 12, 2025*

I wish I never had to learn how important a backwater valve is, but after raw sewage backed up through the basement floor drain during a massive rainstorm two years ago (yes, the city main overflowed), I swore it would never happen again. Spent days cleaning up that nightmare. Never again. Installation Fits perfectly inline on 4" Schedule 40 ABS DWV pipe Solvent-weld hubs on both ends, just like any other ABS fitting Took me about 45 minutes with a saw, primer, and cement (I’m just a homeowner with basic plumbing skills) The clear polycarbonate lid is genius, you can actually see the flapper working and confirm it’s clean/no debris Performance Last month we had another 100-year storm event (over 6" of rain in 4 hours). City sewer was completely overwhelmed again. This valve slammed shut instantly when the pressure reversed. ZERO sewage came up the floor drain. Basement stayed bone dry while my neighbor (who didn’t have one) lost everything again. Flapper still opens freely for normal drainage, no restriction at all when flowing the correct direction. Build quality Heavy-duty ABS body, beefy rubber flapper seal Comes with a neoprene sleeve for the extension rod if you ever need to service it from above Rated for full burial, I have mine 18" underground under the concrete, zero issues Only minor nitpick It’s directional! Make sure the arrow points away from the house (away from your fixtures). I almost glued it backwards because I was rushing. Double-check before you cement. If you tie into a combined sewer or have ever had even a hint of backup, spend the $120 and 2 hours to install this thing. It’s the cheapest insurance policy you’ll ever buy. 100% worth it. Would buy again in a heartbeat. Thank you for saving my sanity (and my finished basement).

### ⭐⭐⭐⭐⭐ Great product. Worth the money
*by J***N on March 8, 2025*

Easy to install. Absolutely works. Had flash flooding and no worries with. y basement getting back flow from city sewer line coming into the house. Very easy access.

### ⭐ Flapper Valve found not snapped into fitting
*by C***A on September 13, 2025*

Also to address another review that said his valve would not close. that was true with mine as well, but I found out that the flapper valve was not snapped in to the fitting to allow it to rotate and close, once I snapped it in, It was operational. The seller should pay attention to quality control, make sure everything is operational before shipping.

## Frequently Bought Together

- 4" Mainline ABS Backwater Valve
- NDS 113BC* 10 in. Round Valve Box and Cover, 10 in. Height, Irrigation Control Valve Lettering, Black Box, Green Overlapping Cover, Black/Green

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*Product available on Desertcart Kuwait*
*Store origin: KW*
*Last updated: 2026-05-30*