Connecting your washing machine’s drain hose to the sink instead of an independent drain or standpipe is definitely possible. However, there are a few considerations around whether this setup will work well or cause problems. In this blog post, we’ll explore the key factors around successfully draining a washing machine into your sink drain.
How a Washing Machine Drain System Works
First, it helps to understand what’s involved in a washing machine’s drain system. Here’s a quick overview:
- Drain Hose: Washing machines have a flexible drain hose that expels water during the spin and drain cycles. This is usually attached to an independent drain pipe or utility sink standpipe.
- Drain Pump: Most modern washing machines have a drain pump that actively pumps water out during the drain cycle. The pump provides the force needed to expel the water properly.
- Drain Capacity: An average load of laundry can use 40-50 gallons of water. That’s a lot of water that needs to be drained out in a short period of time.
So in summary, we have a powerful drain pump actively pushing out 40+ gallons of water through a hose during the drain cycle. That’s an important backdrop to keep in mind as we look at attaching that to a sink drain.
Will My Sink Drain Handle Washing Machine Discharge?
Whether your sink can handle a washing machine drain comes down to two key factors:
1. Drain Pipe Size
Sink drain pipes are often 1.5 inches in diameter or less. Washing machine drain hoses and standpipes are generally a wider 2 inches. That greater width is to handle the large water volume. So connecting a washing machine to a smaller sink drain can overload it and lead to back ups.
2. Drain Capacity
In addition to a smaller pipe size, many sink drains can’t actually take 40-50 gallons of water in a short period. They simply drain slower than what the washing machine needs to expel. You may end up with the sink overflowing or water slowly draining back up the hose.
However, some sinks do have sufficient drainage capacity, especially laundry utility sinks and some farmhouse styles. Much depends on your specific sink set up.
The key is to monitor the drainage and see if the sink can keep up with a whole wash cycle. If you notice pooling water in the sink or the hose draining slowly, then the sink cannot adequately handle washing machine discharge.
Tips to Successfully Drain Into a Sink
If your sink checks the boxes on plumbing size and drainage rate, then connecting the washing machine is possible. Here are some tips:
Use an Air Gap
Install an air gap fitting between the drain hose and sink. This simple fitting prevents potential back flow from the sink into the washing machine, avoiding contamination.
Secure the Drain Hose
Make sure no part of the drain hose loops higher than the base of the washing machine. A self-priming pump can lose its prime and drainage force if there are high loops in the discharge hose.
Watch the Drainage
Monitor the sink drainage with the first few loads. Make sure there is no overflow or back up while running the washing machine. Abort the cycle if needed by turning off the machine.
Consider a Sink Strainer/Cover
To help avoid debris down the drain, you can secure a sink strainer or cover over the drain opening while running wash loads. Just take care to remove it after so draining isn’t obstructed.
Clean Out Hair & Debris
Check any sink catch screens and drain pipes regularly for accumulated debris that could impede drainage over time. Prevent clogs before they happen.
Following these tips will help ensure successfully routing your washing machine to drain into a sink. But again, first make sure your sink’s plumbing can actually handle the discharge volume in order to avoid back up issues.
When Draining Into a Sink is Not Recommended
While draining a washing machine into a sink can work with the right setup, there are some situations where it’s best avoided if possible:
- Tiny bathroom vessel sinks with narrow drain pipes
- Kitchen sinks without garbage disposals (food debris can clog drains)
- Older plumbing that’s prone to clogging issues
- Sewer lines that already struggle with drainage capacity
The added flow from the washing machine could overwhelm these types of vulnerable plumbing configurations. An alternative laundry drain location would be preferred.
Alternatives to Draining Into a Sink
If connecting to a sink isn’t feasible or advisable for your situation, what are your other options for handling washing machine drainage? A few good alternatives include:
Standpipe
A standpipe is essentially an upright pipe near the washing machine dedicated to receiving its drain flow. The standpipe routes the water down and into larger branch drainage pipes below. This takes the load directly off the main waste lines.
Floor Drain
Some laundry rooms have a floor drain system designed to handle high flow from multiple sources like the washing machine, sink, water heater, etc. Discharging into an intended floor drain can work very well.
Gray Water System
For very specialized setups, there are laundry gray water systems that divert drain water to irrigate landscapes and gardens instead of sending down domestic drains. This takes considerable plumbing work but can be an eco-friendly option.
In summary, standpipes, floor drains or gray water systems are often the preferred approach compared to tying into a sink drain. But again, with sufficient plumbing size and drainage rate, discharging a washing machine into a sink can function successfully.
The Bottom Line
While it may be possible to drain your washing machine into a sink instead of an independent pipe or drain, it’s vital to first verify your sink has adequate plumbing size and drainage capacity. When overtaxed, the added laundry discharge can overwhelm sinks and lead to back ups. Carefully test drainage flow on full wash cycles and watch for signs of struggle. An alternative set up is recommended if the sink can’t keep pace. But with robust enough plumbing, directing washing machine outflow into a sink instead of a dedicated pipe can be accomplished with positive results.
References
American Society of Plumbing Engineers. Plumbing Engineering Design Handbook Volume 2: Plumbing Systems. 2018.
International Association of Plumbing and Mechanical Officials. Uniform Plumbing Code. 2021.
International Code Council. International Plumbing Code. 2021.
Ramsey, Dan. “Can I Drain My Washing Machine into a Sink or Bathtub?” The Spruce. 2021. https://www.thespruce.com/drain-washing-machine-into-sink-or-tub-1824848
Rono, Joseph. “How to Drain a Washing Machine into a Sink.” Dengarden. 2021. https://dengarden.com/appliances/washing-machine-into-sink
Venuto, Anthony. “Can You Drain a Washing Machine into a Kitchen Sink?” Best Life. 2022. https://bestlifeonline.com/can-you-drain-a-washing-machine-into-a-kitchen-sink/
Laura has had an enthusiasm for laundry ever since she was a teenager experimenting with wash cycles. She went on study textile science in college before working in product testing.
Soon, Laura found friends and family constantly asking her laundry advice, realizing she had become an unofficial laundry guru. The questions kept coming in, so Laura decided to start sharing laundry tips online to help more people. The enthusiastic response led her start the blog “Laundry How”.
Now in her late thirties, Laura uses Laundry How to tackle all kinds of laundry topics – stains, fabric care, detergents, and more. She provides advice from both her studies and experience testing techniques out firsthand. Laura continues to grow an engaged community of laundry learners, feeling fulfilled empowering people to make laundry an easy, confidence-building ritual rather than a dreaded chore.