If you are shopping for a new dishwasher and are interested in how fast a dishwasher drains, you might be surprised to learn this is not really a question that has an easy answer.
How fast does a dishwasher drain? Let’s start with some basics:
The water line that connects your dishwasher to your kitchen plumbing has a maximum flow rate of 1.5 gallons per minute (GPM)
Most home insurance policies only allow you to use appliances that use 2 GPM or less.
Most residential dishwashers are designed to use between 1 and 2 GPM of water.
Commercial dishwashers generally have higher flow rates, but even those often keep the flow rate under 3 GPM.
The default setting on many residential dishwashers is 1.5 GPM
Many modern residential dishwashers have a high loop feature which will increase the water pressure by raising the drain line up above your kitchen sink before it drains out into the sink’s plumbing system. This allows for better drainage but also increases the flow rate, which could be a problem if your home insurance policy does not allow for this setting.
Dishwasher drain times can vary based on a variety of factors, but how long should it take to drain out? How fast does a dishwasher drain?
You probably already know that most dishwasher manufacturers recommend running the garbage disposal before starting the dishwasher. This helps clear any food residue or particles of dirt or debris that may be in the disposal. The reason this is recommended is because if there is a lot of material in the disposal, it can slow down your drain time and make it less effective. It’s a good idea to do this regardless of how fast your dishwasher drains because you want to make sure everything is cleared out properly and not building up inside your appliance.
But what about other things that might affect your dishwasher’s ability to drain? Let’s take a look at some common causes for slow drain times!
One possible cause for slow drainage may be improperly installed pipes. For instance, some new homes have PVC pipes where cast iron was previously used (which can lead to slower drainage speeds). If you notice that water seems to be draining at different rates from various faucets around your house then this could indicate an issue with pipe installation. There may also be blockages due to clogged drains or tree roots growing into the sewer line which
“How fast does a dishwasher drain?” is one of the most common questions we get.
Sure, there are some minimums that are dictated by ANSI Z21.10.1, but what else?
The long and short of it is that dishwashers have to drain in less than 10 minutes, but they can do it a lot faster than that. So how fast?
I put together a video to show you four different dishwasher cycles draining water out of the tub. They range from a very basic wash cycle to an extended rinse cycle. Each test was timed with a stopwatch and repeated three times to make sure it wasn’t a fluke. Here’s what I found:
There’s a lot of misleading and even inaccurate information on the internet about how fast a dishwasher drains. Some of it is just old and out-of-date, but some of it is just plain wrong. We want to set the record straight.
How fast a dishwasher drains depends on three factors:
How high the drain line is, measured from the floor
Whether or not an Air Gap is installed
Whether or not a High Loop is installed
The pump in your dishwasher has to move water up through the drain hose and into either the air gap (if one is installed) or into the disposal below your sink (if one isn’t). If there’s no disposal, then the dishwasher will have to pump water up through the drain hose and over the edge of the sink. The higher you have to pump water, the slower it will drain.
Now that you’re in the know about how long it takes your dishwasher to drain, and how to tell if it’s working properly, check out some of our other dishwasher content:
How To Fix A Dishwasher That Won’t Drain
How To Repair A Dishwasher
How To Clean A Dishwasher
As we’ve discussed before on the blog, many dishwasher models have a high loop installed in their drain lines. The picture above shows a typical installation. If you’re wondering what the purpose of this is, it’s to prevent backflow from a garbage disposal or sink drain into the dishwasher.
When your plumber installs your new dishwasher, he or she will test to make sure that there is no backflow from the sink or disposal by filling the sink with water and running the disposal while someone else watches the dishwasher for any sign of leaks. If there’s any leakage, they’ll install a high loop like this one to prevent it.
But what if you don’t have a garbage disposal? Or if you do but rarely use it? Does having this high loop slow down your washer? Yes! In our testing, we’ve measured dishwashers draining with and without high loops, and they definitely drain slower with them.
A high loop in the drain line won’t necessarily cause any problems. But if you notice that your dishwasher is taking an exceptionally long time to drain the wash water out of your dishwasher, check for a high loop under your kitchen sink and call us at Bay Area Services for help getting rid of it!
My dishwasher has been around since the early 2000s and is a nice size. It’s not super huge and bulky, and it fits well on the countertop. However, in that time, we’ve had a few problems with the quality of the product. One thing we noticed immediately when we bought the product was that it seemed to take a long time to drain.
After about three years of use, we started having problems with water leaking from underneath our cabinet. This was caused by water draining from the dishwasher under our sink. We tried to fix this by using a large plastic sheet across the sink drain, but this did not work very well because there was no way to keep it from running out of the sink in front of our kitchen window.
Some people may have found success by using bleach on their dishwasher drains, but for us, this was not an option because bleach would cause damage to our flooring and cabinets. So we turned to other methods for cleaning out the drains underneath our cabinets and getting rid of water leaks around our sink area.