Find the main water shutoff to the house first. Always do this when you touch supply lines. Don't ask me how I learned this please. Shut the supply line to the dishwasher off.

Remove the brass fitting, wrap each male end in teflon tape,and reassemble. It should be fine.

Ok thanks Joseph!!!

I don't think that connection is where the problem is though. Noting that the hose end connection has no sign of corrosion or leak.

I would check inside the DW to make sure the float isn't stuck and that nothing is blocking the drain for starters.

@ci_lantro The silver waterline connection to the copper pipe has a little bit of green around it, which looks like corrosion. The tray underneath all this had water in it - I'm not sure where else it would come from? It looked to me like the copper connection might not be threaded correctly - like the threads are off from the connection. Does it look correct to you? This is how the installation manual shows that connection:

The tray under these connections had water in it, which is where the float valve is. Is there another float? I removed the tray and emptied it. The right side of the tray was clean but the left side was wet/a bit slimy so I assumed the leak was happening on this side.

I should add that this DW was installed about 2.5 years ago.

I replaced the tray and hooked up the float valve and am running a short cycle per Kitchenaid's troubleshooting guide, looking for leaks. Not sure if something this slow will be immediately apparent but we'll see.

That black tube in front of and to the left of the hose connection is an overflow tube. As seen in this video:

https://www.youtube.com/watch?v=Ub-udPe716o

Note the float switch in the video also. That could be faulty.

@ci_lantro thanks! I will see if that is the culprit. So far I haven't seen anything coming out (ran the express cycle).

Let me see if I understand:

-Float error.

-Water under dishwasher near overflow tube

-You think its a supply line leak because there's a slight amount of corrosion?

Here's an idea instead: The float stuck, usually because there was something on top of (a fork, for example) and it overfilled a bit - and came out the overflow tube.

The float is UNDER the dishwasher, not IN the dishwasher. And it's floating. No forks under the dishwasher. There is a tray under the dishwasher to catch water, and there was water inside the tray, where the float is. I don't know where the water originated because it all migrates towards the float. Hence why I got the error. But that side of the tray, when I pulled it out, was damp, and the other side was dry. Why should I assume it's that tube and not the supply lines, as the tray is under all of it, and it looked to me like the connection wasn't threaded correctly?

I am not a pro, hence why I am here asking the question. No need to be patronizing.

To those of you who answered without making me feel like an idiot first, thank you.

I'll add that this error in the DW manual had you check connections first.

"Why should I assume it's that tube and not the supply lines...?"

The supply line is always pressurized by your household water supply so you would see drips onto the floor when the drip pan was removed. I'd put wrap the supply line joints and end of the overflow tube with toilet paper (very absorbent!), replace the drip pan, and run the dishwasher as normal. Then check the toilet paper. If there's water in the pan but neither piece of toilet paper is wet, the leak is elsewhere.

@wdccruise thanks! I will try that. And thank you for explaining.

You've cleaned and dried the pan. Line it with a piece of newspaper to help with the drip location.

In all of the dishwashers I've seen, the float is in inside the dishwasher linked to a switch. It's a high-water cutoff. It's typically in the left front corner.

And fine - you are new at this... but I don't understand why other people aren't pointing you more in the direction of the float.

@Jake The Wonderdog: "In all of the dishwashers I've seen, the float is in inside the dishwasher..."

The OP didn't disclose his dishwasher model, but float switch part #W11545764 for the KitchenAid KDTM404KPS0 (for example) is in the drip pan. (By putting it there, it would shut off the water regardless of its source, not only if the water level in the tub gets too high. Makes sense. My old Whirlpool dishwasher doesn't have a drip pan and the switch is inside the tub.)

What is your model #?

Not sure what your problem is but my KitchenAid leaked under my island and is in a class action suit for a pump motor diverter shaft seal. Sounds like these are a known problem.

Just FYI

That lawsuit was for dishwashers manufactured between January 1, 2010 and December 31, 2017. The OP's dishwasher is 2-1/2 years old and a problem with prior models does not indicate that there is "a known problem" with his.

I was told by repairman that even after that the problem has not been fixed in newer models.

anj_p,

The brand and model number of the appliance should always both be cited when asking for help with a problem. A manufacturer may have more than one design on the market so citing only the brand isn't sufficient. Some people who participate on GW/Houzz have experience with appliance repair and/or can look up service information.

@dadoes: "The brand and model number of the appliance should always both be cited when asking for help with a problem."

Unfortunately, they almost never do.

I wasn't really asking for help with a problem, I specifically asked about the connection, what the blue stuff was, and whether I needed to get some more if I took the connection apart. I had already read the troubleshooting guidance for my dishwasher but this was not addressed. I figured anyone who had worked with a dishwasher before would know. Joseph answered my question.

Next time if I do need help with a specific issue I will make sure to cite the model number. Didn't think my specific question would need that information as it had more to do with plumbing connections than my specific dishwasher.

There are comments about an overflow float inside the tub (and a bit of resultant snippiness). Your machine apparently is a newer model that has a different method of overflow detection, involving a float under/outside the tub and water seeping through the overflow hose into the tray that is under the machine (which you removed before taking the photo) for the float to sense it there.

The 90° adapter allows for the connection of the water supply line to the machine's water inlet valve. I don't believe there should be any "product" applied to those (blue) threads. The adapter includes a (faucet-type) washer. The supply line also includes a seal for connection to the adapter.

The water supply to the inlet valve is under constant household water supply pressure, as wdccruise explained. The exposed threads appear a bit damaged? There's no leaking visible in your photo at either of the connection points, although possibly a bit of corrosion at the interface of the braided hose connector to the brass adapter?

I stand corrected on the whole float issue - and I apologize for the resultant snippiness.

But I agree that neither of these connections look like it's leaking. You would see water on them right now, and we don't.

The blue nylon solenoid male flitting looks like it had been cross threaded or chewed up with pliers, but doesn't leak. The other connection looks like it may have leaked a little at one time- but not enough to be the source of any problem. Neither one of those connections will benefit from thread sealant because that's not how they seal - which was another issue that was stoking my frustration, because some of the commenters should have known better.

Since we've ruled out the supply line, I'd be looking at two possible scenarios:

1. It overfilled

2. There is a leak other than the supply fittings

I question the corrosion at the top that shouldn't be there. Is water dripping from above on to that? That's right in the area of the water inlet solenoid and I'd check the hose on the outlet of the solenoid.

Jake, I noticed what you point out above. It could be corrosion, or a stray smear of a sealant product the installer applied to the inlet solenoid threads? A bit of something is also on the black overflow tube?

There was enough water collected in the tray to trigger the float.

Excess suds can cause dishwashers to leak. Some pod products can generate suds (recent change in detergent choice?). Spilled rinse aid. Possibly some types of food soils (such as a large amount of egg).

I thank you all for your time. Jake, yes the blue stuff was what I was asking about and wasn't sure what it was. I've cleaned out the tray and run the dishwasher a few times with no additional errors or leaks (I left the toekick and insulation off for a few cycles to make sure there weren't additional leaks). I think this must have been a one off occurrence, probably as you said with the overflow. Not sure why it overflowed... There really is nothing on the inside of the DW to maintain except a foreign object filter). The troubleshooting guide just points you to the connections, and that connection with all the blue stuff on it looked very off, so I assumed that might be where the problem is. (The video linked below shows a clean, metallic threaded piece, which looks very different from mine).

FWIW my DW model is KTDM404KPS0 and the error code was F8E4.

I appreciate everyone's time and help, and even if the initial problem is still unknown, everything seems to be working and it didn't cost me anything but a bit of time to fix. Still would love to know why they used that blue stuff though ...