Fishy smell from dishwasher

A couple of months ago we noticed a "fishy" smell from our 16-year old dishwasher. There is no smell from the drain in the sink next to the dishwasher, from the garbage disposal, from the aerator on the top of the sink or from any other sinks in the house. We tried a number of products including Dishwasher Magic, vinegar in a cup while running the dishwasher and baking soda, none of which got rid of the smell. We called a dishwasher repair person who was unable to diagnose the problem. Since the dishwasher was old, we decided to buy a new dishwasher. We had the old dishwasher removed and there was no smell. When the new dishwasher was installed, we replaced the plastic hose running to the drain of the sink. After running the new dishwasher one time, the new dishwasher gave off the fishy smell. We removed the trap from beneath the sink and there was no fishy smell in the trap. Our municipal water department sent a representative who couldn’t diagnose the problem. We called our plumber twice but he seemed hesitant to schedule a repair, stating that "smells are really hard to figure out." Help!

Hello, Your Plumber is correct. Trying to figure out the smells are tricky but here is one VERY important thing. The drain hose that comes off the bottom of your dshwasher, it should go under and through the cabinet leading to the drain at you sink area. THE IMPORTANT thing is, make sure the drain hose itself has a loop in it at some area (creating a water trap in the hose), this will trap water inside which should eliminate any odor coming back from waste line(sink area). Dont worry, the force of the water pushing from the dishwasher pushing water through then at final washing and draining it will leave that little bit of water in the hose to block all odors from coming back. Then if you have the smell it can only be coming from INSIDE the dishwasher. Hope you understand this. Good Luck

Hello again, WOW you really got me thinking. First I want to say..hello WI neighbor. This is a typical "process elimination" thing. This may be a dumb questions but does you or you husband/partner happen to ice fish this time of year and do you clean any of the gear in your dishwasher? It's a thought because fish oil when intensified with HOT water tends to inbed itself in things. NEXT, do you have well water or city water. Well water with its different minerals smell. NEXT, do you smell the fishy smell out of other hot faucets? If so how old is your water heater? The "anode" rod may be gone. this is a rod inside the water heater that attracts minerals in the water so that it eats away at the rod instead of the steel water heater tank. This odor we plumbers typically call a "rotten egg" odor. Its because the minerals in the water heater are now being intensified by the hot water giving off a stronger odor. These are a few things to check out and think about. Here is something to try. Pour a cup of bleach into your dishwasher with nothing else inside. Let it run a full cycle and see how it smells after.

The installer neglected to put a loop in the plastic drain tube. I have added one. Does it make any difference whether the body of the loop runs over or under where the tube crosses itself? That is, whether or not the loop is suspended below the crossover point? I can do it either way.

We drained the water heater a couple weeks ago to ensure water quality. I looked for an access point for an anode, but I cannot find one. It is a RUUD Tri-point residential gas heater, but there is no access point for an anode on the top of the heater, even though it is clearly shown on the documentation. We have lived here 11 years, so it's probably time to change it, but I can't change it if I can't find it. Weird!

Finally, No one fishes here, but we do cook salmon occasionally (although not since the smell started), but we usually rinse the dishes pretty well before putting them in the dishwasher. Marian takes a fish oil supplement mixed with juice to make the taste tolerable, and then puts the glass in the dishwasher. The glass doesn't smell when it goes in, however. Perhaps it starts to smell when it is heated?!?.

Finally, we have city water that is treated and the source is analyzed every day by the city. There is no smell from any spigot in the house.


Thanks, Greg. (Eric, Mar's husband)

Hello, The plastic or rubber hose should enter into the cabinet below your sink then loop it up as far as you can under the sink then back down to where it connects. You may need to fasten the hose with a hose clamp to the side of the cabinet to keep it in place. That should be fine. Even though water sits inside the dishwasher to block sewer gases this is better way of eliminating the gases going back to the dishwasher. Strange thing is I cant imagine other than the water from your water heater being the smelly issue. If the anode rod is eaten away this will start the smell, usually smells like rotten eggs but you should smell it even if you take a shower. As far as the anode rod, it is usually at the top of the heater and maybe covered by a plastic cap/plug. All heaters are different so its hard to say. But usually you can remove the cap/plug and use a socket to remove the anode rod. Take a peek and see. Once you remove the anode rod you will know if its good or not. Depending on the size heater it is almost the same length as the heater. If it is eaten up, you will visually see it. Sorry, wish I could help more but try it out. Good Luck.

Greg, Thank you so much for helping. We suspect that Marian's daily fish supplement might be the cause becauee she started doing it about the same time as teh problem started. I have a nice loop in the drain tube and we will try using throw away cups fro the daily fish supplement. Perhaps after a few cycles without the fish oil supplement the smell will go away. Perhaps the fish oul supplement only starts to smell when you heat it. I hope this is the case.

there are four caps at the top of the heater bifht next to the perimeter and on the top. I'll try prying one of them off and see what I can see.

THANKS AGAIN> You've been incredibly helpful.

Eric and Marian

Eric and Marian , Yes it might be the fish supplement, reason why is I do the same and I have smelt the fish oil in my sink if I dont rinse it out enough and YES the HOT water intensifies it even more. Try blasting out the dishwasher with some bleach, its safe because it is a small amount deluted with much more water. Run it through once and stop the fish oil, see what happens then. With the water heater, besure to shut of water supply first, open all hot water faucets to releive any pressure before removing anything from your heater. Remember H.W.H. are high in pressure and temperature. Please be careful! Good luck!

I forgot to mention, you may have to pry out every one of those plugs to find the correct one. Some of those plugs are for the holes in the outside shell they use to pump in the foam insulation, so if there is foam insulation pumped in from the top in through one of those holes it might be covering the anode rod socket end. You will know when you find it. It should look like a hex head nut. Good luck, be safe!

MarM said:

Greg, Thank you so much for helping. We suspect that Marian's daily fish supplement might be the cause becauee she started doing it about the same time as teh problem started. I have a nice loop in the drain tube and we will try using throw away cups fro the daily fish supplement. Perhaps after a few cycles without the fish oil supplement the smell will go away. Perhaps the fish oul supplement only starts to smell when you heat it. I hope this is the case.

there are four caps at the top of the heater bifht next to the perimeter and on the top. I'll try prying one of them off and see what I can see.

THANKS AGAIN> You've been incredibly helpful.

Eric and Marian

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I have to jump in here, I dont know plumbing but Im a nutrition specialist. Fish oil supps are made from skin and livers of fish, which is where the toxins in fish accumulate the most; the toxins in fish these days can be very high. There is no substitution for eating fatty fish regularly (salmon, herring, sardines). The fish meat or flesh is much lower in toxins but has the benefits of the good oils. Also, most suppliment companies do not test their product for toxins.

If you can't find the anode rod at any of the four points that you were talking about you may want to remove the hot water outlet nipple. I've seen where the water heater manufacturs have installed the anode rod to the bottom of the hot water outlet making it all one piece.

Hi there,
I had the same problem in my last house.It turned out that the dishwasher and the disposal were connected to the same pipe below sink....I run the disposal before running the dishwasher...solved the problem. Hope this helps.