Service ports are on tankless system.
Water filter company said no issues with softner system.
When needed call the wife for door refinishing she'll help if she can.

What Brand Tankless W/H do you have?

We have had the problem here from time to time. As Western said, change out the anode for the proper one for your water. But that won’t solve the problem. You need to sanitize your water heater and water lines in the house. Shut the water off to the water heater, unscrew the anode plug and remove the anode. Open the lower water heater drain and let out a couple of gallons of water. Pour bleach, using a funnel, into the anode hole (internet will tell you how much, because I forgot how much). Put in the new anode. I should mention that if you are limited in space above the water heater, buy the segmented anode. Turn the water back on to fill the water heater. Run water in the house to all faucets fed by the water heater until you smell bleach. Let the system sit like that for 8 hours or overnight. That will sanitize your system and end the rotten egg smell. Then run the water from all faucets till the bleach smell is gone.

I have had to do that twice to the water heater at our little guest house. I have found, at least for that little house that doesn’t get a lot of visitors, to turn the gas to the water heater to the Pilot setting. Keeping the water hot unnecessarily will cause you to have to sanitize again before too long. If it’s an electric water heater, turn it off if you aren’t using it. If, however, it’s your main house, sanitize the system and it should stay that way if the water is used regularly. I have never had the problem at the barn apartment (electric water heater is off till needed) or at the main house (water heater in constant use). All anodes have been changed out to the proper one. You’ll need a certain size socket for the anode nut, and be advised that those anode plugs sometimes are hard to get unscrewed.

If my directions aren’t clear, look up how to sanitize your water heater on the internet.

Rinnai is brand.

Water heater is tankless. But yes we'll have bleach all the lines.
Thanks

We have a Rinnai as well. Looking through the manual to see if replacing the anode is an option.

There is no salt in your water when using a water softner.
Smell in hot water is an easy fix --------- there is a bar in your water heater, forget what it is called,,,, unscrew it from the top of your water heater and replace it -------- problem solved.

I just read that your water heater is tankless ---------- maybe get a tank one.

Tankless water heater. I went to the internet to see what they had to say. It appears they use vinegar to flush the unit. I suppose the vinegar will kill the bacteria that causes the rotten egg smell. There wasn’t much discussion about the use of bleach for tankless. Maybe bleach isn’t recommended for a tankless unit, even though it’s suggested for the tank type. Well, the objective is to kill the bacteria, so if vinegar will do that, so be it.

I do know that when we sanitized our travel trailer water tank and lines we used bleach, but were instructed to bypass the water heater.

A buddy of mine has a house in the country that had smelly hot water. He fixed it by increasing the water heater's temperature. He put up warning signs near the showers warning folks that the water may be way too hot.

His water heaters have a tank, so this is just FWI - it might help(?)

Before I went to Camp Grady Spruce I heard about the sulfur smell in the water. We took those fizzy things to put in our water. That was in the days before bottled water.

We run sacrificial anodes in all of our heater treaters.

They make a timed device that drops chlorine tablets into the well. It installs at the wellhead. No experience with one but it sounds good.

When I had the Ranchito between Cistren and Muldoon Tx. it had the nastiest water I had every been around . 600 foot deep well, Kinectico Water System, Settling Tanks. Clorine Injection System. Heck my water well building looked like a city set up. Tanks, Hoses and all kinds of goodies to make it halfway liveable.Think we had around 20 grand in the system and needed constant attention.

The well at my old place was like that. I would pour a cup of bleach down the well between the tubing and casing. I then ran a water hose back into the well between the tubing and casing and let it circulate for ten minutes, then pulled the hose out and let it run on the ground for five minutes and called it good. Another way to help is to use an old style pressure tank with no bladder. There is a sniffle valve located between the first two joints of tubing that will drain back a little water every time the pump cycles. That will help keep some deposits from staying in the tank. A softener works fine with a tankless heater, I have been using it for years, and Rinniah is a good brand heater. The salt is only used in the softener system to backflush the resin, and then it gets a fresh water rinse before it cycles back to the house. When you run a pre filter and then a softener, you will find that it will be several years before you need to de scale the water heater. Find a reputable water treating company, get a thorough water sample test, and go from there, you may or may not end up needing a very elaborate system to alleviate the odor.