Carver Owners Forum

I installed a new Kuuma 11 gal hot water heater last summer on my 2000 396 Aft cabin. This weekend I returned to the boat and the water from the hot water tank is discolored and smells like rotten eggs. What went wrong and how do I fix it?

Thanks for your suggestions and comments.

If you run the cold water do you have the same smell or just when the hot is on ?

Have you been using the hot water regularly?

Most likely you'll have to flush the hot water tank when you get on board. I think what happens is the anode in the water tank contributes to the issue your having. Heard of some who had to remove the anode in their household hot water tank to get rid of this issue, sometimes water supplies in different areas react to these anodes.

You need to clean and flush you hot water heater.
Take and flush your hot water heater really good by running the shore water supply thru your tank for about 10 minutes by opening all the faucets onto the hot side and letting it flush.
You need to disconnect your hot water heater from your system.
Pour a cup of bleach into the hot water heater thru the intake port of your hot water heater. You can do this by opening the pressure relief valve to allow the bleach to enter.
Let it sit for 1 hour.
Then take a small box of baking soda and mix w/ a gallon of water and pour into the hot water heater.
Let sit for 1 hour.
Reconnect and flush for 10 minutes.
You should be good to go and no more smell.
This happens a lot when you winterize the system and don't get all the water out of the tank or let it sit for several months without any water going thru.

Sounds like stagnant water odor to me. I used to get that frequently, would use bleach in the entire system, and it would go away. Then, return after water sat in the holding tank for a while. Stopped using the onboard water system and only connect to marina water, unless I am going to be cruising for a few days. There are products to freshen the holding tank, but they are just chemicals you don't really want. Good luck! er

Stopped using the onboard water system and only connect to marina water, unless I am going to be cruising for a few days.

As liveaboards we took the opposite approach: we never use the external marina connection but instead use only the onboard holding tanks. This way the water in our holding tanks is getting "turned over" every 4-6 days and stays "fresh". With our approach we have never had any odors with our water system. I will flush the external connection occasionally, but it's like most things in boating - you gotta figure out what works for your style of boating.

I would not use bleach in that manner, that is very harsh on hardware. Use a product designed for that, they're very mild but do an excellent job, and are hardware friendly. Camco makes a liquid product and so does Starbrite. Pour the recommended amount in a tank that has enough water to run it through your hot water tank and the entire water system by opening one faucet at a time. Let it sit for the recommended time (personally I leave it overnight), then fill your tank with fresh water and run it through the system. Filling your tank and rinsing a couple of times should be enough. I do this once a year at Spring commissioning, gets rid of any slime in the lines, antifreeze odour, etc. In my experience, powdered products are more difficult to work with and can cause other problems so I would stay away from that IMO.

A tablespoon of bleach in a full tank of water periodically throughout the season is all you need to keep the system fresh, and that concentration won't harm your hardware or you while using it. If you drink your potable water, additional considerations are in order.

If you drink your potable water, additional considerations are in order.

Excellent point! We use a Berkey water filter for all our drinking/cooking water. I know it's off topic, but thought I'd throw it out there.