Monday, June 5, 2023


Ask Dave: Why does the RV’s fresh water smell even with a filter?

Dear Dave,
Why does my RV’s fresh water smell even if I use a filter? —Tom, 2019 Coachmen Chaparral 2019

Dear Tom,
There are several things that can cause odors in your fresh water system, starting with the quality of water. Keep in mind that most RVers fill their fresh water tank with hard water from a campground source. Even if you fill your tanks at home, you typically use an outside faucet or one in the garage that is not connected to the water softener, so it will also be hard water. That is the case even though the water at home generally comes from the municipal water system and has been treated somewhat more than a campground that typically just has well water.

Groundwater filters through topsoil, rocks, and other organic material on its way to the aquifer which is the source of water for a well. This water can pick up small traces of bacteria, hydrogen sulfate and other minerals. Letting water stand for several days can cause the smells you are experiencing even though you are using a filter. Most filters simply reduce the calcium, lime, and rust to help prevent clogging in the lines and faucets. Unless you have a heavy-duty filtering system like Clearsource, your water will still have some traces of bacteria and chemicals sitting in the tank.

Sanitize the fresh water system twice a year

Typically, if you drain and flush the system when not RVing, it should reduce the smell. However, keep in mind you can get additional odor from the plastic holding tank, plastic water lines, and water heater, especially in extreme temperatures. I recommend sanitizing the fresh water tank, water heater, and lines twice a year: once when putting it away for storage in the winter, then again midway through the RVing season.

I use a bleach solution of 1/2 cup bleach mixed into a gallon jug of water and pour it through the gravity fill into the fresh water tank. Then I add water to the tank until it’s half full with water from my home outside faucet, as I know it has been treated by my local water department. Run the water through all the faucets, shower heads, and toilet to sanitize everything. If you don’t like the smell of bleach, Thetford makes a fresh water tank cleaner.

One other thing to consider is to identify that the smell is coming from the faucet and not the drain underneath. There could be some nasty “gunk” collecting there from food, grease, and soaps and should also be sanitized.

Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

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Dave Solberg
Dave Solberg
Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. He has been in the RV Industry since 1983 and conducts over 15 seminars at RV shows throughout the country.


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Bob P
11 days ago

Many areas in FL have water from a city source that smells of sulfur, we always bought our water usually from Walmart from their in store water machine in plastic gallon jugs. It was a usually less than $.30 a gallon and used city water for cooking washing dishes and bathing. Local residents didn’t seem to notice the taste but we could. Lol

Thomas D
11 months ago

You can make an excellent taste and odor filter that uses replacement filters. Go to a big box store and ask. Quickly looking online Home Depot has a whole house filter for $45 and the next filters are around $10 for 2. You’d need some fittings that they will be able to sell you. I did that. Keeps the stinky smell and taste out.

Bob P
11 days ago
Reply to  Thomas D

I’ve tried several whole house filters that never removed taste, which brand and type filter do you use?

11 months ago

There are an awful lot of generalizations in this report. Not all well water is hard. Most locales require that water at the campground hose bib represented as potable – not labeled as Non potable -be treated and tested regularly. These can still present as off tastes or smells and be within safe usage ranges. I would look to other sources for any serious smells.

Phil Strong
11 months ago

In response to Dave Telenko. I overcome lack of gravity feed by using Thetford Water freshener. Pour the prescribed quantity for your size tank into your fresh water hose before connecting to rv. Open your tank fill and turn on your water feed. Has worked for me for several years.

11 months ago

Wondering how to put the bleach solution in your fresh water tank as we don’t have a gravity fill, only a hose fitting for filling the tank? I’ve thought about adding one, but have not done it yet!

Thomas D
11 months ago

Empty the hose, pour bleach into hose. Connect hose to supply,keeping it higher so bleach doesn’t run out. Connect camper. Open faucet and bleach goes into tank. Simple😊😊

Bob P
11 days ago
Reply to  Thomas D

I always removed the filter element a pour the proper amount of bleach into the filter housing, reassemble without element turn on water to the tank. After a minute reassemble the element and finish filling the tank.

11 months ago

The amount of bleach used depends on the size of the fresh water tank. 1/4 cup of bleach for each 10-15 gallons. Fill the tank completely to kill anything clinging to the side of the tank. Run the water in all faucets and the toilet. Let it sit at last 12 hours. Drain the water heater and then drain and flush the entire system again with clear water.

Bob p
11 months ago

All the places in FL we have stayed except where we live now has a sulfur smell in the water. Asking the local people who live there they don’t understand what you mean, they’ve been drinking it all their life and don’t notice it. Where we’re at in central FL the water tastes good and doesn’t have a smell, but we’ve got minute particles that look like rust that will clog a filter in a month. I use a RV inline filter as a pre filter for the main house filter which helps but I may be losing line pressure as a result.

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